:root {
  color-scheme: dark;
  --science-bg: #0a0d14;
  --science-bg-overlay: rgba(8, 11, 19, 0.58);
  --science-bg-image: none;
  --science-surface: rgba(17, 23, 34, 0.74);
  --science-elevated: rgba(23, 31, 45, 0.74);
  --science-border: #283345;
  --science-text: #f5f7fb;
  --science-muted: #a9b4c3;
  --science-focus: #f4c95d;
  --science-success: #66d38e;
  --science-warning: #f0b45a;
  --science-danger: #ff7b8b;
  --science-accent: #8aa4ff;
  --science-accent-ink: #09101c;
  --control-radius: 10px;
  --card-radius: 14px;
  --panel-radius: 18px;
}

body[data-science-subject="chemistry"] {
  --science-bg-image: url("/media/subject-chemistry.jpg");
  --science-bg-overlay: rgba(8, 11, 19, 0.78);
  background-image: linear-gradient(var(--science-bg-overlay), var(--science-bg-overlay)), var(--science-bg-image);
  background-color: var(--science-bg);
  background-repeat: no-repeat;
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
}

body[data-science-subject="physics"] {
  --science-bg-image: url("/media/subject-physics.jpg");
  --science-bg-overlay: rgba(8, 11, 19, 0.78);
  background-image: linear-gradient(var(--science-bg-overlay), var(--science-bg-overlay)), var(--science-bg-image);
  background-color: var(--science-bg);
  background-repeat: no-repeat;
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
}

* { box-sizing: border-box; }

html {
  background-image: linear-gradient(var(--science-bg-overlay), var(--science-bg-overlay));
  background-color: var(--science-bg);
  background-repeat: no-repeat;
  background-size: cover;
  background-position: center;
}

body {
  margin: 0;
  min-width: 320px;
  background-image: linear-gradient(var(--science-bg-overlay), var(--science-bg-overlay)), var(--science-bg-image);
  background-color: var(--science-bg);
  color: var(--science-text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.55;
  letter-spacing: 0;
  background-repeat: no-repeat;
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
}

body.dialog-open { overflow: hidden; }
body.study-mode .rs-support-floating,
body.worksheet-selection-mode .rs-support-floating,
body.worksheet-preview-mode .rs-support-floating { display: none !important; }

body.worksheet-preview-mode { overflow: hidden; }
body.worksheet-preview-mode .science-cookie-notice { display: none !important; }

body[data-science-subject] div[role="region"][aria-label="Cookie notice"] > button {
  background: var(--science-accent) !important;
  color: var(--science-accent-ink) !important;
}

body[data-science-subject] .science-cookie-notice {
  position: relative !important;
  inset: auto !important;
  width: 100% !important;
  border-radius: 0 !important;
  box-shadow: none !important;
}

a { color: var(--science-accent); }
button, input, select, textarea { font: inherit; letter-spacing: 0; }
button, select { cursor: pointer; }
button:disabled { cursor: not-allowed; opacity: .55; }

:focus-visible {
  outline: 3px solid var(--science-focus);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  z-index: 10000;
  top: 8px;
  left: 8px;
  padding: 10px 14px;
  border-radius: var(--control-radius);
  background: var(--science-focus);
  color: var(--science-accent-ink);
  transform: translateY(-160%);
}
.skip-link:focus { transform: translateY(0); }

.science-app { min-height: 100vh; display: flex; flex-direction: column; }

.science-command-bar {
  position: sticky;
  z-index: 100;
  top: 0;
  min-height: 58px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  padding: 8px clamp(12px, 3vw, 32px);
  border-bottom: 1px solid var(--science-border);
  background: color-mix(in srgb, var(--science-surface) 72%, transparent);
  backdrop-filter: none;
}

.science-main,
.science-footer,
.filter-rail,
.search-control input,
.field select,
.field input,
.filter-chip,
.quiet-button,
.icon-button,
.secondary-button,
.filter-trigger,
.load-button,
.question-card,
.worksheet-question-checkbox,
.review-item,
.worksheet-organizer {
  backdrop-filter: none;
}

.question-card,
.worksheet-organizer,
.review-item {
  background: color-mix(in srgb, var(--science-surface) 88%, transparent);
}

.question-card:hover,
.filter-chip,
.quiet-button:hover,
.icon-button:hover,
.secondary-button:hover,
.filter-trigger:hover,
.load-button:hover,
.review-item:hover {
  background: color-mix(in srgb, var(--science-elevated) 88%, transparent);
}

.science-home {
  color: var(--science-text);
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
}
.science-home-compact { display: none; }

.subject-mark {
  padding: 4px 8px;
  border-radius: 7px;
  background: var(--science-accent);
  color: var(--science-accent-ink);
  font-size: 13px;
  font-weight: 700;
}

.workspace-nav { display: flex; flex-shrink: 0; align-self: stretch; gap: 4px; }
.workspace-nav a {
  display: flex;
  align-items: center;
  min-height: 44px;
  padding: 0 10px;
  border-bottom: 2px solid transparent;
  color: var(--science-muted);
  font-size: 14px;
  text-decoration: none;
}
.workspace-nav a[aria-current="page"] { border-color: var(--science-accent); color: var(--science-text); }

.session { display: flex; flex-shrink: 0; align-items: center; gap: 10px; margin-left: auto; min-width: 0; }
.session-name { max-width: 22ch; overflow: hidden; color: var(--science-muted); font-size: 13px; text-overflow: ellipsis; white-space: nowrap; }

.quiet-button, .icon-button, .secondary-button, .filter-trigger, .load-button {
  min-height: 44px;
  border: 1px solid var(--science-border);
  border-radius: var(--control-radius);
  background: var(--science-surface);
  color: var(--science-text);
  font-weight: 600;
}
.quiet-button { padding: 8px 12px; white-space: nowrap; }
.icon-button { width: 44px; padding: 0; font-size: 22px; line-height: 1; }
.secondary-button, .filter-trigger, .load-button { padding: 9px 14px; }
.quiet-button:hover, .icon-button:hover, .secondary-button:hover, .filter-trigger:hover, .load-button:hover { background: var(--science-elevated); border-color: var(--science-muted); }

.primary-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 9px 16px;
  border: 1px solid transparent;
  border-radius: var(--control-radius);
  background: var(--science-accent);
  color: var(--science-accent-ink);
  font-weight: 700;
  text-decoration: none;
}
.primary-button:hover { filter: brightness(1.08); }

.science-main {
  width: 100%;
  max-width: 1500px;
  margin: 0 auto;
  padding: clamp(20px, 4vw, 48px) clamp(12px, 3vw, 34px) 64px;
  flex: 1;
}

.page-heading { margin-bottom: 22px; }
.page-heading h1, .detail-title, .state-panel h1, .topic-heading, .review-heading {
  margin: 0;
  font-family: var(--font-sans);
  font-weight: 700;
  letter-spacing: 0;
}
.page-heading h1 { font-size: clamp(26px, 4vw, 32px); }
.page-heading p { max-width: 68ch; margin: 6px 0 0; color: var(--science-muted); }

.search-row { display: flex; align-items: stretch; gap: 10px; margin-bottom: 16px; }
.search-control { position: relative; flex: 1; }
.search-control input {
  width: 100%;
  height: 48px;
  padding: 10px 46px 10px 42px;
  border: 1px solid var(--science-border);
  border-radius: var(--control-radius);
  background: var(--science-surface);
  color: var(--science-text);
}
.search-control input::placeholder { color: #8491a3; }
.search-symbol { position: absolute; left: 14px; top: 11px; color: var(--science-muted); font-size: 20px; pointer-events: none; }
.search-shortcut { position: absolute; right: 10px; top: 9px; padding: 3px 7px; border: 1px solid var(--science-border); border-radius: 6px; color: var(--science-muted); font-size: 12px; }

.active-filters { display: flex; flex-wrap: wrap; gap: 8px; margin: 0 0 16px; }
.filter-chip {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  padding: 5px 9px;
  border: 1px solid var(--science-border);
  border-radius: 999px;
  background: var(--science-elevated);
  color: var(--science-text);
  font-size: 13px;
}
.filter-chip button { width: 28px; height: 28px; margin: -2px -5px -2px 4px; border: 0; background: transparent; color: var(--science-muted); font-size: 18px; }

.bank-layout { display: grid; grid-template-columns: minmax(210px, 250px) minmax(0, 1fr); gap: 24px; align-items: start; }
.filter-rail { position: sticky; top: 78px; padding-right: 20px; border-right: 1px solid var(--science-border); }
.filter-rail h2 { margin: 0 0 14px; font-size: 16px; }
.filter-stack { display: grid; gap: 14px; }
.field { display: grid; gap: 6px; color: var(--science-muted); font-size: 13px; font-weight: 600; }
.field select, .field input {
  width: 100%;
  min-height: 44px;
  padding: 8px 10px;
  border: 1px solid var(--science-border);
  border-radius: var(--control-radius);
  background: var(--science-surface);
  color: var(--science-text);
}
.filter-actions { display: flex; gap: 8px; margin-top: 16px; }

.results-area { min-width: 0; }
.result-toolbar { display: flex; align-items: center; gap: 10px; min-height: 44px; margin-bottom: 10px; }
.result-count { color: var(--science-muted); font-size: 14px; }
.result-time { margin-left: auto; color: var(--science-muted); font-size: 13px; }
.result-list { display: grid; gap: 10px; margin: 0; padding: 0; list-style: none; }
.question-card {
  position: relative;
  display: grid;
  grid-template-columns: 132px minmax(0, 1fr) auto;
  gap: 14px;
  min-height: 150px;
  padding: 18px;
  border: 1px solid var(--science-border);
  border-radius: var(--card-radius);
  background: var(--science-surface);
}
.question-card-thumbnail { display: block; width: 132px; height: 168px; object-fit: cover; object-position: top; border: 1px solid var(--science-border); border-radius: 9px; background: #fff; }
.question-card-thumbnail--missing { display: grid; place-items: center; padding: 8px; background: var(--science-elevated); color: var(--science-muted); font-size: 11px; text-align: center; }
.question-card:hover { border-color: color-mix(in srgb, var(--science-accent) 68%, var(--science-border)); background: var(--science-elevated); }
.question-main { min-width: 0; }
.question-title-row { display: flex; align-items: center; flex-wrap: wrap; gap: 8px; }
.question-id { color: var(--science-accent); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 13px; font-weight: 700; }
.type-badge, .answer-badge {
  display: inline-flex;
  align-items: center;
  min-height: 25px;
  padding: 2px 7px;
  border: 1px solid var(--science-border);
  border-radius: 6px;
  color: var(--science-muted);
  font-size: 12px;
  font-weight: 600;
}
.answer-badge[data-status="verified"] { border-color: color-mix(in srgb, var(--science-success) 60%, var(--science-border)); color: var(--science-success); }
.answer-badge[data-status="source_unavailable"] { color: var(--science-warning); }
.question-excerpt { max-width: 75ch; margin: 11px 0; color: var(--science-text); white-space: pre-line; }
.question-meta, .breadcrumb { display: flex; flex-wrap: wrap; gap: 4px 10px; color: var(--science-muted); font-size: 13px; }
.breadcrumb { margin-bottom: 8px; }
.question-open { align-self: center; color: var(--science-accent); font-weight: 700; text-decoration: none; }
.question-open::after { content: " →"; }
.load-wrap { display: flex; justify-content: center; padding: 22px 0; }

.worksheet-floating-button {
  position: fixed;
  z-index: 420;
  left: max(8px, env(safe-area-inset-left));
  bottom: max(16px, env(safe-area-inset-bottom));
  display: grid;
  width: 44px;
  height: 44px;
  padding: 0;
  place-items: center;
  border: 1px solid color-mix(in srgb, var(--science-accent) 58%, var(--science-border));
  border-radius: 50%;
  background: var(--science-surface);
  color: var(--science-accent);
  box-shadow: 0 8px 26px rgba(0, 0, 0, .3);
}
.worksheet-floating-button:hover { border-color: var(--science-accent); background: var(--science-elevated); }
.worksheet-floating-button::after {
  content: attr(data-tooltip);
  position: absolute;
  left: 0;
  bottom: calc(100% + 9px);
  width: max-content;
  max-width: min(240px, calc(100vw - 32px));
  padding: 6px 9px;
  border: 1px solid var(--science-border);
  border-radius: 7px;
  background: var(--science-elevated);
  color: var(--science-text);
  font-size: 12px;
  font-weight: 600;
  line-height: 1.35;
  opacity: 0;
  pointer-events: none;
  transform: translateY(3px);
  transition: opacity 120ms ease, transform 120ms ease;
}
.worksheet-floating-button:hover::after,
.worksheet-floating-button:focus-visible::after { opacity: 1; transform: translateY(0); }
.worksheet-floating-button[hidden], .worksheet-selection-toolbar[hidden] { display: none; }

.worksheet-selection-toolbar {
  position: fixed;
  z-index: 430;
  left: 50%;
  bottom: max(14px, env(safe-area-inset-bottom));
  display: flex;
  width: max-content;
  max-width: calc(100vw - 150px);
  min-height: 62px;
  padding: 8px 10px 8px 15px;
  align-items: center;
  gap: 16px;
  border: 1px solid color-mix(in srgb, var(--science-accent) 52%, var(--science-border));
  border-radius: 16px;
  background: color-mix(in srgb, var(--science-surface) 88%, transparent);
  box-shadow: 0 10px 28px rgba(0, 0, 0, .30);
  backdrop-filter: blur(8px);
  transform: translateX(-50%);
}
.worksheet-selection-count { flex: 0 0 auto; color: var(--science-text); font-size: 14px; font-weight: 700; white-space: nowrap; }
.worksheet-selection-actions { display: flex; align-items: center; gap: 7px; }
.worksheet-selection-actions button { min-height: 42px; white-space: nowrap; }
body.worksheet-builder-route .science-main,
body.worksheet-builder-route .science-footer { padding-left: max(56px, calc(56px + env(safe-area-inset-left))); }
body.worksheet-selection-mode .science-main { padding-bottom: 150px; }

.worksheet-question-choice {
  position: absolute;
  z-index: 2;
  top: 12px;
  right: 12px;
  display: grid;
  width: 44px;
  height: 44px;
  place-items: center;
  border: 1px solid var(--science-border);
  border-radius: 50%;
  background: var(--science-elevated);
  cursor: pointer;
}
.worksheet-question-checkbox { width: 21px; height: 21px; margin: 0; accent-color: var(--science-accent); cursor: pointer; }
body.worksheet-selection-mode .question-title-row { padding-right: 48px; }
.question-card--selected {
  border-color: var(--science-accent);
  box-shadow: inset 4px 0 0 var(--science-accent);
}
.worksheet-selection-hint { align-self: center; color: var(--science-muted); font-size: 13px; font-weight: 600; }

.worksheet-preview-root {
  position: fixed;
  z-index: 2000;
  inset: 0;
  overflow: auto;
  overscroll-behavior: contain;
  background: rgba(4, 7, 12, .94);
  color: var(--science-text);
}
.worksheet-preview { min-height: 100%; }
.worksheet-preview-chrome {
  position: sticky;
  z-index: 2;
  top: 0;
  width: min(980px, calc(100% - 24px));
  margin: 0 auto;
  padding: 16px 0;
  background: color-mix(in srgb, var(--science-bg) 88%, transparent);
  backdrop-filter: blur(8px);
}
.worksheet-preview-heading { display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.worksheet-preview-heading h2 { margin: 0; font-size: clamp(22px, 3vw, 28px); }
.worksheet-preview-heading p { margin: 2px 0 0; color: var(--science-muted); }
.worksheet-preview-actions { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 8px; }
.worksheet-preview-settings { display: grid; margin-top: 14px; align-items: end; grid-template-columns: minmax(220px, 1fr) auto; gap: 14px; }
.worksheet-metadata-toggle { display: flex; min-height: 44px; align-items: center; gap: 9px; color: var(--science-text); font-size: 14px; font-weight: 600; }
.worksheet-metadata-toggle input { width: 19px; height: 19px; accent-color: var(--science-accent); }
.worksheet-organizer { margin-top: 12px; border: 1px solid var(--science-border); border-radius: var(--control-radius); background: var(--science-surface); }
.worksheet-organizer summary { min-height: 42px; padding: 9px 12px; cursor: pointer; font-weight: 700; }
.worksheet-organizer-list { display: grid; max-height: 230px; gap: 6px; margin: 0; padding: 0 10px 10px; overflow: auto; list-style: none; }
.worksheet-organizer-item { display: flex; min-width: 0; align-items: center; justify-content: space-between; gap: 12px; padding: 7px 8px; border-top: 1px solid var(--science-border); color: var(--science-muted); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 13px; }
.worksheet-organizer-item > span:first-child { overflow-wrap: anywhere; }
.worksheet-organizer-actions { display: flex; flex: 0 0 auto; gap: 5px; }
.worksheet-organizer-actions .icon-button { width: 38px; min-height: 38px; height: 38px; font-size: 18px; }
.worksheet-remove-button { min-height: 38px; padding: 6px 10px; border: 1px solid var(--science-border); border-radius: 8px; background: var(--science-surface); color: var(--science-text); font-weight: 600; }

.worksheet-pages { display: grid; gap: 24px; width: min(210mm, calc(100% - 24px)); margin: 0 auto; padding: 22px 0 48px; }
.worksheet-print-page {
  display: flex;
  min-height: 280mm;
  padding: 14mm 15mm 12mm;
  flex-direction: column;
  break-inside: avoid;
  border-radius: 3px;
  background: #fff;
  color: #111;
  box-shadow: 0 14px 45px rgba(0, 0, 0, .4);
}
.worksheet-page-body { display: flex; min-height: 0; flex: 1; flex-direction: column; }
.worksheet-document-title { margin: 0 0 7mm; color: #111; font-family: Georgia, "Times New Roman", serif; font-size: 24pt; line-height: 1.15; text-align: center; overflow-wrap: anywhere; }
.worksheet-question-heading { margin: 0; color: #111; font-family: var(--font-sans); font-size: 15pt; line-height: 1.25; overflow-wrap: anywhere; }
.worksheet-question-metadata { margin: 2mm 0 0; color: #333; font-size: 10pt; line-height: 1.35; overflow-wrap: anywhere; }
.worksheet-source-metadata { margin: 1mm 0 4mm; color: #555; font-size: 8.5pt; line-height: 1.35; overflow-wrap: anywhere; }
.worksheet-question-figure { display: flex; min-height: 0; margin: 5mm 0 0; flex: 1; flex-direction: column; align-items: center; justify-content: flex-start; }
.worksheet-question-image { display: block; width: 100%; min-height: 0; max-width: 100%; max-height: 235mm; flex: 1; object-fit: contain; object-position: top center; }
.worksheet-question-figure figcaption { margin-top: 2mm; color: #555; font-size: 8.5pt; }
.worksheet-question-text, .worksheet-question-error { margin-top: 8mm; padding: 6mm; border: 1px solid #bbb; color: #111; white-space: pre-wrap; overflow-wrap: anywhere; }
.worksheet-question-error { border-color: #8c3b3b; }
.worksheet-image-error { margin: 8mm 0; padding: 5mm; border: 1px solid #8c3b3b; color: #6d2020; }
.worksheet-page-footer { display: flex; min-height: 8mm; margin-top: 5mm; padding-top: 2.5mm; align-items: flex-start; justify-content: space-between; gap: 8mm; border-top: .25mm solid #aaa; color: #444; font-family: var(--font-sans); font-size: 8pt; line-height: 1.3; }
.worksheet-attribution { min-width: 0; overflow-wrap: anywhere; }
.worksheet-attribution a { color: inherit; text-decoration: underline; text-underline-offset: 1px; }
.worksheet-page-number { flex: 0 0 auto; white-space: nowrap; }
.worksheet-preview-loading, .worksheet-preview-empty { padding: 30px; border: 1px solid var(--science-border); border-radius: var(--card-radius); background: var(--science-surface); color: var(--science-muted); text-align: center; }
.worksheet-preview-empty h3 { margin-top: 0; color: var(--science-text); }

mark { padding: 0 2px; border-radius: 3px; background: var(--science-focus); color: var(--science-accent-ink); }

.state-panel {
  max-width: 720px;
  padding: 26px;
  border: 1px solid var(--science-border);
  border-radius: var(--panel-radius);
  background: var(--science-surface);
}
.state-panel p { color: var(--science-muted); }
.state-actions, .detail-actions, .answer-actions, .buddy-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 18px; }
.error-text { color: var(--science-danger); }
.suggestion { margin: 0 0 14px; padding: 12px 14px; border-left: 3px solid var(--science-focus); background: var(--science-surface); }

.skeleton-list { display: grid; gap: 10px; }
.skeleton {
  height: 154px;
  border: 1px solid var(--science-border);
  border-radius: var(--card-radius);
  background: linear-gradient(90deg, var(--science-surface) 20%, var(--science-elevated) 45%, var(--science-surface) 70%);
  background-size: 250% 100%;
  animation: skeleton 1.3s linear infinite;
}
@keyframes skeleton { to { background-position: -250% 0; } }

.topic-browser { max-width: 1050px; }
.topic-group { padding: 18px 0; border-top: 1px solid var(--science-border); }
.topic-group:first-of-type { border-top: 0; }
.topic-group h2 { margin: 0 0 8px; font-size: 20px; }
.topic-children { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 8px; }
.topic-link { display: flex; justify-content: space-between; gap: 12px; min-height: 48px; padding: 11px 12px; border: 1px solid var(--science-border); border-radius: var(--control-radius); background: var(--science-surface); color: var(--science-text); text-decoration: none; }
.topic-link:hover { border-color: var(--science-accent); }
.topic-count { color: var(--science-muted); font-size: 13px; white-space: nowrap; }

body.study-mode {
  display: flex;
  height: 100vh;
  height: 100dvh;
  min-height: 0;
  flex-direction: column;
  overflow: hidden;
  overflow: clip;
}
body.study-mode .science-cookie-notice { flex: 0 0 auto; }
body.study-mode .science-app { min-height: 0; flex: 1 1 auto; overflow: hidden; overflow: clip; }
body.study-mode .science-command-bar { position: relative; flex: 0 0 auto; }
body.study-mode .science-main {
  max-width: none;
  min-height: 0;
  margin: 0;
  padding: 8px clamp(8px, 1vw, 16px) 10px;
  overflow: hidden;
  overflow: clip;
}
body.study-mode #scienceRoute { width: 100%; height: 100%; min-height: 0; }
body.study-mode .science-footer { display: none; }
.study-shell {
  display: grid;
  width: 100%;
  height: 100%;
  min-height: 0;
  max-width: none;
  margin: 0;
  grid-template-rows: auto minmax(0, 1fr) auto;
}
.back-link { display: inline-block; margin-bottom: 5px; color: var(--science-muted); font-size: 13px; text-decoration: none; }
.detail-header {
  min-width: 0;
  padding: 0 4px 7px;
  border-bottom: 1px solid var(--science-border);
}
.question-meta-row {
  display: flex;
  min-width: 0;
  flex-wrap: wrap;
  align-items: center;
  gap: .28rem .45rem;
  color: var(--science-muted);
  font-size: clamp(.85rem, .35vw + .78rem, 1rem);
  line-height: 1.4;
}
.question-detail-id {
  margin: 0;
  color: var(--science-text);
  font-family: var(--font-sans);
  font-size: 1em;
  font-weight: 650;
  line-height: inherit;
  overflow-wrap: anywhere;
}
.question-meta-separator { color: color-mix(in srgb, var(--science-muted) 68%, transparent); }
.detail-mobile-switcher { display: none; }
.detail-grid {
  --detail-question-width: 50%;
  display: grid;
  min-height: 0;
  grid-template-columns: minmax(0, var(--detail-question-width)) 12px minmax(0, 1fr);
  gap: 0;
  padding-top: 8px;
  align-items: stretch;
  overflow: hidden;
  overflow: clip;
}
.question-pane { height: 100%; min-width: 0; min-height: 0; overflow: hidden; overflow: clip; }
.detail-split-handle {
  position: relative;
  align-self: stretch;
  min-height: 0;
  cursor: col-resize;
  touch-action: none;
  outline: 0;
}
.detail-split-handle::before {
  content: "";
  position: absolute;
  inset: 0 4px;
  border-radius: 999px;
  background: transparent;
  transition: background-color 140ms ease;
}
.detail-split-handle span {
  position: sticky;
  top: 46vh;
  display: block;
  width: 3px;
  height: 54px;
  margin: 28px auto;
  border-radius: 999px;
  background: var(--science-border);
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--science-bg) 75%, transparent);
  transition: width 140ms ease, background-color 140ms ease;
}
.detail-split-handle:hover::before,
.detail-split-handle:focus-visible::before,
.detail-grid[data-resizing="true"] .detail-split-handle::before { background: color-mix(in srgb, var(--science-accent) 11%, transparent); }
.detail-split-handle:hover span,
.detail-split-handle:focus-visible span,
.detail-grid[data-resizing="true"] .detail-split-handle span { width: 4px; background: var(--science-accent); }
body.is-resizing-question-split, body.is-resizing-question-split * { cursor: col-resize !important; user-select: none !important; }
.question-image-viewer {
  display: flex;
  height: 100%;
  min-width: 0;
  min-height: 0;
  flex-direction: column;
  overflow: hidden;
  overflow: clip;
  border: 1px solid var(--science-border);
  border-radius: var(--panel-radius);
  background: color-mix(in srgb, var(--science-surface) 86%, #fff);
  box-shadow: 0 14px 32px rgba(0, 0, 0, .14);
}
.question-viewer-toolbar {
  position: sticky;
  z-index: 3;
  top: 0;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 7px;
  min-height: 52px;
  padding: 8px 10px;
  border-bottom: 1px solid var(--science-border);
  background: color-mix(in srgb, var(--science-elevated) 88%, transparent);
  backdrop-filter: blur(7px);
}
.viewer-tool {
  min-height: 36px;
  padding: 6px 10px;
  border: 1px solid var(--science-border);
  border-radius: 8px;
  background: var(--science-surface);
  color: var(--science-text);
  font-weight: 600;
}
.viewer-tool:hover { border-color: var(--science-accent); }
.viewer-zoom-status { margin-left: auto; color: var(--science-muted); font-size: 12px; }
.question-image-viewport {
  min-height: 0;
  max-height: none;
  flex: 1 1 auto;
  overflow: auto;
  overscroll-behavior: contain;
  touch-action: pinch-zoom pan-x pan-y;
  background: #d7d9dd;
  scrollbar-color: #8b929e #e6e8eb;
  cursor: grab;
}
.question-image-viewport:focus-visible { outline: 3px solid var(--science-focus); outline-offset: -3px; }
.question-image-viewport.is-panning { cursor: grabbing; user-select: none; }
.question-image-pages { width: 100%; min-width: 0; margin-inline: auto; transition: width 120ms ease-out; }
.question-image-page { margin: 0; padding: 16px; }
.question-image-page + .question-image-page { border-top: 2px solid #b8bdc5; }
.question-image-page figcaption { margin: 0 0 8px; color: #3b414b; font-size: 12px; font-weight: 700; }
.question-source-image {
  display: block;
  width: 100%;
  height: auto;
  margin-inline: auto;
  background: #fff;
  box-shadow: 0 5px 18px rgba(0, 0, 0, .2);
  image-rendering: auto;
}
.question-image-unavailable { margin: 18px; padding: 22px; border: 1px solid var(--science-warning); border-radius: var(--control-radius); background: var(--science-surface); color: var(--science-text); }
.source-citation { display: flex; align-items: center; flex-wrap: wrap; gap: 9px 12px; padding: 13px 14px; border-top: 1px solid var(--science-border); color: var(--science-muted); font-size: 12px; }
.source-citation p { flex: 1 1 220px; margin: 0; line-height: 1.45; }
.source-citation-compact { display: none; }
.source-citation .secondary-button, .source-citation .quiet-button { min-height: 38px; }
.question-image-viewer:fullscreen, .question-image-viewer.is-expanded { position: fixed; z-index: 10000; inset: 0; border: 0; border-radius: 0; background: var(--science-bg); }
.question-image-viewer:fullscreen .question-image-viewport, .question-image-viewer.is-expanded .question-image-viewport { max-height: none; }
.answer-workspace {
  display: flex;
  position: relative;
  top: auto;
  height: 100%;
  min-width: 0;
  min-height: 0;
  padding: 0;
  flex-direction: column;
  gap: 0;
  overflow-x: clip;
  overflow-y: auto;
  overscroll-behavior: contain;
  border: 0;
  border-radius: var(--panel-radius);
  background: transparent;
}
.answer-workspace h2 { margin: 0; font-size: 19px; }
.answer-workspace p { color: var(--science-muted); }
.answer-tools {
  position: absolute;
  z-index: 6;
  top: 13px;
  right: 100px;
  max-width: 110px;
  max-height: 42px;
  overflow: hidden;
  border: 1px solid var(--science-border);
  border-radius: 9px;
  background: var(--science-surface);
  box-shadow: 0 5px 18px rgba(0, 0, 0, .24);
}
.answer-tools summary {
  min-height: 40px;
  padding: 8px 11px;
  color: var(--science-text);
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  white-space: nowrap;
}
.answer-tools[open] { inset: 0; max-width: none; max-height: none; overflow: auto; border-radius: 12px; }
.answer-tools[open] summary { position: sticky; z-index: 1; top: 0; background: var(--science-surface); }
.answer-tools-content { padding: 0 14px 14px; }
.answer-input, math-field {
  display: block;
  width: 100%;
  min-height: 110px;
  margin-top: 12px;
  padding: 12px;
  border: 1px solid var(--science-border);
  border-radius: var(--control-radius);
  background: var(--science-bg);
  color: var(--science-text);
  resize: vertical;
}
.choice-list { display: grid; gap: 8px; margin: 14px 0 0; }
.choice-option { display: flex; align-items: center; gap: 10px; min-height: 44px; padding: 8px 10px; border: 1px solid var(--science-border); border-radius: var(--control-radius); }
.feedback { margin-top: 14px; padding: 12px; border-left: 3px solid var(--science-warning); background: var(--science-elevated); }
.feedback[data-status="correct"] { border-color: var(--science-success); }
.feedback[data-status="incorrect"], .feedback[data-status="invalid"] { border-color: var(--science-danger); }
.answer-reveal { margin-top: 14px; padding-top: 14px; border-top: 1px solid var(--science-border); white-space: pre-wrap; }
.source-disclosure { margin-top: 30px; padding-top: 14px; border-top: 1px solid var(--science-border); color: var(--science-muted); font-size: 13px; }
.source-disclosure summary { min-height: 44px; padding: 10px 0; cursor: pointer; }
.study-nav { display: flex; min-height: 38px; justify-content: space-between; gap: 10px; padding-top: 7px; }
.study-nav .secondary-button { min-height: 36px; padding-block: 5px; }

.ai-tutor-panel,
.ai-tutor-panel button,
.ai-tutor-panel textarea {
  font-family: var(--font-sans);
}

.ai-tutor-panel {
  --ai-surface: color-mix(in srgb, var(--science-elevated) 66%, #0e1420);
  --ai-border: color-mix(in srgb, var(--science-border) 72%, var(--science-accent));
  display: flex;
  position: relative;
  min-width: 0;
  min-height: 0;
  margin: 0;
  padding: 16px;
  flex: 1 1 auto;
  flex-direction: column;
  overflow: hidden;
  border: 1px solid var(--ai-border);
  border-radius: 16px;
  background:
    radial-gradient(circle at 92% 0%, color-mix(in srgb, var(--science-accent) 8%, transparent), transparent 48%),
    color-mix(in srgb, var(--science-surface) 92%, #151b29);
  box-shadow: 0 10px 24px rgba(0, 0, 0, .14);
  color: var(--science-text);
  font-size: clamp(17px, .7vw + 12px, 21px);
  line-height: 1.65;
}

.ai-tutor-header { display: flex; flex: 0 0 auto; align-items: center; gap: 10px; padding-bottom: 10px; border-bottom: 1px solid var(--science-border); }
.ai-tutor-header h3 { margin: 0; color: var(--science-text); font-size: clamp(22px, 1.7vw, 28px); font-weight: 700; line-height: 1.15; }
.ai-tutor-mark {
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border: 1px solid color-mix(in srgb, var(--science-accent) 55%, var(--science-border));
  border-radius: 11px;
  background: color-mix(in srgb, var(--science-accent) 13%, var(--science-elevated));
  color: var(--science-accent);
  font-size: 18px;
}
.ai-collapse-button { margin-left: auto; min-height: 38px; padding: 6px 10px; border: 1px solid var(--science-border); border-radius: 8px; background: transparent; color: var(--science-muted); font-size: 13px; font-weight: 600; }
.ai-tutor-panel[data-collapsed="true"] { padding-bottom: 12px; }
.ai-tutor-body { display: flex; position: relative; min-height: 0; flex: 1 1 auto; flex-direction: column; padding-top: 8px; }
.ai-tutor-content { display: flex; min-height: 0; flex: 1 1 auto; flex-direction: column; transition: filter 160ms ease, opacity 160ms ease; }

.rishai-support-interstitial[hidden] { display: none !important; }
.rishai-support-interstitial {
  position: absolute;
  z-index: 8;
  inset: 0;
  display: grid;
  min-height: 0;
  padding: clamp(12px, 3vw, 30px);
  place-items: center;
  overflow: auto;
  background: rgba(5, 9, 17, .34);
}
.ai-tutor-panel[data-support-prompt="open"] .ai-tutor-content { filter: blur(3px); opacity: .38; pointer-events: none; user-select: none; }
.rishai-support-dialog-card { width: min(100%, 560px); padding: clamp(21px, 3vw, 30px); border: 1px solid color-mix(in srgb, var(--science-accent) 54%, var(--science-border)); border-radius: 16px; background: color-mix(in srgb, var(--science-elevated) 96%, #080d16); box-shadow: 0 22px 50px rgba(0, 0, 0, .46); }
.rishai-support-dialog-mark { display: grid; width: 40px; height: 40px; place-items: center; border-radius: 11px; background: color-mix(in srgb, var(--science-accent) 16%, var(--science-surface)); font-size: 23px; line-height: 1; }
.rishai-support-dialog-card h4 { margin: 14px 0 8px; color: var(--science-text); font-size: clamp(21px, 2.6vw, 28px); line-height: 1.2; }
.rishai-support-dialog-card p { margin: 0; color: var(--science-muted); font-size: 15px; line-height: 1.55; }
.rishai-support-actions { display: flex; margin-top: 21px; gap: 10px; }
.rishai-support-primary,
.rishai-support-secondary { min-height: 46px; padding: 10px 16px; border-radius: 10px; font-size: 14px; font-weight: 720; cursor: pointer; }
.rishai-support-primary { border: 1px solid transparent; background: var(--science-accent); color: var(--science-accent-ink); }
.rishai-support-secondary { border: 1px solid var(--science-border); background: transparent; color: var(--science-text); }
.rishai-support-primary:hover { filter: brightness(1.08); }
.rishai-support-secondary:hover { border-color: var(--science-accent); }
.rishai-support-primary:focus-visible,
.rishai-support-secondary:focus-visible { outline: 3px solid #fff; outline-offset: 3px; }

.ai-image-warning {
  margin: 10px 0;
  padding: 9px 10px;
  border-left: 3px solid var(--science-warning);
  border-radius: 7px;
  background: color-mix(in srgb, var(--science-warning) 8%, var(--science-surface));
  color: var(--science-text);
  font-size: 12px;
}

.ai-chat-shell { position: relative; min-height: 0; flex: 1 1 auto; overflow: hidden; }
.ai-chat-thread {
  height: 100%;
  min-height: 0;
  max-height: none;
  padding: 4px 5px 54px;
  overflow-y: auto;
  overscroll-behavior: contain;
  scroll-behavior: smooth;
  scrollbar-color: var(--science-border) transparent;
}
.ai-chat-empty {
  display: grid;
  height: 100%;
  min-height: 0;
  place-items: center;
  align-content: center;
  padding: 10px;
  color: var(--science-muted);
  text-align: center;
}
.answer-workspace .ai-chat-empty p { max-width: 36ch; margin: 3px 0 0; color: var(--science-muted); font-size: 15px; }
.ai-chat-empty-mark { color: var(--science-accent); font-size: 20px; }

.ai-message {
  width: fit-content;
  max-width: 94%;
  margin: 11px 0;
  animation: ai-message-enter 180ms ease-out both;
}
.ai-message--assistant { width: 100%; max-width: 100%; }
.ai-message--user { margin-left: auto; }
.ai-message-label { margin: 0 5px 5px; color: var(--science-muted); font-size: 13px; font-weight: 600; }
.ai-message--user .ai-message-label { text-align: right; }
.ai-message-body {
  min-width: 0;
  max-width: 100%;
  padding: 12px 14px;
  border: 1px solid var(--science-border);
  border-radius: 13px 13px 13px 4px;
  background: var(--ai-surface);
  color: var(--science-text);
  font-weight: 400;
  line-height: 1.62;
  overflow-wrap: anywhere;
  white-space: pre-wrap;
}
.ai-message--assistant .ai-message-body { padding: 8px 4px; border: 0; border-radius: 0; background: transparent; }
.ai-message--user .ai-message-body {
  border-color: color-mix(in srgb, var(--science-accent) 48%, var(--science-border));
  border-radius: 13px 13px 4px 13px;
  background: color-mix(in srgb, var(--science-accent) 15%, var(--science-elevated));
}
.ai-message[data-streaming="false"] .ai-message-body { white-space: normal; }
.ai-message-body p { margin: 0 0 13px; color: var(--science-text); }
.ai-message-body p:last-child { margin-bottom: 0; }
.ai-message-body h1, .ai-message-body h2, .ai-message-body h3, .ai-message-body h4, .ai-message-body h5, .ai-message-body h6 { margin: 16px 0 7px; color: var(--science-text); line-height: 1.3; }
.ai-message-body h1 { font-size: 1.35em; }
.ai-message-body h2 { font-size: 1.35em; }
.ai-message-body h3 { font-size: 1.18em; }
.ai-message-body strong { color: var(--science-text); font-weight: 750; }
.ai-message-body em { font-style: italic; }
.ai-message-body ul, .ai-message-body ol { margin: 9px 0 13px; padding-left: 26px; }
.ai-message-body li + li { margin-top: 6px; }
.ai-message-body li > ul, .ai-message-body li > ol { margin-block: 4px; }
.ai-message-body code { padding: 1px 4px; border-radius: 4px; background: rgba(0, 0, 0, .24); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: .92em; }
.ai-message-body pre { max-width: 100%; margin: 9px 0; padding: 10px; overflow-x: auto; border-radius: 8px; background: #080b11; white-space: pre; }
.ai-message-body pre code { padding: 0; background: transparent; }
.ai-message-body a { color: var(--science-accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }
.ai-message-body blockquote { margin: 10px 0; padding: 7px 12px; border-left: 3px solid var(--science-accent); background: color-mix(in srgb, var(--science-accent) 7%, transparent); color: var(--science-muted); }
.ai-message-body blockquote p { color: inherit; }
.ai-message-body table { display: block; width: max-content; max-width: 100%; margin: 12px 0; overflow-x: auto; border-spacing: 0; border-collapse: collapse; }
.ai-message-body th, .ai-message-body td { min-width: 96px; padding: 7px 9px; border: 1px solid var(--science-border); text-align: left; vertical-align: top; }
.ai-message-body th { background: color-mix(in srgb, var(--science-elevated) 76%, transparent); font-weight: 700; }
.ai-math { max-width: 100%; }
.ai-math--inline { display: inline-block; vertical-align: -.12em; }
.ai-math--display { display: block; margin: 12px 0; padding: 9px 10px 11px; overflow-x: auto; overflow-y: hidden; border: 1px solid var(--science-border); border-radius: 9px; background: color-mix(in srgb, var(--science-elevated) 52%, transparent); text-align: center; overscroll-behavior-inline: contain; }
.ai-math--display > .katex-display { width: max-content; min-width: 100%; margin: 0; }
.ai-math-paragraph { margin-block: 8px !important; }
.ai-math--error { color: var(--science-warning); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; white-space: pre-wrap; }
.ai-message-error { margin: 8px 4px 0; color: var(--science-warning); font-size: 14px; }

.ai-stream-activity { display: inline-flex; align-items: center; height: 19px; margin: 4px 0 0 10px; color: var(--science-accent); }
.ai-sparkle { display: inline-block; font-size: 13px; animation: ai-sparkle 1.8s ease-in-out infinite; }
.ai-caret { display: inline-block; width: 2px; height: 14px; margin-left: 6px; border-radius: 2px; background: currentColor; animation: ai-caret 900ms steps(1, end) infinite; }

.ai-jump-latest {
  position: absolute;
  right: 8px;
  bottom: 12px;
  min-height: 34px;
  padding: 5px 10px;
  border: 1px solid var(--ai-border);
  border-radius: 999px;
  background: var(--science-elevated);
  box-shadow: 0 5px 16px rgba(0, 0, 0, .28);
  color: var(--science-text);
  font-size: 13px;
  font-weight: 600;
}

.ai-quick-actions { display: flex; position: relative; z-index: 2; flex: 0 0 auto; gap: 8px; margin: 8px 0 10px; overflow-x: auto; scrollbar-width: none; }
.ai-quick-actions[hidden] { display: none; }
.ai-quick-actions::-webkit-scrollbar { display: none; }
.ai-quick-button {
  flex: 0 0 auto;
  min-height: 38px;
  padding: 6px 10px;
  border: 1px solid var(--science-border);
  border-radius: 999px;
  background: transparent;
  color: var(--science-muted);
  font-size: 13px;
  font-weight: 500;
}
.ai-quick-button:hover { border-color: var(--science-accent); color: var(--science-text); }

.ai-composer {
  position: relative;
  z-index: 2;
  display: flex;
  align-items: flex-end;
  gap: 8px;
  flex: 0 0 auto;
  padding: 7px;
  border: 1px solid var(--science-border);
  border-radius: 13px;
  background: var(--science-elevated);
  transition: border-color 150ms ease, box-shadow 150ms ease;
}
.ai-composer:focus-within { border-color: var(--science-accent); box-shadow: 0 0 0 3px color-mix(in srgb, var(--science-accent) 14%, transparent); }
.ai-composer-input {
  display: block;
  width: auto;
  min-width: 0;
  min-height: 48px;
  max-height: 128px;
  padding: 11px 7px 8px;
  flex: 1 1 auto;
  resize: none;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--science-text);
  font-size: 16px;
  line-height: 1.5;
}
.ai-composer-input::placeholder { color: color-mix(in srgb, var(--science-muted) 78%, transparent); }
.ai-composer-controls { display: flex; flex: 0 0 auto; align-items: center; justify-content: flex-end; gap: 7px; padding: 0; }
.ai-send-button, .ai-stop-button {
  min-height: 44px;
  padding: 7px 14px;
  border-radius: 9px;
  font-size: 14px;
  font-weight: 600;
}
.ai-send-button { border: 1px solid transparent; background: var(--science-accent); color: var(--science-accent-ink); }
.ai-stop-button { border: 1px solid var(--science-border); background: var(--science-surface); color: var(--science-text); }

@keyframes ai-message-enter {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes ai-sparkle {
  0%, 100% { opacity: .55; transform: rotate(0deg) scale(.88); }
  50% { opacity: 1; transform: rotate(90deg) scale(1.08); }
}
@keyframes ai-caret { 0%, 45% { opacity: 1; } 46%, 100% { opacity: 0; } }

.review-list { display: grid; gap: 12px; }
.review-item { padding: 18px; border: 1px solid var(--science-border); border-radius: var(--card-radius); background: var(--science-surface); }
.review-item h2 { margin: 0 0 8px; font-size: 17px; }
.review-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.review-source { min-width: 0; }
.review-source iframe { width: 100%; height: 440px; border: 1px solid var(--science-border); border-radius: var(--control-radius); background: var(--science-elevated); }
.crop-review-image { display: block; width: 100%; max-height: 700px; object-fit: contain; border: 1px solid var(--science-border); border-radius: var(--control-radius); background: #fff; }
.crop-add-form { display: flex; flex-wrap: wrap; align-items: end; gap: 10px; margin-bottom: 18px; }
.crop-add-form h2, .crop-add-form p { flex-basis: 100%; }
.crop-add-form input { min-height: 44px; padding: 8px 10px; border: 1px solid var(--science-border); border-radius: var(--control-radius); background: var(--science-bg); color: var(--science-text); }
.review-editor { display: grid; gap: 10px; }
.review-editor textarea { min-height: 100px; }

.filter-trigger { display: none; }

.dialog-backdrop {
  position: fixed;
  z-index: 9000;
  inset: 0;
  display: flex;
  justify-content: center;
  align-items: flex-end;
  padding: 12px;
  background: rgba(5, 8, 13, .88);
}
.filter-dialog {
  width: min(100%, 560px);
  max-height: min(84vh, 760px);
  overflow: auto;
  padding: 20px;
  border: 1px solid var(--science-border);
  border-radius: var(--panel-radius) var(--panel-radius) 0 0;
  background: var(--science-elevated);
}
.dialog-heading { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 16px; }
.dialog-heading h2 { margin: 0; font-size: 20px; }
.dialog-actions { position: sticky; bottom: -20px; display: flex; gap: 10px; margin: 20px -20px -20px; padding: 14px 20px calc(14px + env(safe-area-inset-bottom)); border-top: 1px solid var(--science-border); background: var(--science-elevated); }
.dialog-actions .primary-button { flex: 1; }

.science-footer { padding: 28px clamp(12px, 3vw, 34px); border-top: 1px solid var(--science-border); color: var(--science-muted); text-align: center; }
.footer-links { display: flex; flex-wrap: wrap; justify-content: center; gap: 8px 18px; }
.science-footer a { color: var(--science-muted); font-size: 13px; }
.footer-support { margin-top: 18px; }
.footer-support p { margin: 0 0 8px; font-size: 13px; }

.sr-status, .sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

@media (max-width: 1100px) {
  .viewer-zoom-status { display: none; }
  .ai-tutor-panel { padding: 13px; }
}

@media (min-width: 768px) and (max-width: 1180px) {
  body.study-mode .science-command-bar { display: none; }
  body.study-mode .science-main {
    padding:
      max(3px, env(safe-area-inset-top))
      max(6px, env(safe-area-inset-right))
      max(5px, env(safe-area-inset-bottom))
      max(6px, env(safe-area-inset-left));
  }
  .study-shell { grid-template-rows: 44px minmax(0, 1fr); }
  .detail-header { display: flex; min-height: 44px; padding: 0; align-items: center; border-bottom: 0; }
  .back-link { display: inline-flex; min-height: 44px; margin: 0; padding: 0 4px; align-items: center; font-size: 13px; }
  .question-meta-row, .study-nav { display: none; }
  .detail-grid { padding-top: 0; }
  .question-viewer-toolbar { min-height: 48px; padding: 2px 7px; gap: 5px; }
  .viewer-tool { min-height: 44px; padding: 6px 9px; }
  .source-citation { min-height: 28px; max-height: 28px; padding: 3px 9px; flex-wrap: nowrap; gap: 0; overflow: hidden; font-size: 11px; }
  .source-citation-full,
  .source-citation .secondary-button,
  .source-citation .quiet-button { display: none; }
  .source-citation .source-citation-compact { display: block; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
  .ai-tutor-panel { padding: 8px 9px 7px; border-radius: 13px; }
  .ai-tutor-header { min-height: 44px; padding-bottom: 4px; gap: 7px; }
  .ai-tutor-header h3 { font-size: 21px; }
  .ai-tutor-mark { width: 32px; height: 32px; }
  .ai-collapse-button { min-height: 44px; padding-block: 5px; }
  .ai-tutor-body { padding-top: 3px; }
  .ai-chat-thread { padding: 2px 4px 18px; }
  .ai-quick-actions { margin: 3px 0 4px; gap: 5px; }
  .ai-quick-button { min-height: 44px; padding: 6px 8px; font-size: 12px; }
  .ai-composer { margin: 0; padding: 4px; border-radius: 11px; }
  .ai-composer-input { min-height: 44px; padding: 8px 5px 6px; }
  .answer-tools { top: 5px; right: 91px; }
  .answer-tools summary { min-height: 44px; }
}

@media (max-width: 767px) {
  .study-shell { grid-template-rows: auto auto minmax(0, 1fr) auto; }
  .detail-mobile-switcher {
    display: grid;
    margin-top: 7px;
    padding: 3px;
    grid-template-columns: 1fr 1fr;
    gap: 3px;
    border: 1px solid var(--science-border);
    border-radius: 11px;
    background: var(--science-surface);
  }
  .detail-mobile-tab {
    min-height: 42px;
    border: 0;
    border-radius: 8px;
    background: transparent;
    color: var(--science-muted);
    font-weight: 700;
  }
  .detail-mobile-tab[aria-selected="true"] { background: var(--science-elevated); color: var(--science-text); box-shadow: inset 0 0 0 1px var(--science-border); }
  .detail-grid { grid-template-columns: minmax(0, 1fr); padding-top: 7px; }
  .detail-split-handle { display: none; }
  .detail-grid[data-mobile-pane="question"] .answer-workspace,
  .detail-grid[data-mobile-pane="rishai"] .question-pane { display: none; }
}

@media (max-width: 800px) {
  .science-command-bar { gap: 8px; }
  .science-home-full { display: none; }
  .science-home-compact { display: inline; }
  .session-name { display: none; }
  .bank-layout { display: block; }
  .filter-rail { display: none; }
  .filter-trigger { display: inline-flex; align-items: center; justify-content: center; }
  .question-card { grid-template-columns: minmax(0, 1fr); }
  .question-card-thumbnail { width: 100%; height: 150px; object-fit: contain; }
  .question-open { align-self: auto; min-height: 44px; display: inline-flex; align-items: center; }
  .question-image-viewer { border-radius: 12px; }
  .question-image-page { padding: 8px; }
  .review-grid { grid-template-columns: 1fr; }
}

@media (max-width: 520px) {
  .science-command-bar { flex-wrap: wrap; padding-block: 6px; }
  .subject-mark { order: 1; }
  .science-command-bar .rs-global-search-trigger--embedded { order: 3; }
  .workspace-nav { order: 3; width: calc(100% - 52px); height: 40px; }
  .workspace-nav a { flex: 1; justify-content: center; min-height: 40px; }
  .session { order: 2; }
  .science-main { padding-top: 22px; }
  body.study-mode .science-main { padding: 6px max(6px, env(safe-area-inset-right)) max(7px, env(safe-area-inset-bottom)) max(6px, env(safe-area-inset-left)); }
  .page-heading p { font-size: 14px; }
  .search-row { flex-wrap: wrap; }
  .search-control { flex-basis: 100%; }
  .search-shortcut { display: none; }
  .filter-trigger { flex: 1; }
  .question-card { padding: 15px; }
  .result-time { display: none; }
  .topic-children { grid-template-columns: 1fr; }
  .study-nav { align-items: stretch; }
  .study-nav a { flex: 1; width: auto; text-align: center; }
  .answer-workspace { padding: 0; }
  .answer-workspace .answer-tools { right: 13px; }
  .ai-tutor-panel { padding: 13px; border-radius: 12px; }
  .ai-tutor-header h3 { font-size: 22px; }
  .ai-collapse-button { display: none; }
  .ai-composer { padding-bottom: max(7px, env(safe-area-inset-bottom)); }
  .ai-message { max-width: 97%; }
  .worksheet-selection-toolbar {
    right: max(8px, env(safe-area-inset-right));
    bottom: max(8px, env(safe-area-inset-bottom));
    left: max(8px, env(safe-area-inset-left));
    width: auto;
    max-width: none;
    min-height: 0;
    padding: 9px;
    flex-direction: column;
    align-items: stretch;
    gap: 7px;
    transform: none;
  }
  .worksheet-selection-count { text-align: center; }
  .worksheet-selection-actions { display: grid; grid-template-columns: 1fr 1fr; }
  .worksheet-selection-actions button { min-width: 0; padding-inline: 8px; white-space: normal; }
  body.worksheet-selection-mode .science-main { padding-bottom: 190px; }
  .worksheet-preview-chrome { width: calc(100% - 20px); padding-block: 10px; }
  .worksheet-preview-heading { align-items: stretch; flex-direction: column; }
  .worksheet-preview-actions { display: grid; grid-template-columns: 1fr 1fr; }
  .worksheet-preview-settings { grid-template-columns: 1fr; gap: 7px; }
  .worksheet-organizer-actions .icon-button { width: 36px; }
  .worksheet-remove-button { padding-inline: 7px; }
  .worksheet-pages { width: calc(100% - 16px); padding-top: 12px; }
  .worksheet-print-page { min-height: 0; padding: 24px 18px 18px; }
  .worksheet-document-title { font-size: 20pt; }
  .worksheet-question-image { max-height: 72vh; }
}

@media (max-width: 520px) {
  .rishai-support-interstitial { padding: 10px; }
  .rishai-support-dialog-card { padding: 19px 16px; }
  .rishai-support-actions { flex-direction: column; }
  .rishai-support-primary, .rishai-support-secondary { width: 100%; min-height: 48px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; }
  .ai-message, .ai-sparkle, .ai-caret { animation: none !important; }
  .ai-chat-thread { scroll-behavior: auto !important; }
  .question-image-pages { transition: none !important; }
  .ai-tutor-content { transition: none !important; }
}

@media print {
  @page { size: A4 portrait; margin: 0; }

  html, body {
    width: 210mm !important;
    min-width: 0 !important;
    margin: 0 !important;
    padding: 0 !important;
    background: #fff !important;
    color: #111 !important;
    print-color-adjust: exact;
    -webkit-print-color-adjust: exact;
  }
  body > :not(.worksheet-preview-root) { display: none !important; }
  .worksheet-preview-root {
    position: static !important;
    display: block !important;
    width: 210mm !important;
    overflow: visible !important;
    background: #fff !important;
    color: #111 !important;
  }
  .worksheet-preview { min-height: 0 !important; }
  .worksheet-preview-chrome { display: none !important; }
  .worksheet-pages {
    display: block !important;
    width: 210mm !important;
    margin: 0 !important;
    padding: 0 !important;
  }
  .worksheet-preview-empty { display: none !important; }
  .worksheet-print-page {
    width: 210mm !important;
    height: 296.8mm !important;
    min-height: 296.8mm !important;
    max-height: 296.8mm !important;
    margin: 0 !important;
    padding: 14mm 15mm 12mm !important;
    overflow: hidden !important;
    break-after: page;
    break-inside: avoid-page;
    page-break-after: always;
    page-break-inside: avoid;
    border: 0 !important;
    border-radius: 0 !important;
    background: #fff !important;
    color: #111 !important;
    box-shadow: none !important;
  }
  .worksheet-print-page:last-child { break-after: auto; page-break-after: auto; }
  .worksheet-page-body { min-height: 0 !important; overflow: hidden !important; }
  .worksheet-question-figure { min-height: 0 !important; overflow: hidden !important; }
  .worksheet-question-image { width: 100% !important; height: 100% !important; max-height: none !important; object-fit: contain !important; }
  .worksheet-page-footer { break-inside: avoid; page-break-inside: avoid; }
}

/* Physics: Amber Luxe yellow palette. */
body[data-science-subject="physics"] {
  --science-bg: #0f172a;
  --science-bg-overlay: rgba(15, 18, 20, 0.72);
  --science-surface: rgba(39, 34, 17, 0.7);
  --science-elevated: rgba(58, 46, 13, 0.72);
  --science-border: rgba(252, 196, 25, 0.36);
  --science-text: #fff8cc;
  --science-muted: #e7d99f;
  --science-focus: #ffe066;
  --science-accent: #fcc419;
  --science-accent-ink: #241800;
}

body[data-science-subject="physics"] .subject-mark,
body[data-science-subject="physics"] .primary-button {
  box-shadow: 0 8px 24px rgba(252, 196, 25, 0.22);
}

body[data-science-subject="physics"] :is(button, a, input, select, textarea):focus-visible {
  outline-color: #ffe066;
}

/* Compact study workspace: keep the paper visible and dock RishAI in its own pane. */
body.study-mode .answer-workspace {
  position: relative;
  min-width: 0;
}

body.study-mode .answer-workspace.is-rishai-open {
  overflow: hidden;
}

body.study-mode .ai-tutor-panel {
  position: absolute;
  inset: 0;
  z-index: 12;
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
  margin: 0;
  overflow: hidden;
  transition:
    inset 360ms cubic-bezier(.22, 1, .36, 1),
    width 360ms cubic-bezier(.22, 1, .36, 1),
    height 360ms cubic-bezier(.22, 1, .36, 1),
    border-radius 360ms ease;
}

body.study-mode .ai-tutor-panel[data-collapsed="true"] {
  inset: auto 12px 12px auto;
  width: 52px;
  height: 52px;
  border-radius: 12px;
  cursor: pointer;
}

body.study-mode .ai-tutor-panel[data-collapsed="true"] .ai-tutor-header {
  position: relative;
  display: grid;
  grid-template-columns: 1fr;
  min-height: 50px;
  padding: 4px;
  place-items: center;
  cursor: pointer;
}

body.study-mode .ai-tutor-mark {
  display: block;
  width: 30px;
  height: 30px;
  flex: 0 0 30px;
  border: 0;
  border-radius: 8px;
  object-fit: cover;
}

body.study-mode .ai-tutor-panel[data-collapsed="true"] .ai-tutor-mark {
  width: 42px;
  height: 42px;
}

body.study-mode .ai-tutor-panel[data-collapsed="true"] .ai-tutor-header h3 {
  display: none;
}

body.study-mode .ai-tutor-panel[data-collapsed="true"] .ai-collapse-button {
  position: absolute;
  inset: 0;
  display: block;
  width: 100%;
  height: 100%;
  min-height: 0;
  padding: 0;
  opacity: 0;
  cursor: pointer;
}

body.study-mode .ai-tutor-panel:not([data-collapsed="true"]) .ai-tutor-body,
body.study-mode .ai-tutor-panel:not([data-collapsed="true"]) .ai-tutor-content {
  flex: 1;
  min-height: 0;
}

body.study-mode .ai-tutor-panel:not([data-collapsed="true"]) .ai-tutor-content {
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

body.study-mode .ai-tutor-panel:not([data-collapsed="true"]) .ai-chat-shell {
  flex: 1;
  min-height: 0;
}

body.study-mode .source-citation {
  min-height: 50px;
  justify-content: flex-end;
  gap: 8px;
  padding: 7px 10px;
}

body.study-mode .source-citation .quiet-button:disabled {
  display: none;
}

body.study-mode .answer-tools {
  position: static !important;
  width: auto;
  margin: 0 12px;
  border: 0 !important;
}

body.study-mode .answer-tools > summary {
  position: static !important;
  width: 100%;
  min-height: 40px;
}

@media (max-width: 1100px) {
  body.study-mode .study-shell {
    padding-inline: 8px;
  }

  body.study-mode .detail-header {
    gap: 4px;
    margin-bottom: 6px;
  }

  body.study-mode .question-meta-row {
    gap: 4px;
    font-size: 0.82rem;
  }

  body.study-mode .question-viewer-toolbar {
    gap: 6px;
    padding: 7px;
  }

  body.study-mode .viewer-tool {
    min-height: 38px;
    padding-inline: 10px;
  }
}

@media (max-width: 900px) {
  body.study-mode .detail-mobile-switcher {
    display: flex;
  }

  body.study-mode .detail-grid {
    display: block;
    min-height: 0;
  }

  body.study-mode .detail-split-handle {
    display: none;
  }

  body.study-mode .detail-grid[data-mobile-pane="question"] .question-pane {
    display: block;
  }

  body.study-mode .detail-grid[data-mobile-pane="question"] .answer-workspace {
    display: none;
  }

  body.study-mode .detail-grid[data-mobile-pane="rishai"] .question-pane {
    display: none;
  }

  body.study-mode .detail-grid[data-mobile-pane="rishai"] .answer-workspace {
    display: flex;
  }
}

@media (prefers-reduced-motion: reduce) {
  body.study-mode .ai-tutor-panel {
    transition: none;
  }
}