:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --text: #1c1f26;
  --muted: #6b7280;
  --border: #e2e5ea;
  --accent: #2563eb;
  --accent-contrast: #ffffff;
  --success: #16a34a;
  --danger: #dc2626;
  --warn: #b45309;
  --radius: 10px;

  --strong-color: #b45309;
  --mark-bg: #fde68a;
  --mark-color: #1c1f26;

  --callout-tip: #2563eb;
  --callout-warning: #d97706;
  --callout-success: #16a34a;
  --callout-danger: #dc2626;
  --callout-key: #7c3aed;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14161b;
    --surface: #1d2027;
    --text: #e7e9ee;
    --muted: #9aa1ad;
    --border: #2c3038;
    --accent: #5b8def;
    --accent-contrast: #0b1020;

    --strong-color: #fbbf24;
    --mark-bg: #7c5e10;
    --mark-color: #fde68a;

    --callout-tip: #5b8def;
    --callout-warning: #f59e0b;
    --callout-success: #34d399;
    --callout-danger: #f87171;
    --callout-key: #a78bfa;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}

a { color: var(--accent); }

.site-header {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
  flex-wrap: wrap;
}
.brand { font-weight: 700; font-size: 18px; text-decoration: none; color: var(--text); }
#nav { display: flex; align-items: center; gap: 14px 20px; flex: 1; flex-wrap: wrap; justify-content: space-between; }
#nav a { text-decoration: none; color: var(--text); font-size: 14px; }
.nav-links { display: flex; align-items: center; gap: 14px; }
.nav-user-group { display: flex; align-items: center; gap: 10px; min-width: 0; }
.nav-user {
  color: var(--muted);
  font-size: 13px;
  max-width: 45vw;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.link-btn {
  background: none; border: none; color: var(--accent); cursor: pointer; font-size: 14px; padding: 0;
  white-space: nowrap;
}

main#app {
  max-width: 880px;
  margin: 0 auto;
  padding: 24px 16px 64px;
}

@media (max-width: 480px) {
  .site-header { padding: 10px 14px; gap: 10px; }
  .brand { font-size: 16px; }
  main#app { padding: 16px 12px 48px; }
  .nav-user { max-width: 40vw; }
}

.page-header { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-bottom: 16px; flex-wrap: wrap; }
.link-back { font-size: 14px; }

.muted { color: var(--muted); }
.muted.small { font-size: 13px; }
.error { color: var(--danger); }
.success { color: var(--success); }

.badge {
  display: inline-block;
  padding: 4px 10px;
  border-radius: 999px;
  background: #fef3c7;
  color: #92400e;
  font-size: 13px;
  white-space: nowrap;
}
.badge.small { padding: 2px 8px; font-size: 11px; }
@media (prefers-color-scheme: dark) {
  .badge { background: #3a2f12; color: #fbbf24; }
}

.notice {
  display: block;
  padding: 10px 14px;
  border-radius: var(--radius);
  background: #fef3c7;
  color: #92400e;
  font-size: 13px;
  text-align: left;
  border-left: 4px solid #d97706;
}
@media (prefers-color-scheme: dark) {
  .notice { background: #3a2f12; color: #fbbf24; border-left-color: #d97706; }
}

button, .button {
  font-family: inherit;
  font-size: 14px;
  padding: 9px 16px;
  border-radius: var(--radius);
  border: 1px solid var(--accent);
  background: var(--accent);
  color: var(--accent-contrast);
  cursor: pointer;
  text-decoration: none;
  display: inline-block;
}
button:disabled { opacity: 0.6; cursor: default; }
button.btn-danger { background: var(--danger); border-color: var(--danger); }
button.btn-success { background: var(--success); border-color: var(--success); }

/* --- Auth --- */
.auth-screen { max-width: 360px; margin: 40px auto; text-align: center; }
.stack { display: flex; flex-direction: column; gap: 12px; text-align: left; margin-top: 20px; }
.stack label { display: flex; flex-direction: column; gap: 4px; font-size: 14px; }
.stack input {
  padding: 9px 12px; border-radius: var(--radius); border: 1px solid var(--border);
  background: var(--surface); color: var(--text); font-size: 15px;
}

/* --- Home / module grid --- */
.module-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 14px; }
.module-card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px; text-decoration: none; color: var(--text); display: flex; flex-direction: column; gap: 6px;
}
.module-card h2 { font-size: 17px; margin: 0; }

.empty-state { text-align: center; padding: 40px 20px; }

/* --- Progress bar --- */
.progress-bar { background: var(--border); border-radius: 999px; height: 8px; overflow: hidden; }
.progress-bar-fill { background: var(--accent); height: 100%; }

/* --- Upload --- */
.dropzone {
  border: 2px dashed var(--border); border-radius: var(--radius); padding: 40px 20px;
  text-align: center; background: var(--surface);
}
.dropzone-active { border-color: var(--accent); background: color-mix(in srgb, var(--accent) 8%, var(--surface)); }
.preview-card { margin-top: 16px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; }
.preview-card.preview-error { border-color: var(--danger); }
.preview-card.preview-ok { border-color: var(--success); }
.preview-summary { font-weight: 600; }
.issue-list { margin: 8px 0 0; padding-left: 20px; }
.issue-list.error li { color: var(--danger); }
.issue-list.warn li { color: var(--warn); }

/* --- Chapter list --- */
.chapter-list { list-style: none; padding: 0; margin: 16px 0; display: flex; flex-direction: column; gap: 6px; }
.chapter-row {
  display: flex; align-items: flex-start; gap: 10px; background: var(--surface);
  border: 1px solid var(--border); border-radius: var(--radius); padding: 12px 14px;
}
.chapter-row input[type="checkbox"] { margin-top: 4px; flex-shrink: 0; }
.chapter-row a { flex: 1; text-decoration: none; color: var(--text); line-height: 1.4; }
.chapter-number { color: var(--muted); }
.chapter-type-badge {
  display: inline-block; margin-left: 8px; font-size: 11px; color: var(--muted);
  border: 1px solid var(--border); border-radius: 999px; padding: 1px 8px; white-space: nowrap; vertical-align: middle;
}

/* --- Tabs --- */
.tabs { display: flex; gap: 4px; border-bottom: 1px solid var(--border); margin-bottom: 16px; overflow-x: auto; }
.tab-btn {
  background: none; border: none; border-bottom: 2px solid transparent; color: var(--muted);
  padding: 10px 14px; border-radius: 0; white-space: nowrap;
}
.tab-btn.active { color: var(--accent); border-bottom-color: var(--accent); font-weight: 600; }
.tab-content { min-height: 200px; }

.theory-content h2, .conspect-content h2 { margin-top: 28px; }
.theory-content strong, .conspect-content strong { color: var(--strong-color); }
.theory-content mark, .conspect-content mark {
  background: var(--mark-bg); color: var(--mark-color); padding: 1px 4px; border-radius: 4px;
}

/* Врезки-цитаты: серая по умолчанию, цветная если markdown.js распознал эмодзи (💡⚠️✅❗📌) */
.callout {
  margin: 16px 0; padding: 10px 16px; background: var(--surface); border-left: 4px solid var(--accent); border-radius: 6px;
}
.callout-tip { border-left-color: var(--callout-tip); background: color-mix(in srgb, var(--callout-tip) 10%, var(--surface)); }
.callout-warning { border-left-color: var(--callout-warning); background: color-mix(in srgb, var(--callout-warning) 10%, var(--surface)); }
.callout-success { border-left-color: var(--callout-success); background: color-mix(in srgb, var(--callout-success) 10%, var(--surface)); }
.callout-danger { border-left-color: var(--callout-danger); background: color-mix(in srgb, var(--callout-danger) 10%, var(--surface)); }
.callout-key { border-left-color: var(--callout-key); background: color-mix(in srgb, var(--callout-key) 10%, var(--surface)); }

.theory-content table, .conspect-content table { display: block; overflow-x: auto; border-collapse: collapse; width: 100%; margin: 12px 0; }
.theory-content th, .theory-content td, .conspect-content th, .conspect-content td { border: 1px solid var(--border); padding: 6px 10px; text-align: left; }
.terms-table { display: block; overflow-x: auto; }

.conspect-outline { padding-left: 20px; }
.terms-table { border-collapse: collapse; width: 100%; margin-top: 8px; }
.terms-table td { border: 1px solid var(--border); padding: 8px 10px; vertical-align: top; }
.terms-table .term { font-weight: 600; width: 30%; }

.practice-task, .practicum-task {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px; margin-bottom: 16px;
}
.worked-example { margin: 10px 0; }
.practice-answer { width: 100%; min-height: 80px; margin-top: 10px; border-radius: var(--radius); border: 1px solid var(--border); padding: 8px; background: var(--bg); color: var(--text); font-family: inherit; }

.test-question {
  border: 1px solid var(--border); border-radius: var(--radius); padding: 12px 16px; margin-bottom: 12px; background: var(--surface);
}
.test-question.answer-correct { border-color: var(--success); }
.test-question.answer-wrong { border-color: var(--danger); }
.option-label { display: block; padding: 4px 0; cursor: pointer; }
.explanation-slot { margin-top: 8px; font-size: 14px; }
.test-score { font-size: 18px; font-weight: 600; }

.flashcard {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  min-height: 160px; display: flex; flex-direction: column; align-items: center; justify-content: center; text-align: center;
  padding: 24px; font-size: 18px; margin-bottom: 8px; cursor: pointer; user-select: none;
  transition: border-color 0.15s, background 0.15s;
}
.flashcard:hover, .flashcard:focus-visible { border-color: var(--accent); }
.flashcard-front { font-weight: 600; }
.flashcard-back { color: var(--accent); margin-top: 14px; padding-top: 14px; border-top: 1px dashed var(--border); }
#flashcard-hint { text-align: center; margin-bottom: 12px; }
.flashcard-controls { display: flex; gap: 10px; justify-content: center; }