:root {
  --bg: #f5f6f9;
  --surface: #ffffff;
  --surface-2: #eef1f6;
  --text: #1b2230;
  --muted: #687386;
  --border: #dde2ea;
  --accent: #1f3a68;
  --accent-2: #2f5ea8;
  --accent-soft: #e3ebf8;
  --again: #c0392b;
  --hard: #c27c0e;
  --good: #2e8b57;
  --easy: #2f6fb5;
  --shadow: 0 1px 2px rgba(20, 30, 50, .06), 0 4px 16px rgba(20, 30, 50, .06);
  --radius: 14px;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12151b;
    --surface: #1b2029;
    --surface-2: #232a35;
    --text: #e6e9ef;
    --muted: #97a1b3;
    --border: #2e3644;
    --accent: #8fb3ff;
    --accent-2: #a9c4ff;
    --accent-soft: #24324d;
    --again: #ff7b6b;
    --hard: #f0b350;
    --good: #5fd08f;
    --easy: #7fb2ff;
    --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 4px 16px rgba(0, 0, 0, .25);
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  -webkit-text-size-adjust: 100%;
}

a { color: var(--accent-2); }
h1, h2, h3 { line-height: 1.25; margin: 0 0 .5em; }
h1 { font-size: 1.6rem; }
h2 { font-size: 1.2rem; }
.muted { color: var(--muted); }
.small { font-size: .875rem; }

/* ---------- barre du haut ---------- */
.topbar {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  padding: 10px 16px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}
.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; color: var(--text); text-decoration: none; }
.logo {
  display: inline-grid; place-items: center; width: 30px; height: 30px; border-radius: 8px;
  background: var(--accent); color: var(--surface); font-family: Georgia, serif; font-size: 18px;
}
.topbar nav { display: flex; gap: 14px; }
.topbar nav a { color: var(--muted); text-decoration: none; font-size: .95rem; }
.topbar nav a:hover, .topbar nav a.active { color: var(--text); }

main { max-width: 860px; margin: 0 auto; padding: 20px 16px 120px; }
.loading { color: var(--muted); text-align: center; padding: 40px 0; }

/* ---------- éléments communs ---------- */
.panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px;
}
.stack > * + * { margin-top: 14px; }
.row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.spacer { flex: 1; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  min-height: 42px; padding: 0 16px;
  border: 1px solid var(--border); border-radius: 10px;
  background: var(--surface); color: var(--text);
  font: inherit; font-weight: 600; cursor: pointer; text-decoration: none;
  transition: background .15s, border-color .15s, transform .05s;
}
.btn:hover { background: var(--surface-2); }
.btn:active { transform: translateY(1px); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--surface); }
.btn.primary:hover { filter: brightness(1.1); }
.btn.ghost { background: transparent; border-color: transparent; color: var(--muted); }
.btn[disabled] { opacity: .5; cursor: default; }
.btn kbd { font: 600 .7rem ui-monospace, monospace; opacity: .6; border: 1px solid currentColor; border-radius: 4px; padding: 0 4px; }

input[type=text], input[type=password] {
  min-height: 42px; padding: 0 12px; border-radius: 10px;
  border: 1px solid var(--border); background: var(--surface); color: var(--text); font: inherit;
  min-width: 0;
}
input:focus-visible, .btn:focus-visible, a:focus-visible { outline: 2px solid var(--accent-2); outline-offset: 2px; }

.pill {
  display: inline-flex; align-items: center; gap: 4px;
  padding: 2px 9px; border-radius: 999px; font-size: .8rem; font-weight: 600;
  background: var(--surface-2); color: var(--muted); white-space: nowrap;
}
.pill.due { background: color-mix(in srgb, var(--again) 15%, transparent); color: var(--again); }
.pill.new { background: var(--accent-soft); color: var(--accent-2); }
.pill.ok { background: color-mix(in srgb, var(--good) 15%, transparent); color: var(--good); }

.bar { height: 6px; border-radius: 3px; background: var(--surface-2); overflow: hidden; }
.bar > span { display: block; height: 100%; background: var(--good); border-radius: 3px; }

/* ---------- accueil ---------- */
.hero { display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }
.hero .big { font-size: 2.2rem; font-weight: 800; line-height: 1; }
.subject-title { margin: 30px 0 10px; font-size: .85rem; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); }
.chapters { display: grid; gap: 10px; margin-top: 20px; }
.subject-title + .chapters { margin-top: 0; }
.chapter-link {
  display: grid; grid-template-columns: auto 1fr; gap: 4px 14px; align-items: center;
  padding: 14px 16px; text-decoration: none; color: inherit;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  transition: border-color .15s, transform .1s;
}
.chapter-link:hover { border-color: var(--accent-2); }
.chapter-num {
  grid-row: span 2; width: 38px; height: 38px; border-radius: 10px; display: grid; place-items: center;
  background: var(--accent-soft); color: var(--accent-2); font-weight: 800;
}
.chapter-link .title { font-weight: 650; }
.chapter-link .meta { display: flex; gap: 6px; flex-wrap: wrap; align-items: center; }
.chapter-link .bar { grid-column: 2; margin-top: 4px; }

.name-banner { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.name-banner input { flex: 1; min-width: 160px; }

/* ---------- chapitre ---------- */
.crumbs { font-size: .9rem; margin-bottom: 10px; }
.crumbs a { text-decoration: none; }
.sections { display: grid; gap: 14px; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.section-card h2 { display: flex; align-items: center; gap: 8px; }
.section-card .icon { font-size: 1.2rem; }
.section-card .actions { display: grid; gap: 8px; margin-top: 14px; }

/* ---------- séance ---------- */
.session-head { display: flex; align-items: center; gap: 12px; margin-bottom: 14px; }
.session-head .bar { flex: 1; }
.session-head .bar > span { background: var(--accent-2); transition: width .3s; }
.flashcard { min-height: 260px; display: flex; flex-direction: column; padding: 22px; }
.flashcard .tags { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 14px; }
.flashcard .face { font-size: 1.12rem; overflow-x: auto; }
.flashcard .answer { border-top: 1px dashed var(--border); margin-top: 18px; padding-top: 18px; animation: reveal .2s ease-out; }
.flashcard .hint { margin-top: 14px; padding: 10px 14px; border-radius: 10px; background: var(--accent-soft); font-size: .98rem; }
.flashcard .hint b { display: block; margin-bottom: 2px; font-size: .85rem; }
@keyframes reveal { from { opacity: 0; transform: translateY(-4px); } to { opacity: 1; transform: none; } }

.controls {
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 5;
  padding: 12px 16px calc(12px + env(safe-area-inset-bottom));
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(8px);
  border-top: 1px solid var(--border);
}
.controls .inner { max-width: 860px; margin: 0 auto; display: flex; gap: 8px; }
.controls .btn { flex: 1; }
.grades { display: grid !important; grid-template-columns: repeat(4, 1fr); }
.grade { flex-direction: column; gap: 0; min-height: 56px; line-height: 1.2; padding: 6px 4px; }
.grade small { font-weight: 500; opacity: .8; font-size: .78rem; }
.grade.g1 { color: var(--again); border-color: color-mix(in srgb, var(--again) 40%, var(--border)); }
.grade.g2 { color: var(--hard); border-color: color-mix(in srgb, var(--hard) 40%, var(--border)); }
.grade.g3 { color: var(--good); border-color: color-mix(in srgb, var(--good) 40%, var(--border)); }
.grade.g4 { color: var(--easy); border-color: color-mix(in srgb, var(--easy) 40%, var(--border)); }

.done { text-align: center; padding: 36px 18px; }
.done .emoji { font-size: 3rem; }

/* ---------- parcourir ---------- */
.browse-card { padding: 0; overflow: hidden; }
.browse-card .q { padding: 14px 16px; }
.browse-card details { border-top: 1px solid var(--border); }
.browse-card summary { padding: 10px 16px; cursor: pointer; color: var(--accent-2); font-weight: 600; font-size: .9rem; }
.browse-card details > div { padding: 0 16px 14px; }
.browse-card .num { float: left; color: var(--muted); font-weight: 700; margin: .5em 8px 0 0; }

/* ---------- statistiques ---------- */
.kpis { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.kpi { text-align: center; padding: 14px 8px; }
.kpi b { display: block; font-size: 1.8rem; line-height: 1.1; }
.chart { display: flex; align-items: flex-end; gap: 3px; height: 110px; padding-top: 8px; }
.chart span { flex: 1; background: var(--accent-2); border-radius: 3px 3px 0 0; min-height: 2px; opacity: .85; }
.chart span.zero { background: var(--surface-2); opacity: 1; }
.progress-row { display: grid; grid-template-columns: 1fr auto; gap: 4px 12px; align-items: center; padding: 8px 0; border-bottom: 1px solid var(--border); }
.progress-row:last-child { border-bottom: 0; }
.progress-row .bar { grid-column: 1 / -1; }

/* ---------- tableaux (espace enseignant) ---------- */
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: .92rem; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { color: var(--muted); font-weight: 600; font-size: .8rem; text-transform: uppercase; letter-spacing: .04em; }
td.num, th.num { text-align: right; white-space: nowrap; }
.errors li { color: var(--again); }

code.token { font: .9rem ui-monospace, monospace; background: var(--surface-2); padding: 6px 10px; border-radius: 8px; word-break: break-all; }

/* ---------- contenu des cartes (Markdown + LaTeX) ---------- */
.md > :first-child { margin-top: 0; }
.md > :last-child { margin-bottom: 0; }
.md p { margin: .5em 0; }
.md ul, .md ol { padding-left: 1.4em; margin: .5em 0; }
.md code { font-family: ui-monospace, monospace; font-size: .9em; background: var(--surface-2); padding: 1px 5px; border-radius: 5px; }
.md pre { background: var(--surface-2); padding: 12px; border-radius: 10px; overflow-x: auto; }
.md pre code { background: none; padding: 0; }
.md table { width: auto; }
.md th { text-transform: none; letter-spacing: normal; font-size: inherit; color: inherit; }
.md .katex-display { overflow-x: auto; overflow-y: hidden; padding: 4px 0; }
.md img { max-width: 100%; }

@media (max-width: 560px) {
  h1 { font-size: 1.35rem; }
  .flashcard { padding: 18px 16px; }
  .flashcard .face { font-size: 1.05rem; }
  .topbar nav { gap: 10px; }
  .kpi b { font-size: 1.4rem; }
}

/* ---------- espace enseignant ---------- */
.admin-head { margin-bottom: 6px; }
.tabs { display: flex; gap: 4px; border-bottom: 1px solid var(--border); margin-bottom: 16px; overflow-x: auto; }
.tab { padding: 8px 14px; color: var(--muted); text-decoration: none; font-weight: 600; border-bottom: 2px solid transparent; margin-bottom: -1px; white-space: nowrap; }
.tab.active { color: var(--text); border-bottom-color: var(--accent-2); }

.admin-chapters { display: grid; margin-top: 8px; }
.admin-chapter {
  display: grid; grid-template-columns: auto 1fr auto auto; gap: 8px 14px; align-items: center;
  padding: 10px 0; border-bottom: 1px solid var(--border);
}
.admin-chapter:last-child { border-bottom: 0; }
.admin-chapter .title { color: var(--text); font-weight: 600; text-decoration: none; }
.admin-chapter .title:hover { text-decoration: underline; }

.switch { display: inline-flex; align-items: center; gap: 8px; cursor: pointer; user-select: none; }
.switch input { position: absolute; opacity: 0; width: 1px; height: 1px; }
.switch .slider {
  position: relative; width: 40px; height: 22px; border-radius: 11px; background: var(--border); transition: background .15s; flex: none;
}
.switch .slider::after {
  content: ""; position: absolute; top: 3px; left: 3px; width: 16px; height: 16px; border-radius: 50%;
  background: var(--surface); box-shadow: 0 1px 2px rgba(0,0,0,.25); transition: transform .15s;
}
.switch input:checked + .slider { background: var(--good); }
.switch input:checked + .slider::after { transform: translateX(18px); }
.switch input:focus-visible + .slider { outline: 2px solid var(--accent-2); outline-offset: 2px; }
.switch input:disabled + .slider { opacity: .6; }
.switch-label { font-size: .85rem; color: var(--muted); }
.admin-chapter .switch-label { display: none; }

.edit-section { margin-top: 26px; }
.edit-card { display: flex; gap: 10px; padding: 12px 14px; }
.edit-card-body { flex: 1; min-width: 0; overflow-x: auto; }
.edit-card-body summary { cursor: pointer; color: var(--accent-2); font-size: .85rem; font-weight: 600; margin-top: 6px; }
.edit-card-actions { display: flex; gap: 2px; align-items: flex-start; }
.btn.icon { min-height: 34px; width: 34px; padding: 0; }
.btn.danger:hover { color: var(--again); }
.hint { margin-top: 10px; padding: 10px 14px; border-radius: 10px; background: var(--accent-soft); font-size: .98rem; }
.hint b { display: block; margin-bottom: 2px; font-size: .85rem; }

.card-form { border-color: var(--accent-2); }
.card-form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.card-form label { display: grid; gap: 4px; font-weight: 600; font-size: .9rem; }
textarea, select {
  width: 100%; padding: 10px 12px; border-radius: 10px; border: 1px solid var(--border);
  background: var(--surface); color: var(--text); font: .92rem/1.45 ui-monospace, "SF Mono", Menlo, monospace; resize: vertical;
}
select { width: auto; min-height: 38px; padding: 0 10px; font: inherit; }
.preview-card { min-height: 0; box-shadow: none; background: var(--bg); }
.preview-card .answer { animation: none; }
kbd { font: 600 .75rem ui-monospace, monospace; border: 1px solid var(--border); border-radius: 4px; padding: 0 4px; }

@media (max-width: 720px) {
  .card-form-grid { grid-template-columns: 1fr; }
  .admin-chapter { grid-template-columns: auto 1fr; }
  .admin-chapter > .muted { grid-column: 2; }
  .admin-chapter .btn { grid-column: 1 / -1; }
}

/* ---------- réglages des révisions ---------- */
input[type=number] {
  min-height: 38px; width: 90px; padding: 0 10px; border-radius: 10px;
  border: 1px solid var(--border); background: var(--surface); color: var(--text); font: inherit;
}
.settings-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 16px; align-items: start; }
.settings-grid fieldset { margin: 0; }
.settings-grid legend { font-weight: 700; padding: 0 6px; }
.setting-fields { display: grid; gap: 8px; }
.setting { display: flex; justify-content: space-between; align-items: center; gap: 10px; }
.setting-input { display: inline-flex; align-items: center; gap: 6px; white-space: nowrap; }
.simulation { position: sticky; top: 70px; }
.simulation td.mastered { color: var(--good); font-weight: 600; }
@media (max-width: 760px) {
  .settings-grid { grid-template-columns: 1fr; }
  .simulation { position: static; }
}

/* ---------- aide ---------- */
.help h3 { font-size: 1rem; margin: 18px 0 6px; }
.help dl { margin: 0; }
.help dt { font-weight: 700; margin-top: 8px; }
.help dd { margin: 2px 0 0; }
.help-table td { vertical-align: middle; }
.grade-dot { display: inline-block; width: 10px; height: 10px; border-radius: 50%; margin-right: 6px; }
.grade-dot.g1 { background: var(--again); }
.grade-dot.g2 { background: var(--hard); }
.grade-dot.g3 { background: var(--good); }
.grade-dot.g4 { background: var(--easy); }

/* ---------- connexion ---------- */
.login { max-width: 440px; margin: 40px auto; text-align: center; padding: 32px 24px; }
.login-logo { width: 52px; height: 52px; font-size: 30px; border-radius: 14px; margin-bottom: 12px; }
.login .btn { margin-top: 8px; }
.login-error { color: var(--again); background: color-mix(in srgb, var(--again) 10%, transparent); padding: 10px 12px; border-radius: 10px; }