/* Style commun (élève + prof), repris de « Algebraträning kapitel 2 » : papier quadrillé, cartes, polices lisibles.
   Polices : Google Fonts (lien dans chaque page HTML). */
:root {
  --paper: #f6f8fb;
  --grid: #dfe6ef;
  --card: #ffffff;
  --ink: #1d2740;
  --muted: #5b6680;
  --line: #cfd8e6;
  --accent: #2f8a68;
  --accent-ink: #ffffff;
  --accent-soft: #e1f2ea;
  --good: #1f7a4d;
  --good-soft: #dcf3e6;
  --bad: #b3372f;
  --bad-soft: #fbe3e0;
  --hint-soft: #fff4cc;
  --hint-ink: #6b5200;
  --f-display: "Bricolage Grotesque", "Segoe UI", system-ui, sans-serif;
  --f-body: "Atkinson Hyperlegible", "Segoe UI", system-ui, sans-serif;
  --f-math: "STIX Two Text", "Cambria Math", "Times New Roman", serif;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #121826; --grid: #1c2536; --card: #1a2232; --ink: #e8edf6; --muted: #9aa6bd; --line: #2e3a50;
    --accent: #4cc293; --accent-ink: #0d1a14; --accent-soft: #173428; --good: #5fd39c; --good-soft: #163527;
    --bad: #ff8a7f; --bad-soft: #3a1e1c; --hint-soft: #3a3214; --hint-ink: #f3dc84; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #121826; --grid: #1c2536; --card: #1a2232; --ink: #e8edf6; --muted: #9aa6bd; --line: #2e3a50;
  --accent: #4cc293; --accent-ink: #0d1a14; --accent-soft: #173428; --good: #5fd39c; --good-soft: #163527;
  --bad: #ff8a7f; --bad-soft: #3a1e1c; --hint-soft: #3a3214; --hint-ink: #f3dc84; color-scheme: dark;
}
body {
  background-color: var(--paper);
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px;
  color: var(--ink);
  font: 17px/1.55 var(--f-body);
}
.wrap { max-width: 760px; margin: 0 auto; padding-block: 28px 48px; padding-left: max(16px, env(safe-area-inset-left, 0px)); padding-right: max(16px, env(safe-area-inset-right, 0px)); display: grid; gap: 20px; }
h1, h2, h3 { font-family: var(--f-display); text-wrap: balance; margin: 0; line-height: 1.15; }
h1 { font-size: clamp(1.9rem, 5vw, 2.6rem); font-weight: 800; letter-spacing: -0.01em; }
h2 { font-size: 1.35rem; font-weight: 600; }
.eyebrow { font: 700 0.75rem/1 var(--f-body); letter-spacing: 0.12em; text-transform: uppercase; color: var(--accent); }
.lead { color: var(--muted); margin: 0; max-width: 60ch; }
.panel { background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 22px; display: grid; gap: 14px; }
.row { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
label { font-weight: 700; }
input[type="text"], textarea {
  font: inherit; color: var(--ink); background: var(--paper); border: 2px solid var(--line); border-radius: 10px; padding: 10px 12px; width: 100%; box-sizing: border-box;
}
input[type="text"]:focus, textarea:focus { outline: none; border-color: var(--accent); }
button { font: 700 1rem/1 var(--f-body); border-radius: 10px; padding: 12px 18px; border: 2px solid transparent; cursor: pointer; color: var(--ink); background: transparent; }
button:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
.btn { background: var(--accent); color: var(--accent-ink); }
.btn:hover { filter: brightness(1.07); }
.btn-ghost { border-color: var(--line); background: var(--card); }
.btn-ghost:hover { border-color: var(--accent); }
button:disabled { opacity: 0.45; cursor: not-allowed; }
.sections { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 10px; }
.sec { text-align: left; border: 2px solid var(--line); background: var(--card); padding: 14px; border-radius: 12px; display: grid; gap: 4px; line-height: 1.3; }
.sec small { font-weight: 400; color: var(--muted); }
.sec[aria-pressed="true"] { border-color: var(--accent); background: var(--accent-soft); }
.levels { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 10px; }
@media (max-width: 520px) { .levels { grid-template-columns: 1fr; } }
.lvl { border: 2px solid var(--line); background: var(--card); padding: 14px; border-radius: 12px; text-align: left; display: grid; gap: 4px; line-height: 1.3; }
.lvl small { font-weight: 400; color: var(--muted); }
.lvl[aria-pressed="true"] { border-color: var(--accent); background: var(--accent-soft); }
.progress { display: flex; gap: 6px; }
.progress span { flex: 1; height: 8px; border-radius: 4px; background: var(--line); }
.progress span.ok { background: var(--good); }
.progress span.miss { background: var(--bad); }
.progress span.now { background: var(--accent); opacity: 0.55; }
.qhead { display: flex; justify-content: space-between; align-items: baseline; gap: 10px; flex-wrap: wrap; }
.qnum { font: 800 1.1rem var(--f-display); }
.qtag { font-size: 0.85rem; color: var(--muted); }
.qtext { font-size: 1.12rem; margin: 0; }
.m { font-family: var(--f-math); font-size: 1.12em; white-space: nowrap; }
.m i { font-style: italic; }
.frac { display: inline-flex; flex-direction: column; vertical-align: middle; text-align: center; font-family: var(--f-math); line-height: 1.1; margin: 0 2px; }
.frac > span:first-child { border-bottom: 1.5px solid currentColor; padding: 0 3px; }
.opts { display: grid; gap: 8px; }
.opt { text-align: left; border: 2px solid var(--line); background: var(--card); font-weight: 400; line-height: 1.4; padding: 12px 14px; }
.opt:hover:not(:disabled) { border-color: var(--accent); }
.opt.right { border-color: var(--good); background: var(--good-soft); }
.opt.wrong { border-color: var(--bad); background: var(--bad-soft); }
.answer-row { display: flex; gap: 10px; flex-wrap: wrap; }
.answer-row input { flex: 1 1 220px; width: auto; font-size: 1.15rem; font-family: var(--f-math); }
.tip { font-size: 0.9rem; color: var(--muted); margin: 0; }
.feedback { border-radius: 10px; padding: 12px 14px; margin: 0; }
.feedback.good { background: var(--good-soft); color: var(--good); font-weight: 700; }
.feedback.bad { background: var(--bad-soft); color: var(--bad); }
.feedback.hint { background: var(--hint-soft); color: var(--hint-ink); }
.solution { border-left: 4px solid var(--accent); padding: 4px 0 4px 14px; display: grid; gap: 4px; }
.solution p { margin: 0; }
.score { font: 800 clamp(3rem, 12vw, 4.5rem)/1 var(--f-display); font-variant-numeric: tabular-nums; }
.code { font: 700 1.05rem/1.4 ui-monospace, "Cascadia Mono", Consolas, monospace; background: var(--paper); border: 2px dashed var(--accent); border-radius: 10px; padding: 14px; word-break: break-word; user-select: all; }
.steps { margin: 0; padding-left: 1.3em; display: grid; gap: 4px; }
.foot { text-align: center; font-size: 0.9rem; color: var(--muted); }
.foot a { color: var(--muted); }
table { border-collapse: collapse; width: 100%; font-variant-numeric: tabular-nums; font-size: 0.95rem; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); white-space: nowrap; }
th { font-size: 0.8rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); }
.tablebox { overflow-x: auto; }
.pill { display: inline-block; padding: 2px 10px; border-radius: 999px; font-size: 0.8rem; font-weight: 700; }
.pill.ok { background: var(--good-soft); color: var(--good); }
.pill.no { background: var(--bad-soft); color: var(--bad); }
.stats { display: flex; flex-wrap: wrap; gap: 18px; }
.stats div { display: grid; }
.stats b { font: 800 1.6rem var(--f-display); font-variant-numeric: tabular-nums; }
.stats span { font-size: 0.85rem; color: var(--muted); }
@media (prefers-reduced-motion: no-preference) { .panel { animation: rise .25s ease-out; } @keyframes rise { from { transform: translateY(6px); } to { transform: none; } } }