:root {
    --bg: #07131c;
    --line: rgba(255, 255, 255, 0.12);
    --gold: #f0c85a;
    --gold-2: #ffe08a;
    --mint: #5ee6c3;
    --mint-2: #c8fff0;
    --violet: #b9a6ff;
    --sky: #7ecbff;
    --peach: #ffb38a;
    --coral: #ff7d8a;
    --lime: #d4f56e;
    --text: #f8f4ee;
    --muted: #c5d0dc;
    --ok: #7ef0b0;
    --bad: #ff9aa8;
}

* { box-sizing: border-box; }

html { margin: 0; background: var(--bg); }

body {
    margin: 0;
    min-height: 100vh;
    color: var(--text);
    font-family: "Outfit", sans-serif;
    background:
        radial-gradient(900px 480px at -10% -10%, rgba(185, 166, 255, 0.28), transparent 55%),
        radial-gradient(820px 460px at 110% 0%, rgba(126, 203, 255, 0.22), transparent 50%),
        radial-gradient(700px 380px at 80% 110%, rgba(255, 125, 138, 0.16), transparent 46%),
        linear-gradient(165deg, #10263a 0%, #07131c 42%, #123028 100%);
}

.serif { font-family: "Fraunces", serif; }

.app {
    display: grid;
    grid-template-columns: 250px minmax(0, 1fr);
    align-items: start;
    min-height: 100vh;
}

.ai-credit {
    grid-column: 1 / -1;
    margin: 0;
    padding: 6px 16px 12px;
    text-align: center;
    font-size: 0.7rem;
    letter-spacing: 0.02em;
    color: rgba(197, 208, 220, 0.42);
}

.top {
    grid-column: 1 / -1;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    padding: 14px 24px;
    border-bottom: 1px solid var(--line);
    background: linear-gradient(90deg, rgba(18, 48, 72, 0.96), rgba(28, 36, 70, 0.96));
}

.back {
    display: inline-block;
    margin-bottom: 4px;
    color: var(--sky);
    text-decoration: none;
    font-size: 0.86rem;
}

.back:hover { text-decoration: underline; }

.kicker {
    margin: 0;
    letter-spacing: 0.16em;
    text-transform: uppercase;
    font-size: 0.7rem;
    color: var(--gold);
}

.top h1 {
    margin: 2px 0 0;
    font-size: clamp(1.2rem, 3vw, 1.55rem);
    font-weight: 600;
}

.xp-wrap { min-width: min(220px, 100%); }

.xp-label {
    display: flex;
    justify-content: space-between;
    font-size: 0.8rem;
    color: var(--muted);
    margin-bottom: 6px;
}

.xp-bar {
    height: 9px;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.1);
    overflow: hidden;
}

.xp-fill {
    height: 100%;
    width: 0;
    background: linear-gradient(90deg, var(--violet), var(--sky), var(--mint), var(--gold));
    transition: width 0.35s ease;
}

.nav {
    display: flex;
    flex-direction: column;
    gap: 8px;
    padding: 18px 12px 32px;
    border-right: 1px solid var(--line);
    background: rgba(8, 20, 32, 0.35);
}

.nav button {
    text-align: left;
    border: 1px solid transparent;
    border-left-width: 4px;
    background: rgba(255, 255, 255, 0.04);
    color: var(--text);
    border-radius: 14px;
    padding: 11px 12px;
    cursor: pointer;
    font: inherit;
}

.nav button:nth-child(1) { border-left-color: var(--mint); }
.nav button:nth-child(2) { border-left-color: var(--sky); }
.nav button:nth-child(3) { border-left-color: var(--gold); }
.nav button:nth-child(4) { border-left-color: var(--peach); }
.nav button:nth-child(5) { border-left-color: var(--violet); }
.nav button:nth-child(6) { border-left-color: var(--coral); }

.nav button small {
    display: block;
    color: var(--muted);
    font-size: 0.74rem;
    margin-top: 3px;
}

.nav button.is-active {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.14);
    border-left-width: 4px;
}

.nav button.is-done::after {
    content: " ✓";
    color: var(--ok);
}

.stage {
    padding: 24px 32px 88px;
    min-width: 0;
}

.badge {
    display: inline-flex;
    padding: 5px 10px;
    border-radius: 999px;
    background: rgba(185, 166, 255, 0.18);
    color: var(--violet);
    font-size: 0.75rem;
}

.stage h2 {
    margin: 10px 0 8px;
    font-size: clamp(1.45rem, 4vw, 2.1rem);
    line-height: 1.15;
}

.lead, .muted { color: var(--muted); line-height: 1.55; }

.key {
    display: inline;
    color: #ffe7a3;
    font-weight: 700;
    padding: 0 0.18em;
    background: linear-gradient(transparent 62%, rgba(240, 200, 90, 0.38) 62%);
    border-radius: 3px;
    box-decoration-break: clone;
    -webkit-box-decoration-break: clone;
}

.key-mint {
    color: #b8ffe8;
    background: linear-gradient(transparent 62%, rgba(94, 230, 195, 0.32) 62%);
}

.key-coral {
    color: #ffd0d6;
    background: linear-gradient(transparent 62%, rgba(255, 125, 138, 0.32) 62%);
}

.grid-2 {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 14px;
    margin-top: 16px;
}

.card {
    background: rgba(10, 24, 38, 0.7);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 18px;
    padding: 16px 18px;
}

.card.mint { border-color: rgba(94, 230, 195, 0.35); background: rgba(20, 60, 52, 0.45); }
.card.sky { border-color: rgba(126, 203, 255, 0.4); background: rgba(16, 48, 78, 0.5); }
.card.gold { border-color: rgba(240, 200, 90, 0.4); background: rgba(62, 48, 18, 0.5); }
.card.peach { border-color: rgba(255, 179, 138, 0.4); background: rgba(72, 38, 28, 0.48); }
.card.violet { border-color: rgba(185, 166, 255, 0.4); background: rgba(46, 32, 78, 0.5); }

.card h3 {
    margin: 0 0 10px;
    font-size: 1.05rem;
}

.card.example {
    background: linear-gradient(180deg, #2f4a42 0%, #243832 100%);
    border: 1.5px solid #c9b06a;
    box-shadow: 0 8px 22px rgba(0, 0, 0, 0.22);
    color: #f3eee4;
}

.card.example .example-label {
    margin: 0 0 6px;
    display: inline-block;
    padding: 3px 8px;
    border-radius: 999px;
    background: rgba(201, 176, 106, 0.18);
    color: #e8d59a;
    font-size: 0.7rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.card.example h3 {
    color: #f0e2b8;
}

.card.example .step.is-on {
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(201, 176, 106, 0.28);
    color: #f3eee4;
}

.card.example .ghost {
    color: #e8d59a;
    border-color: rgba(201, 176, 106, 0.45);
    background: rgba(201, 176, 106, 0.1);
}

.formula {
    font-family: "Fraunces", serif;
    font-size: clamp(1.05rem, 3vw, 1.28rem);
    background: rgba(94, 230, 195, 0.1);
    border: 1px dashed rgba(94, 230, 195, 0.4);
    border-radius: 14px;
    padding: 12px 14px;
    margin: 10px 0;
    overflow-wrap: anywhere;
}

.chips { display: flex; flex-wrap: wrap; gap: 8px; }

.chip {
    display: inline-flex;
    align-items: center;
    padding: 7px 12px;
    border-radius: 999px;
    background: rgba(94, 230, 195, 0.14);
    border: 1px solid rgba(94, 230, 195, 0.3);
}

.chip.gold { background: rgba(240, 200, 90, 0.16); border-color: rgba(240, 200, 90, 0.35); }
.chip.sky { background: rgba(126, 203, 255, 0.16); border-color: rgba(126, 203, 255, 0.4); color: var(--sky); }
.chip.peach { background: rgba(255, 179, 138, 0.16); border-color: rgba(255, 179, 138, 0.4); color: var(--peach); }
.chip.violet { background: rgba(185, 166, 255, 0.16); border-color: rgba(185, 166, 255, 0.4); color: var(--violet); }

.steps { display: grid; gap: 8px; margin-bottom: 12px; }
.step {
    display: none;
    padding: 8px 10px;
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.05);
}
.step.is-on { display: block; }

.btn, .ghost {
    border: 0;
    cursor: pointer;
    font: inherit;
    border-radius: 12px;
    padding: 11px 14px;
    min-height: 44px;
}

.btn {
    background: linear-gradient(180deg, var(--gold-2), var(--gold));
    color: #241804;
    font-weight: 700;
}

.btn:disabled { opacity: 0.55; cursor: default; }

.ghost {
    background: rgba(126, 203, 255, 0.08);
    color: var(--sky);
    border: 1px solid rgba(126, 203, 255, 0.35);
}

.toolbar {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin: 8px 0 0;
}

.lab { margin-top: 16px; }

.calc-board {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
    margin: 12px 0;
}

.calc-col {
    border-radius: 16px;
    padding: 14px;
}

.calc-col.left {
    background: rgba(126, 203, 255, 0.1);
    border: 1px solid rgba(126, 203, 255, 0.35);
}

.calc-col.right {
    background: rgba(255, 179, 138, 0.1);
    border: 1px solid rgba(255, 179, 138, 0.35);
}

.calc-col h4 { margin: 0 0 8px; }
.calc-col .expr { color: var(--muted); margin: 0 0 10px; }
.calc-col ol {
    margin: 0;
    padding-left: 18px;
    display: grid;
    gap: 8px;
    line-height: 1.45;
}
.calc-result {
    margin-top: 12px;
    font-family: "Fraunces", serif;
    font-size: 1.5rem;
    color: var(--lime);
}

.verdict {
    padding: 12px 14px;
    border-radius: 12px;
    margin: 8px 0 0;
}
.verdict.ok {
    background: rgba(126, 240, 176, 0.12);
    border: 1px solid rgba(126, 240, 176, 0.35);
    color: var(--ok);
}
.verdict.bad {
    background: rgba(255, 154, 168, 0.12);
    border: 1px solid rgba(255, 154, 168, 0.35);
    color: var(--bad);
}

.quiz { display: grid; gap: 12px; margin-top: 20px; }
.quiz-head {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
}
.quiz-head h3 { margin: 0; }

.q {
    padding: 16px;
    border-radius: 16px;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(255, 255, 255, 0.07);
    border-left: 4px solid var(--sky);
}
.q:nth-child(3n) { border-left-color: var(--mint); }
.q:nth-child(3n+1) { border-left-color: var(--peach); }
.q:nth-child(3n+2) { border-left-color: var(--violet); }

.q label { display: block; margin-bottom: 10px; font-weight: 500; }

.q-tag,
.q-num {
    display: inline-block;
    margin-right: 8px;
    font-weight: 700;
}

.q-tag {
    padding: 2px 8px;
    border-radius: 999px;
    background: rgba(240, 200, 90, 0.16);
    color: var(--gold-2);
    font-size: 0.72rem;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    vertical-align: middle;
}

.q-num { color: var(--muted); }

.is-hidden { display: none !important; }

.exam-intro {
    padding: 22px 20px;
}

.exam-q {
    padding: 22px 20px;
    min-height: 260px;
}

.exam-q label {
    font-size: 1.18rem;
    line-height: 1.45;
}

.slide-meta {
    margin: 0 0 8px;
    color: var(--gold-2);
    letter-spacing: 0.08em;
    text-transform: uppercase;
    font-size: 0.78rem;
    font-weight: 700;
}

.slide-track {
    height: 8px;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.1);
    overflow: hidden;
    margin-bottom: 16px;
}

.slide-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--violet), var(--sky), var(--gold));
    transition: width 0.25s ease;
}

.quiz.exam.is-graded .q.is-ok,
.exam-q.is-ok {
    border-left-color: var(--ok);
    background: rgba(126, 240, 176, 0.08);
}

.quiz.exam.is-graded .q.is-bad,
.exam-q.is-bad {
    border-left-color: var(--bad);
    background: rgba(255, 154, 168, 0.08);
}

.exam-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 8px;
}

.exam-report { margin-top: 8px; }

.grade-score {
    font-family: "Fraunces", serif;
    font-size: clamp(2.2rem, 8vw, 3.2rem);
    margin: 8px 0 4px;
    line-height: 1;
}

.grade-score span {
    font-size: 0.45em;
    color: var(--muted);
}

.review-list {
    list-style: none;
    margin: 12px 0 0;
    padding: 0;
    display: grid;
    gap: 12px;
}

.review-list li {
    padding: 12px 14px;
    border-radius: 14px;
    background: rgba(0, 0, 0, 0.18);
}

.review-list p { margin: 6px 0 10px; color: var(--muted); }
.q-row {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    align-items: center;
}
.q input[type="text"] {
    flex: 1 1 220px;
    min-width: 0;
    max-width: 420px;
    border: 1px solid rgba(185, 166, 255, 0.35);
    background: rgba(0, 0, 0, 0.28);
    color: var(--text);
    border-radius: 12px;
    padding: 11px 12px;
    font: inherit;
    min-height: 44px;
}

.feedback { margin-top: 8px; font-size: 0.92rem; min-height: 1.2em; }
.feedback.ok { color: var(--ok); }
.feedback.bad { color: var(--bad); }

.choices { display: flex; gap: 8px; flex-wrap: wrap; }
.choices button {
    background: rgba(255, 255, 255, 0.06);
    color: var(--text);
    border: 1px solid rgba(255, 255, 255, 0.12);
    border-radius: 999px;
    padding: 10px 16px;
    min-height: 44px;
    cursor: pointer;
    font: inherit;
}

.dist-expr {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    align-items: center;
    justify-content: center;
    font-family: "Fraunces", serif;
    font-size: clamp(1.6rem, 5vw, 2.3rem);
    margin: 12px 0 16px;
    padding: 12px;
    border-radius: 16px;
    background: rgba(0, 0, 0, 0.18);
}

.dist-factor {
    display: inline-flex;
    min-width: 1.6em;
    justify-content: center;
    padding: 4px 10px;
    border-radius: 12px;
    background: var(--gold);
    color: #1c1408;
}

.dist-term {
    padding: 4px 10px;
    border-radius: 12px;
    border: 2px dashed rgba(255, 255, 255, 0.25);
}

.dist-term.is-on {
    border-style: solid;
    border-color: var(--mint);
    background: rgba(94, 230, 195, 0.16);
}

.dist-row {
    margin-top: 12px;
    padding: 12px 14px;
    border-radius: 14px;
    background: rgba(255, 255, 255, 0.05);
}

.dist-row.is-locked {
    opacity: 0.38;
    pointer-events: none;
}

.dist-op {
    font-size: 1.2rem;
    margin: 8px 0;
}

.dist-op span, .dist-op [data-dist-slot] {
    display: inline-block;
    min-width: 1.6em;
    padding: 2px 8px;
    border-radius: 8px;
    background: rgba(255, 255, 255, 0.08);
}

[data-dist-slot].is-filled {
    background: var(--lime);
    color: #1c1408;
    font-weight: 700;
}

.dist-result {
    margin-top: 14px;
    padding: 14px;
    border-radius: 14px;
    background: rgba(126, 240, 176, 0.14);
    border: 1px solid rgba(126, 240, 176, 0.4);
    font-size: 1.05rem;
}

.dist-result.is-hidden,
.cf-expr.is-hidden { display: none; }

.cf {
    display: inline-flex;
    align-items: baseline;
    padding: 1px 8px;
    margin: 0 1px;
    border-radius: 8px;
    background: var(--gold);
    color: #1c1408;
    font-weight: 700;
    box-shadow: 0 0 0 2px rgba(240, 200, 90, 0.28);
}

.cf-expr {
    font-family: "Fraunces", serif;
    font-size: clamp(1.35rem, 4.2vw, 2rem);
    text-align: center;
    line-height: 1.45;
    padding: 12px 10px;
    margin: 10px 0 0;
    border-radius: 16px;
    background: rgba(0, 0, 0, 0.18);
    overflow-wrap: anywhere;
}

.hint,
.note {
    position: relative;
    color: #f3e6b8;
    font-size: 0.95rem;
    line-height: 1.5;
    margin: 12px 0 0;
    padding: 12px 14px 12px 16px;
    border-radius: 12px;
    background: rgba(240, 200, 90, 0.1);
    border: 1px solid rgba(240, 200, 90, 0.28);
    border-left: 4px solid var(--gold);
}

.hint::before,
.note::before {
    content: "À retenir";
    display: block;
    margin-bottom: 4px;
    font-size: 0.7rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--gold-2);
    font-weight: 700;
}

.warn {
    position: relative;
    border-left: 4px solid var(--coral);
    padding: 12px 14px;
    border-radius: 0 12px 12px 0;
    background: rgba(255, 125, 138, 0.12);
    border: 1px solid rgba(255, 125, 138, 0.28);
    border-left-width: 4px;
    color: #ffd4da;
}

.warn::before {
    content: "Attention";
    display: block;
    margin-bottom: 4px;
    font-size: 0.7rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--coral);
    font-weight: 700;
}

footer.nav-mod {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    margin-top: 28px;
    padding-top: 18px;
    padding-bottom: calc(16px + env(safe-area-inset-bottom));
    border-top: 1px solid var(--line);
}

@media (max-width: 900px) {
    .app { grid-template-columns: 1fr; }
    .nav {
        flex-direction: row;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        border-right: 0;
        border-bottom: 1px solid var(--line);
        padding: 10px 12px;
        gap: 6px;
    }
    .nav button {
        flex: 0 0 auto;
        min-width: max-content;
        padding: 10px 12px;
        font-size: 0.88rem;
    }
    .nav button small { display: none; }
    .top {
        flex-direction: column;
        align-items: stretch;
        padding: 12px 14px;
    }
    .grid-2, .calc-board { grid-template-columns: 1fr; }
    .stage { padding: 16px 14px 72px; }
}

@media (max-width: 640px) {
    .q-row, .toolbar, footer.nav-mod, .quiz-head, .exam-actions {
        flex-direction: column;
        align-items: stretch;
    }
    footer.nav-mod { flex-direction: column-reverse; }
    .q input[type="text"] {
        max-width: none;
        width: 100%;
    }
    .choices button { flex: 1 1 calc(50% - 8px); }
    .formula { font-size: 1.02rem; }
}