:root {
    /* ── Couleurs principales ── */
    --c-primary: #1a3a6b;
    --c-primary-lt: #2451a0;
    --c-accent: #e67e22;

    /* ── Surfaces & texte ── */
    --c-bg: #f4f7fb;
    --c-white: #ffffff;
    --c-text: #1c2a3a;
    --c-muted: #6b7a8d;
    --c-border: #dde3ed;

    /* ── Rayon global ── */
    --c-radius: 10px;

    /* ── Boîtes sémantiques ── */
    --c-tip-bg: #e6f9f0;
    --c-tip-border: #2ecc71;
    --c-tip-icon: #27ae60;
    --c-warn-bg: #fff8e1;
    --c-warn-border: #f1c40f;
    --c-warn-icon: #d68910;
    --c-danger-bg: #fdecea;
    --c-danger-border: #e74c3c;
    --c-danger-icon: #c0392b;
    --c-def-bg: #f0faff;
    --c-def-border: #17a2b8;
    --c-def-icon: #138496;
    --c-theorem-bg: #fffdf0;
    --c-theorem-border: #f0a500;
    --c-theorem-icon: #c87c00;
    --c-prop-bg: #f5f0ff;
    --c-prop-border: #7c3aed;
    --c-prop-icon: #6d28d9;
    --c-lemme-bg: #f0fdf4;
    --c-lemme-border: #16a34a;
    --c-lemme-icon: #15803d;

    /* ── Labels décorratifs ── */
    --c-ex-icon: #16a34a;
    --c-ex-line: #bbf7d0;
    --c-app-icon: #2563eb;
    --c-app-line: #bfdbfe;
    --c-pre-icon: #059669;
    --c-pre-line: #a7f3d0;
    --c-obj-icon: #be185d;
    --c-obj-line: #fbcfe8;
    --c-hist-icon: #78350f;
    --c-hist-line: #fde68a;
    --c-extra-icon: #4b5563;
    --c-extra-line: #e5e7eb;
    --c-sum-icon: #1e40af;
    --c-sum-line: #bfdbfe;
    --c-voc-icon: #6d28d9;
    --c-voc-line: #ddd6fe;
}

/* ============================================================
   BASE
   ============================================================ */
*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    color: var(--c-text);
    background: var(--c-bg);
    margin: 0;
    min-height: 100vh;
}

a {
    text-decoration: none;
}

.contenu-cours {
    font-size: .97rem;
    line-height: 1.8;
    color: var(--c-text);
}

/* ============================================================
   TYPOGRAPHIE — Titres
   ============================================================ */

/* H2 — Titre de chapitre */
.contenu-cours h2 {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    font-size: 1.75rem;
    font-weight: 800;
    color: var(--c-primary);
    padding: 0.8rem 1.2rem;
    border-left: 5px solid var(--c-accent);
    border-radius: 0 8px 8px 0;
    margin: 3.5rem 0 1.5rem;
    position: relative;
}

.contenu-cours h2::before {
    font-family: "bootstrap-icons";
    content: '\F2DA';
    color: var(--c-accent);
    font-size: 1.3rem;
    flex-shrink: 0;
}

/* H3 — Sous-titre de section */
.contenu-cours h3 {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--c-primary-lt);
    margin: 2.5rem 0 1rem;
    padding-bottom: 0.5rem;
    position: relative;
}

.contenu-cours h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 3px;
    background: var(--c-primary-lt);
    border-radius: 2px;
}

/* H4 — Points clés */
.contenu-cours h4 {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--c-accent);
    margin: 1.8rem 0 0.8rem;
    position: relative;
}

.contenu-cours h4::before {
    font-family: "bootstrap-icons";
    content: '\F3FF';
    font-size: 1rem;
    opacity: .8;
    flex-shrink: 0;
}

/* H5 — Remarques */
.contenu-cours h5 {
    font-size: 1rem;
    font-weight: 600;
    font-style: italic;
    color: var(--c-muted);
    margin: 1.2rem 0 0.6rem;
    padding-left: 1rem;
    border-left: 2px solid var(--c-border);
}

/* H6 — Micro-titre (Principe, Implémentation…) */
.contenu-cours h6 {
    font-size: .72rem;
    font-weight: 700;
    color: var(--c-pre-icon);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin: 1.8rem 0 .4rem;
    display: flex;
    align-items: center;
    gap: .6rem;
}

.contenu-cours h6::after {
    content: '';
    flex: 0 1 30px;
    height: 2px;
    background: var(--c-pre-icon);
    border-radius: 2px;
}

/* ── Paragraphes & liens ── */
.contenu-cours p {
    margin-bottom: 1rem;
}

.contenu-cours a {
    color: var(--c-primary-lt);
    text-decoration: underline;
    text-underline-offset: 2px;
    transition: color .2s;
}

.contenu-cours a:hover {
    color: var(--c-accent);
}

.contenu-cours :not(pre)>code {
    font-family: 'Fira Code', monospace;
    font-size: .85em;
    background: #f0f4ff;
    color: var(--c-danger-icon);
    padding: .1em .4em;
    border-radius: 4px;
    border: 1px solid var(--c-border);
}

.contenu-cours pre {
    border-radius: var(--c-radius);
    margin: 1.25rem 0;
    font-size: .88rem;
    overflow-x: auto;
    box-shadow: 0 4px 16px rgba(0, 0, 0, .18);
}

/* Bouton copier */
.contenu-cours .code-block-wrapper {
    position: relative;
}

.contenu-cours .code-copy-btn {
    position: absolute;
    top: .5rem;
    right: .5rem;
    background: rgba(255, 255, 255, .12);
    border: 1px solid rgba(255, 255, 255, .2);
    color: rgba(255, 255, 255, .7);
    font-size: .72rem;
    padding: .2rem .55rem;
    border-radius: 4px;
    cursor: pointer;
    transition: background .2s, color .2s;
}

.contenu-cours .code-copy-btn:hover {
    background: rgba(255, 255, 255, .25);
    color: #fff;
}

/* ============================================================
   LISTES
   ============================================================ */
.contenu-cours ul,
.contenu-cours ol {
    padding-left: 1.5rem;
    margin-bottom: 1rem;
}

.contenu-cours li {
    margin-bottom: .35rem;
}

.contenu-cours ul li::marker {
    color: var(--c-accent);
}

/* ============================================================
   TABLEAU
   ============================================================ */
.contenu-cours table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.25rem 0;
    font-size: .9rem;
    border-radius: var(--c-radius);
    overflow: hidden;
    box-shadow: 0 1px 6px rgba(0, 0, 0, .07);
}

.contenu-cours thead th {
    background: var(--c-primary);
    color: var(--c-white);
    padding: .65rem 1rem;
    font-weight: 600;
    text-align: left;
}

.contenu-cours tbody tr:nth-child(even) {
    background: var(--c-bg);
}

.contenu-cours tbody tr:hover {
    background: #e8eef8;
    transition: background .15s;
}

.contenu-cours tbody td {
    padding: .6rem 1rem;
    border-bottom: 1px solid var(--c-border);
}

/* ============================================================
   LABELS DÉCORATIFS (label-*)
   — Base commune + couleurs individuelles
   ============================================================ */
.contenu-cours .label-exemple,
.contenu-cours .label-application,
.contenu-cours .label-prerequis,
.contenu-cours .label-objectif,
.contenu-cours .label-culture,
.contenu-cours .label-resume,
.contenu-cours .label-complement,
.contenu-cours .label-vocabulaire {
    display: flex;
    align-items: center;
    gap: .5rem;
    font-size: .72rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 1.1px;
    margin: 2rem 0 .4rem;
}

/* Ligne décorative (::after) */
.contenu-cours .label-exemple::after,
.contenu-cours .label-application::after,
.contenu-cours .label-prerequis::after,
.contenu-cours .label-objectif::after,
.contenu-cours .label-culture::after,
.contenu-cours .label-resume::after,
.contenu-cours .label-complement::after,
.contenu-cours .label-vocabulaire::after {
    content: '';
    flex: 1;
    height: 1px;
}

/* Couleurs individuelles */
.contenu-cours .label-exemple {
    color: var(--c-ex-icon);
}

.contenu-cours .label-exemple::after {
    background: var(--c-ex-line);
}

.contenu-cours .label-application {
    color: var(--c-app-icon);
}

.contenu-cours .label-application::after {
    background: var(--c-app-line);
}

.contenu-cours .label-prerequis {
    color: var(--c-pre-icon);
}

.contenu-cours .label-prerequis::after {
    background: var(--c-pre-line);
}

.contenu-cours .label-objectif {
    color: var(--c-obj-icon);
}

.contenu-cours .label-objectif::after {
    background: var(--c-obj-line);
}

.contenu-cours .label-culture {
    color: var(--c-hist-icon);
}

.contenu-cours .label-culture::after {
    background: var(--c-hist-line);
}

.contenu-cours .label-resume {
    color: var(--c-sum-icon);
}

.contenu-cours .label-resume::after {
    background: var(--c-sum-line);
}

.contenu-cours .label-complement {
    color: var(--c-extra-icon);
}

.contenu-cours .label-complement::after {
    background: var(--c-extra-line);
}

.contenu-cours .label-vocabulaire {
    color: var(--c-voc-icon);
}

.contenu-cours .label-vocabulaire::after {
    background: var(--c-voc-line);
}

/* ============================================================
   BOÎTES CALLOUT (box-*)
   — Base commune + variantes
   ============================================================ */
.contenu-cours .box-tip,
.contenu-cours .box-warning,
.contenu-cours .box-danger,
.contenu-cours .box-definition,
.contenu-cours .box-theorem,
.contenu-cours .box-proposition,
.contenu-cours .box-lemme {
    border-radius: var(--c-radius);
    padding: 1rem 1.25rem 1rem 3.5rem;
    margin: 1.25rem 0;
    position: relative;
    font-size: .93rem;
}

/* Couleurs & bordures */
.contenu-cours .box-tip {
    background: var(--c-tip-bg);
    border-left: 4px solid var(--c-tip-border);
}

.contenu-cours .box-warning {
    background: var(--c-warn-bg);
    border-left: 4px solid var(--c-warn-border);
}

.contenu-cours .box-danger {
    background: var(--c-danger-bg);
    border-left: 4px solid var(--c-danger-border);
}

.contenu-cours .box-definition {
    background: var(--c-def-bg);
    border-left: 4px solid var(--c-def-border);
}

.contenu-cours .box-theorem {
    background: var(--c-theorem-bg);
    border-left: 4px solid var(--c-theorem-border);
}

.contenu-cours .box-proposition {
    background: var(--c-prop-bg);
    border-left: 4px solid var(--c-prop-border);
}

.contenu-cours .box-lemme {
    background: var(--c-lemme-bg);
    border-left: 4px solid var(--c-lemme-border);
}

/* Icône Bootstrap Icons positionnée à gauche */
.contenu-cours [class^="box-"]::before {
    font-family: "bootstrap-icons";
    font-size: 1.25rem;
    position: absolute;
    left: 1rem;
    top: 1rem;
    line-height: 1;
}

.contenu-cours .box-tip::before {
    content: '\F44D';
    color: var(--c-tip-icon);
}

.contenu-cours .box-warning::before {
    content: '\F33B';
    color: var(--c-warn-icon);
}

.contenu-cours .box-danger::before {
    content: '\F337';
    color: var(--c-danger-icon);
}

.contenu-cours .box-definition::before {
    content: '\F192';
    color: var(--c-def-icon);
}

.contenu-cours .box-theorem::before {
    content: '\F477';
    color: var(--c-theorem-icon);
}

.contenu-cours .box-proposition::before {
    content: '\F4EE';
    color: var(--c-prop-icon);
}

.contenu-cours .box-lemme::before {
    content: '\F466';
    color: var(--c-lemme-icon);
}

/* Titre de boîte */
.contenu-cours .box-title {
    font-weight: 700;
    font-size: .85rem;
    text-transform: uppercase;
    letter-spacing: .5px;
    margin-bottom: .4rem;
    display: block;
}

.contenu-cours .box-tip .box-title {
    color: var(--c-tip-icon);
}

.contenu-cours .box-warning .box-title {
    color: var(--c-warn-icon);
}

.contenu-cours .box-danger .box-title {
    color: var(--c-danger-icon);
}

.contenu-cours .box-definition .box-title {
    color: var(--c-def-icon);
}

.contenu-cours .box-theorem .box-title {
    color: var(--c-theorem-icon);
}

.contenu-cours .box-proposition .box-title {
    color: var(--c-prop-icon);
}

.contenu-cours .box-lemme .box-title {
    color: var(--c-lemme-icon);
}

/* ============================================================
   BOÎTE SYNTAXE (style éditeur de code)
   ============================================================ */
.contenu-cours .box-syntax {
    margin: 1.25rem 0;
    border-radius: var(--c-radius);
    overflow: hidden;
    border: 1px solid #2a2a3d;
    box-shadow: 0 4px 18px rgba(0, 0, 0, .13);
}

.contenu-cours .box-syntax::before {
    content: none;
}

.contenu-cours .box-syntax-header {
    background: #1e1e2e;
    padding: .5rem 1rem;
    display: flex;
    align-items: center;
    gap: .75rem;
}

.contenu-cours .box-syntax-dots {
    display: flex;
    gap: .35rem;
    flex-shrink: 0;
}

.contenu-cours .box-syntax-dots span {
    width: 11px;
    height: 11px;
    border-radius: 50%;
    display: inline-block;
}

.contenu-cours .box-syntax-dots span:nth-child(1) {
    background: #ff5f57;
}

.contenu-cours .box-syntax-dots span:nth-child(2) {
    background: #febc2e;
}

.contenu-cours .box-syntax-dots span:nth-child(3) {
    background: #28c840;
}

.contenu-cours .box-syntax .box-title {
    color: #8892a4;
    font-size: .7rem;
    letter-spacing: .9px;
    font-weight: 600;
    text-transform: uppercase;
    margin: 0;
}

.contenu-cours .box-syntax .box-lang {
    margin-left: auto;
    font-size: .68rem;
    font-weight: 600;
    color: #6c86ad;
    letter-spacing: .5px;
    font-family: 'Fira Code', monospace;
}

.contenu-cours .box-syntax pre {
    margin: 0;
    padding: 1.1rem 1.4rem;
    background: #13131e;
    border-radius: 0;
    font-size: .875rem;
    box-shadow: none;
}

.contenu-cours .box-syntax pre code {
    background: transparent;
    font-family: 'Fira Code', monospace;
}

/* ============================================================
   BOÎTE SORTIE (terminal)
   ============================================================ */
.contenu-cours .box-sortie {
    margin: 0 0 1.25rem;
    border-radius: 0 0 var(--c-radius) var(--c-radius);
    overflow: hidden;
    border: 1px solid #166534;
    border-top: 1px dashed #1e6b3a;
}

.contenu-cours .box-sortie::before {
    content: none;
}

.contenu-cours .box-sortie-header {
    background: #071a0d;
    padding: .3rem 1rem;
    display: flex;
    align-items: center;
    gap: .5rem;
    color: #4ade80;
    font-size: .67rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: .8px;
    font-family: 'Fira Code', monospace;
}

.contenu-cours .box-sortie-header i {
    font-size: .82rem;
}

.contenu-cours .box-sortie pre {
    margin: 0;
    padding: .7rem 1.25rem;
    background: #030d05;
    color: #86efac;
    font-family: 'Fira Code', monospace;
    font-size: .82rem;
    border-radius: 0;
    box-shadow: none;
}

/* ============================================================
   BLOCS ENTRÉE / SORTIE (io-example)
   ============================================================ */
/* ── Conteneur principal ── */
.io-example {
    border: 1px solid #1e2d40;
    border-radius: var(--c-radius);
    overflow: hidden;
    margin: 1.5rem 0;
    box-shadow: 0 4px 18px rgba(0, 0, 0, .12);
}

/* ── Barre de titre ── */
.io-example-header {
    background: linear-gradient(90deg, #182030 0%, #1e2d40 100%);
    color: var(--c-white);
    font-size: .72rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: .7px;
    padding: .45rem 1rem;
    display: flex;
    align-items: center;
    gap: .5rem;
}

.io-example-header::before {
    content: '\F4FB';
    font-family: "bootstrap-icons";
    font-size: .85rem;
    color: var(--c-accent);
    flex-shrink: 0;
}

/* ── Corps : flexbox → 1 ou 2 blocs côte à côte ── */
.io-example-body {
    display: flex;
    flex-wrap: wrap;
    min-height: 70px;
}

/* Chaque bloc (input ou output) prend la place disponible
   min-width garantit le retour à la ligne sur petits écrans */
.io-block {
    flex: 1;
    min-width: 200px;
    padding: .85rem 1.1rem;
}

/* Séparateur vertical entre blocs adjacents */
.io-block+.io-block {
    border-left: 1px solid rgba(255, 255, 255, .07);
}

/* ── Couleurs de fond par type ── */
.io-input {
    background: #1b2840;
}

.io-output {
    background: #121e14;
}

/* ── Label (ENTRÉE / SORTIE) ── */
.io-label {
    font-size: .68rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: .6px;
    margin-bottom: .5rem;
    display: flex;
    align-items: center;
    gap: .35rem;
    opacity: .75;
}

.io-input .io-label {
    color: #93c5fd;
}

.io-output .io-label {
    color: #86efac;
}

.io-input .io-label i {
    color: #60a5fa;
}

.io-output .io-label i {
    color: #4ade80;
}

/* ── Contenu pre dans les blocs ── */
.io-block pre {
    margin: 0;
    padding: 0;
    background: transparent !important;
    box-shadow: none !important;
    border-radius: 0;
    font-family: 'Fira Code', monospace;
    font-size: .88rem;
    line-height: 1.7;
    color: #e2e8f0;
    white-space: pre-wrap;
    word-break: break-word;
}

/* ── Zone d'explication ── */
.io-explanation {
    background: #f4f8fc;
    border-top: 1px solid #d0daea;
    padding: .6rem 1.1rem;
    font-size: .82rem;
    color: var(--c-muted);
    line-height: 1.65;
}

.io-explanation strong {
    color: var(--c-text);
}

/* Contraintes */
.io-constraints {
    background: var(--c-theorem-bg);
    border: 1px solid var(--c-theorem-border);
    border-left: 4px solid var(--c-theorem-border);
    border-radius: var(--c-radius);
    padding: .75rem 1rem .75rem 1.2rem;
    margin: 1rem 0;
    font-size: .85rem;
}

.io-constraints-title {
    font-size: .75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: .5px;
    color: var(--c-theorem-icon);
    margin-bottom: .4rem;
    display: flex;
    align-items: center;
    gap: .35rem;
}

.io-constraints ul {
    margin: 0;
    padding-left: 1.2rem;
    color: var(--c-text);
}

.io-constraints li {
    margin-bottom: .2rem;
}

/* ============================================================
   ONGLETS LANGAGE (lang-tabs)
   ============================================================ */
.lang-tabs-wrap {
    margin: 1.5rem 0;
    border: 1px solid var(--c-border);
    border-radius: var(--c-radius);
    overflow: hidden;
    box-shadow: 0 4px 16px rgba(0, 0, 0, .10);
}

.lang-tabs-header {
    display: flex;
    flex-wrap: wrap;
    gap: .25rem;
    background: #1a2535;
    border-bottom: 2px solid #0d1421;
    padding: .35rem .5rem;
    overflow-x: auto;
    scrollbar-width: none;
}

.lang-tabs-header::-webkit-scrollbar {
    display: none;
}

.lang-tab-btn {
    display: inline-flex;
    align-items: center;
    gap: .4rem;
    padding: .4rem .85rem;
    font-size: .78rem;
    font-weight: 600;
    color: rgba(255, 255, 255, .5);
    background: transparent;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    white-space: nowrap;
    transition: background .15s, color .15s;
    font-family: 'Inter', sans-serif;
}

.lang-tab-btn:hover {
    color: rgba(255, 255, 255, .85);
    background: rgba(255, 255, 255, .06);
}

.lang-tab-btn.active {
    color: #fff;
    background: rgba(255, 255, 255, .12);
}

/* Points colorés par langage */
.lang-tab-btn .lang-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    flex-shrink: 0;
}

.dot-c {
    background: #4fa3e0;
}

.dot-python {
    background: #f7c948;
}

.dot-js {
    background: #f0db4f;
}

.dot-php {
    background: #8892be;
}

.dot-java {
    background: #f89820;
}

.dot-cpp {
    background: #659ad2;
}

.dot-bash {
    background: #4eaa25;
}

.dot-sql {
    background: #e38c00;
}

.lang-tab-panel {
    display: none;
}

.lang-tab-panel.active {
    display: block;
}

.lang-tabs-wrap .lang-tab-panel pre {
    margin: 0;
    border-radius: 0;
    box-shadow: none;
    font-size: .86rem;
}

/* ============================================================
   EXERCICES & SOLUTIONS
   ============================================================ */
.contenu-cours .exercise-card {
    --ex-accent: #2563eb;
    --ex-accent-soft: #dbeafe;
    --ex-accent-dark: #1d4ed8;
    --sol-accent: #16a34a;
    --sol-accent-soft: #dcfce7;
    margin: 1.5rem 0;
    border: 1px solid var(--c-border);
    border-radius: calc(var(--c-radius) + 4px);
    overflow: hidden;
    background: var(--c-white);
    box-shadow: 0 8px 24px rgba(15, 23, 42, .08);
    transition: box-shadow .2s;
}

.contenu-cours .exercise-card:hover {
    box-shadow: 0 12px 32px rgba(15, 23, 42, .12);
}

.contenu-cours .exercise-card+.exercise-card {
    margin-top: 1.75rem;
}

.contenu-cours .exercise-header {
    background: linear-gradient(135deg, #eff6ff 0%, var(--c-white) 100%);
    border-bottom: 1px solid var(--c-border);
    padding: 1rem 1.2rem;
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 1rem;
}

.contenu-cours .exercise-kicker {
    display: inline-flex;
    align-items: center;
    gap: .45rem;
    font-size: .72rem;
    font-weight: 800;
    letter-spacing: .8px;
    text-transform: uppercase;
    color: var(--ex-accent-dark);
    background: var(--ex-accent-soft);
    border: 1px solid #bfdbfe;
    border-radius: 999px;
    padding: .2rem .7rem;
    margin-bottom: .55rem;
}

.contenu-cours .exercise-title {
    font-size: 1.05rem;
    line-height: 1.4;
    font-weight: 800;
    color: var(--c-primary);
    margin: 0;
}

.contenu-cours .exercise-meta {
    display: flex;
    flex-wrap: wrap;
    gap: .45rem;
    align-items: center;
    justify-content: flex-end;
    min-width: 160px;
}

.contenu-cours .exercise-badge {
    display: inline-flex;
    align-items: center;
    gap: .3rem;
    font-size: .72rem;
    font-weight: 700;
    color: var(--c-primary-lt);
    background: #f8fafc;
    border: 1px solid var(--c-border);
    border-radius: 999px;
    padding: .2rem .65rem;
    white-space: nowrap;
}

.contenu-cours .exercise-body {
    padding: 1.15rem 1.2rem 1.25rem;
}

.contenu-cours .exercise-statement {
    color: var(--c-text);
}

.contenu-cours .exercise-statement> :last-child {
    margin-bottom: 0;
}

.contenu-cours .exercise-actions {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: .75rem;
    margin-top: 1rem;
    padding-top: .9rem;
    border-top: 1px dashed var(--c-border);
}

.contenu-cours .btn-solution-toggle {
    appearance: none;
    border: none;
    background: linear-gradient(135deg, var(--sol-accent) 0%, #15803d 100%);
    color: var(--c-white);
    border-radius: 999px;
    padding: .55rem 1rem;
    font-size: .82rem;
    font-weight: 700;
    display: inline-flex;
    align-items: center;
    gap: .45rem;
    cursor: pointer;
    box-shadow: 0 4px 14px rgba(22, 163, 74, .22);
    transition: transform .18s ease, box-shadow .18s ease, filter .18s ease;
}

.contenu-cours .btn-solution-toggle:hover {
    transform: translateY(-2px);
    filter: brightness(1.05);
    box-shadow: 0 8px 20px rgba(22, 163, 74, .32);
}

.contenu-cours .btn-solution-toggle .label-hide {
    display: none;
}

.contenu-cours .btn-solution-toggle[aria-expanded="true"] .label-show {
    display: none;
}

.contenu-cours .btn-solution-toggle[aria-expanded="true"] .label-hide {
    display: inline;
}

.contenu-cours .solution-panel {
    display: none;
    border-top: 1px solid var(--c-border);
    background: linear-gradient(180deg, #f7fff8 0%, var(--c-white) 100%);
}

.contenu-cours .solution-panel.is-open {
    display: block;
}

.contenu-cours .solution-header {
    display: flex;
    align-items: center;
    gap: .55rem;
    padding: .9rem 1.2rem;
    background: var(--sol-accent-soft);
    border-bottom: 1px solid #bbf7d0;
    color: #166534;
    font-size: .78rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: .8px;
}

.contenu-cours .solution-body {
    padding: 1rem 1.2rem 1.2rem;
}

.contenu-cours .solution-body> :last-child {
    margin-bottom: 0;
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 575px) {
    .io-example-body {
        grid-template-columns: 1fr;
    }

    .io-block+.io-block {
        border-left: none;
        border-top: 1px solid var(--c-border);
    }

    .contenu-cours .exercise-header {
        flex-direction: column;
    }

    .contenu-cours .exercise-meta {
        min-width: unset;
        justify-content: flex-start;
    }
}

@media (max-width: 991px) {
    .course-article {
        padding: 1.5rem 1.25rem;
        margin: 1rem;
        border-radius: var(--c-radius);
    }
}

/* ============================================================
   PROBLÈME INTERACTIF (prob-*)
   ============================================================ */

/* ── En-tête du problème ── */
.prob-header {
    background: linear-gradient(135deg, #0f2547 0%, var(--c-primary) 60%, #1e4080 100%);
    border-radius: var(--c-radius);
    padding: 2rem 2.5rem;
    color: #fff;
    margin-bottom: 1.75rem;
    position: relative;
    overflow: hidden;
}

.prob-header::before {
    content: '';
    position: absolute;
    top: -50px;
    right: -50px;
    width: 220px;
    height: 220px;
    border-radius: 50%;
    background: rgba(230, 126, 34, .1);
    pointer-events: none;
}

.prob-header::after {
    content: '';
    position: absolute;
    bottom: -70px;
    left: 35%;
    width: 300px;
    height: 300px;
    border-radius: 50%;
    background: rgba(255, 255, 255, .04);
    pointer-events: none;
}

.prob-meta {
    display: flex;
    flex-wrap: wrap;
    gap: .5rem;
    margin-bottom: 1rem;
    position: relative;
}

.prob-badge {
    display: inline-flex;
    align-items: center;
    gap: .3rem;
    font-size: .72rem;
    font-weight: 700;
    padding: .25rem .75rem;
    border-radius: 999px;
    text-transform: uppercase;
    letter-spacing: .6px;
}

.prob-badge-topic {
    background: rgba(255, 255, 255, .15);
    color: rgba(255, 255, 255, .92);
    border: 1px solid rgba(255, 255, 255, .2);
}

.prob-badge-easy {
    background: #dcfce7;
    color: #166534;
    border: 1px solid #86efac;
}

.prob-badge-medium {
    background: #fff8e1;
    color: #92400e;
    border: 1px solid #fcd34d;
}

.prob-badge-hard {
    background: #fdecea;
    color: #991b1b;
    border: 1px solid #fca5a5;
}

.prob-title {
    font-size: 1.8rem;
    font-weight: 800;
    color: #fff;
    margin: 0 0 .75rem;
    line-height: 1.25;
    position: relative;
}

.prob-desc {
    color: rgba(255, 255, 255, .8);
    font-size: .95rem;
    line-height: 1.75;
    margin-bottom: 1.25rem;
    max-width: 680px;
    position: relative;
}

.prob-objective {
    display: inline-flex;
    align-items: flex-start;
    gap: .6rem;
    background: rgba(230, 126, 34, .18);
    border: 1px solid rgba(230, 126, 34, .35);
    border-radius: 8px;
    padding: .6rem 1rem;
    font-size: .88rem;
    color: #fbd38d;
    line-height: 1.55;
    position: relative;
}

.prob-objective i {
    font-size: 1rem;
    flex-shrink: 0;
    margin-top: .1rem;
}

.prob-stats {
    display: flex;
    flex-wrap: wrap;
    gap: 1.5rem;
    margin-top: 1.5rem;
    padding-top: 1.25rem;
    border-top: 1px solid rgba(255, 255, 255, .12);
    position: relative;
}

.prob-stat-item {
    display: flex;
    align-items: center;
    gap: .45rem;
    font-size: .82rem;
    color: rgba(255, 255, 255, .65);
}

.prob-stat-item i {
    color: var(--c-accent);
    font-size: .95rem;
}

.prob-stat-item strong {
    color: #fff;
}

/* ── Parties (accordion) ── */
.prob-part {
    border: 1px solid var(--c-border);
    border-radius: calc(var(--c-radius) + 2px);
    overflow: hidden;
    margin-bottom: 1.25rem;
    background: var(--c-white);
    box-shadow: 0 2px 10px rgba(0, 0, 0, .05);
    transition: box-shadow .2s;
}

.prob-part:hover {
    box-shadow: 0 4px 18px rgba(0, 0, 0, .09);
}

.prob-part-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: linear-gradient(90deg, #f0f5ff 0%, var(--c-white) 100%);
    border-bottom: 1px solid var(--c-border);
}

.prob-part-num {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--c-primary);
    color: #fff;
    font-size: .78rem;
    font-weight: 800;
    flex-shrink: 0;
    letter-spacing: .2px;
}

.prob-part-title {
    flex: 1;
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--c-primary);
    margin: 0;
}

.prob-part-meta {
    font-size: .75rem;
    color: var(--c-muted);
    display: flex;
    align-items: center;
    gap: .35rem;
    flex-shrink: 0;
}

.prob-part-body {
    padding: 1.25rem 1.25rem 1rem;
}

.prob-part-desc {
    color: var(--c-muted);
    font-size: .9rem;
    line-height: 1.75;
    margin-bottom: 1.25rem;
    padding-bottom: 1rem;
    border-bottom: 1px dashed var(--c-border);
}

/* ── Questions ── */
.prob-question {
    background: #fafbfd;
    border: 1px solid var(--c-border);
    border-radius: var(--c-radius);
    margin-bottom: 1rem;
    overflow: hidden;
}

.prob-question:last-child {
    margin-bottom: 0;
}

.prob-question-header {
    display: grid;
    grid-template-columns: auto 1fr;
    align-items: start;
    gap: .25rem 1rem;
    padding: 1rem 1.2rem;
}

.prob-question-num {
    grid-column: 1;
    grid-row: 1;
}

.prob-question-header>*:not(.prob-question-num) {
    grid-column: 2;
}

.prob-question-header p {
    margin: 0;
}

.prob-question-num {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 28px;
    height: 28px;
    border-radius: 6px;
    background: var(--c-primary-lt);
    color: #fff;
    font-size: .72rem;
    font-weight: 800;
    flex-shrink: 0;
    margin-top: .15rem;
    padding: 0 .35rem;
}

.prob-question-statement {
    margin: 0;
    font-size: .93rem;
    color: var(--c-text);
    line-height: 1.75;
}

.prob-question-example {
    padding: 0 1.2rem .25rem;
}

.prob-question-actions {
    display: flex;
    align-items: center;
    gap: .75rem;
    padding: .75rem 1.2rem;
    border-top: 1px dashed var(--c-border);
    background: var(--c-white);
}

/* Bouton "Voir la solution" */
.btn-prob-sol {
    appearance: none;
    border: none;
    background: linear-gradient(135deg, var(--c-primary-lt) 0%, var(--c-primary) 100%);
    color: #fff;
    border-radius: 999px;
    padding: .45rem .95rem;
    font-size: .8rem;
    font-weight: 700;
    display: inline-flex;
    align-items: center;
    gap: .4rem;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(36, 81, 160, .22);
    transition: transform .15s ease, box-shadow .15s ease, filter .15s ease;
    font-family: 'Inter', sans-serif;
}

.btn-prob-sol:hover {
    transform: translateY(-1px);
    filter: brightness(1.1);
    box-shadow: 0 6px 16px rgba(36, 81, 160, .32);
}

.btn-prob-sol .label-hide {
    display: none;
}

.btn-prob-sol[aria-expanded="true"] .label-show {
    display: none;
}

.btn-prob-sol[aria-expanded="true"] .label-hide {
    display: inline;
}

/* Panneau solution */
.prob-sol-panel {
    display: none;
}

.prob-sol-panel.is-open {
    display: block;
}

.prob-sol-header {
    display: flex;
    align-items: center;
    gap: .5rem;
    padding: .65rem 1.2rem;
    background: #f0fdf4;
    border-top: 1px solid var(--c-border);
    border-bottom: 1px solid #bbf7d0;
    font-size: .72rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: .7px;
    color: #166534;
}

.prob-sol-body {
    padding: 1rem 1.2rem;
    font-size: .92rem;
    line-height: 1.75;
    color: var(--c-text);
    background: linear-gradient(180deg, #f7fff8 0%, var(--c-white) 80%);
}

.prob-sol-body> :first-child {
    margin-top: 0;
}

.prob-sol-body> :last-child {
    margin-bottom: 0;
}

/* ── Responsive prob-* ── */
@media (max-width: 575px) {
    .prob-header {
        padding: 1.5rem 1.25rem;
    }

    .prob-title {
        font-size: 1.4rem;
    }

    .prob-stats {
        gap: 1rem;
    }

    .prob-part-header {
        padding: .85rem 1rem;
        gap: .75rem;
    }

    .prob-part-body {
        padding: 1rem 1rem .75rem;
    }

    .prob-question-header {
        gap: .75rem;
    }
}