:root{
  --bg:#F5F6FB; --ink:#14162B; --ink-2:#4B5069; --line:#E1E4F0; --card:#FFFFFF;
  --lvl:#4F46E5; --c:var(--lvl);
  --def:var(--lvl); --prop:#0EA5E9; --thm:#14162B; --met:#F59E0B; --ex:#6B7280; --rem:#10B981;
  --font-d:"Bricolage Grotesque",system-ui,sans-serif; --font-b:"Figtree",system-ui,sans-serif;
  --r:18px; --r-s:10px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important;animation:none!important}}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--font-b);font-size:17px;line-height:1.6;-webkit-font-smoothing:antialiased}
a{color:var(--lvl)}
a:focus-visible,button:focus-visible{outline:3px solid var(--lvl);outline-offset:3px;border-radius:6px}
h1,h2,h3{font-family:var(--font-d);line-height:1.1;letter-spacing:-.02em;margin:0 0 .5em}
h1{font-size:clamp(2rem,4.5vw,3.4rem);font-weight:800}
h2{font-size:clamp(1.35rem,2.4vw,1.8rem);font-weight:700;margin-top:2.2em}
h3{font-size:1.15rem;font-weight:700;margin-top:1.6em}
p{margin:0 0 1em}
strong{font-weight:700}
.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}

/* ---------- barre haute ---------- */
.topbar{display:grid;grid-template-columns:1fr auto 1fr;align-items:center;gap:20px;padding:14px clamp(16px,4vw,48px);background:#fff;border-bottom:1px solid var(--line);position:sticky;top:0;z-index:20}
.brand{font-family:var(--font-d);font-weight:800;font-size:1.05rem;color:var(--ink);text-decoration:none;display:flex;align-items:center;gap:10px;white-space:nowrap}
.site-logo{justify-self:center;font-family:var(--font-d);font-weight:800;font-size:1.7rem;letter-spacing:.12em;text-decoration:none;color:var(--ink);background:linear-gradient(90deg,#7C3AED,#2563EB,#059669,#EA580C,#E11D48);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent;white-space:nowrap}
.levels-nav{justify-self:end}
.brand-mark{display:grid;place-items:center;width:34px;height:34px;border-radius:10px;background:var(--ink);color:#fff;font-size:1.2rem}
.levels-nav{display:flex;gap:6px;flex-wrap:wrap;margin-left:auto}
.levels-nav a{text-decoration:none;font-weight:700;font-size:.85rem;padding:6px 11px;border-radius:999px;color:var(--c);background:color-mix(in srgb,var(--c) 10%,#fff)}
.levels-nav a.is-current{background:var(--c);color:#fff}

/* ---------- fil d'Ariane ---------- */
.crumbs{padding:14px clamp(16px,4vw,48px) 0;font-size:.9rem}
.crumbs ol{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:4px;color:var(--ink-2)}
.crumbs li+li::before{content:"/";margin:0 8px;color:#B4B8CC}
.crumbs a{color:var(--ink-2);text-decoration:none}
.crumbs a:hover{color:var(--lvl)}

/* ---------- accueil ---------- */
.home{max-width:1180px;margin:0 auto;padding:40px clamp(16px,4vw,48px) 80px}
.hero{max-width:820px;margin-bottom:48px}
.hero-kicker{font-weight:600;color:var(--ink-2);margin-bottom:12px}
.hero h1{font-size:clamp(2.4rem,6vw,4.6rem);letter-spacing:-.03em}
.hero h1 strong{background:linear-gradient(90deg,#7C3AED,#2563EB,#059669,#EA580C,#E11D48);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero-text{font-size:1.15rem;color:var(--ink-2);max-width:66ch}
.lvl-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:18px}
.lvl-card{position:relative;display:flex;flex-direction:column;gap:6px;padding:26px 24px 22px;border-radius:var(--r);background:var(--c);color:#fff;text-decoration:none;min-height:230px;overflow:hidden;isolation:isolate;transition:transform .2s}
.lvl-card::after{content:"";position:absolute;inset:auto -40px -60px auto;width:220px;height:220px;border-radius:50%;background:rgba(255,255,255,.14);z-index:-1}
.lvl-card:hover{transform:translateY(-3px)}
.lvl-big{font-family:var(--font-d);font-weight:800;font-size:4.2rem;line-height:.9;letter-spacing:-.05em}
.lvl-name{font-family:var(--font-d);font-weight:700;font-size:1.3rem;margin-top:8px}
.lvl-pitch{opacity:.92;font-size:.95rem;line-height:1.45}
.lvl-meta{margin-top:auto;padding-top:12px;font-size:.82rem;opacity:.85;border-top:1px solid rgba(255,255,255,.35)}
.about{max-width:760px;margin-top:64px}
.about h2{margin-top:1.4em}
.about p{color:var(--ink-2)}

/* ---------- page niveau ---------- */
.level{max-width:1180px;margin:0 auto;padding:24px clamp(16px,4vw,48px) 80px}
.level-hero{display:grid;grid-template-columns:auto 1fr;gap:28px;align-items:center;padding:34px clamp(20px,3vw,40px);border-radius:var(--r);background:var(--lvl);color:#fff;margin-bottom:34px}
.level-hero .lvl-big{font-size:clamp(4rem,10vw,7rem)}
.level-hero h1{color:#fff}
.level-hero p{opacity:.95;max-width:70ch;margin:0}
.chap-list{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fill,minmax(330px,1fr));gap:14px}
.chap-card{display:flex;gap:16px;align-items:flex-start;padding:18px 18px 18px 16px;border-radius:14px;background:var(--card);border:1px solid var(--line);text-decoration:none;color:var(--ink);height:100%;position:relative}
.chap-card:hover{border-color:var(--lvl);box-shadow:0 0 0 3px color-mix(in srgb,var(--lvl) 18%,transparent)}
.chap-num{font-family:var(--font-d);font-weight:800;font-size:1.5rem;color:var(--lvl);line-height:1.2;min-width:2ch}
.chap-body{display:flex;flex-direction:column;gap:3px}
.chap-title{font-weight:700;font-family:var(--font-d);font-size:1.08rem;line-height:1.2}
.chap-desc{font-size:.9rem;color:var(--ink-2);line-height:1.4}
.tag-fig{position:absolute;top:10px;right:10px;font-size:.68rem;font-weight:700;padding:3px 8px;border-radius:999px;background:color-mix(in srgb,var(--lvl) 12%,#fff);color:var(--lvl)}
.siblings{display:flex;justify-content:space-between;gap:12px;margin-top:40px;flex-wrap:wrap}
.sib{text-decoration:none;font-weight:700;color:var(--c);padding:10px 16px;border-radius:999px;background:color-mix(in srgb,var(--c) 12%,#fff)}

/* ---------- page chapitre ---------- */
.chapter{max-width:1180px;margin:0 auto;padding:20px clamp(16px,4vw,48px) 80px;display:grid;grid-template-columns:250px minmax(0,1fr);gap:40px;align-items:start}
.side{position:sticky;top:78px;font-size:.9rem;max-height:calc(100vh - 100px);overflow:auto;padding-right:6px}
.side-title{list-style:none;cursor:default;font-family:var(--font-d);font-weight:800;font-size:1rem;display:flex;align-items:center;gap:8px;margin-bottom:10px}
.dot{width:12px;height:12px;border-radius:50%;background:var(--lvl)}
.side-toc{list-style:none;margin:0;padding:0;counter-reset:ch}
.side-toc li{counter-increment:ch;border-left:2px solid var(--line)}
.side-toc a{display:block;padding:6px 10px 6px 14px;text-decoration:none;color:var(--ink-2);line-height:1.3}
.side-toc a::before{content:counter(ch,decimal-leading-zero) " ";font-weight:700;color:#B4B8CC;font-size:.75rem}
.side-toc li.is-current{border-left-color:var(--lvl)}
.side-toc li.is-current a{color:var(--lvl);font-weight:700}
.side-toc a:hover{color:var(--ink)}
article{max-width:780px;min-width:0}
.chap-kicker{color:var(--lvl);font-weight:700;margin-bottom:6px}
.lead{font-size:1.15rem;color:var(--ink-2);max-width:66ch}
article h2{padding-top:6px;border-top:2px solid var(--line)}
article ul,article ol{padding-left:1.3em}
article li{margin-bottom:.35em}
article table{border-collapse:collapse;width:100%;margin:1em 0;font-size:.95rem}
article th,article td{border:1px solid var(--line);padding:8px 10px;text-align:left;vertical-align:top}
article th{background:color-mix(in srgb,var(--lvl) 8%,#fff)}
article code{font-family:ui-monospace,monospace;font-size:.9em;background:#EEF0F7;padding:1px 5px;border-radius:5px}
mjx-container{overflow-x:auto;overflow-y:hidden;max-width:100%}

/* encadrés */
.box{position:relative;margin:1.2em 0;padding:16px 18px 12px 20px;border-radius:var(--r-s);background:var(--card);border:1px solid var(--line);border-left:5px solid var(--bc)}
.box>b:first-child{display:block;font-family:var(--font-d);font-weight:800;color:var(--bc);margin-bottom:6px;font-size:.95rem}
.box p:last-child,.box ul:last-child{margin-bottom:0}
.box.def{--bc:var(--def);background:color-mix(in srgb,var(--def) 5%,#fff)}
.box.prop{--bc:var(--prop);background:color-mix(in srgb,var(--prop) 6%,#fff)}
.box.thm{--bc:var(--thm);background:#fff;border-color:var(--thm)}
.box.thm>b:first-child{color:var(--thm)}
.box.met{--bc:var(--met);background:color-mix(in srgb,var(--met) 7%,#fff)}
.box.ex{--bc:var(--ex);background:#F8F9FC}
.box.rem{--bc:var(--rem);background:color-mix(in srgb,var(--rem) 6%,#fff)}

/* figure */
.fig{margin:1.5em 0}
.jxgbox{width:100%;height:380px;border-radius:14px;border:1px solid var(--line);background:#fff;touch-action:none}
.fig figcaption{font-size:.9rem;color:var(--ink-2);margin-top:8px}

/* navigation chapitres */
.faq{margin-top:40px}
.faq h2{margin-bottom:12px}
.faq-item{border:1px solid var(--line);border-radius:14px;background:#fff;margin:10px 0;overflow:hidden}
.faq-item summary{list-style:none;cursor:pointer;display:flex;align-items:center;gap:12px;padding:14px 18px}
.faq-item summary::-webkit-details-marker{display:none}
.faq-item summary::after{content:"+";margin-left:auto;font-size:1.4rem;line-height:1;color:var(--lvl);font-weight:700}
.faq-item[open] summary::after{content:"–"}
.faq-item h3{font-size:1.02rem;margin:0;font-weight:700}
.faq-a{padding:0 18px 16px;color:var(--ink-2);line-height:1.6}
.pdfbar{display:flex;align-items:center;gap:16px;flex-wrap:wrap;margin:36px 0 8px;padding:18px 20px;border-radius:16px;background:#fff;border:1px solid var(--line)}
.btn-pdf{display:inline-flex;align-items:center;gap:10px;padding:12px 20px;border-radius:999px;background:var(--lvl);color:#fff;font-weight:700;text-decoration:none;box-shadow:0 6px 18px color-mix(in srgb,var(--lvl) 35%,transparent);transition:transform .15s}
.btn-pdf::before{content:"";width:18px;height:18px;background:currentColor;-webkit-mask:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='black' stroke-width='2.4' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M12 3v12m0 0l-4-4m4 4l4-4M4 17v2a2 2 0 002 2h12a2 2 0 002-2v-2'/%3E%3C/svg%3E") center/contain no-repeat;mask:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='black' stroke-width='2.4' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M12 3v12m0 0l-4-4m4 4l4-4M4 17v2a2 2 0 002 2h12a2 2 0 002-2v-2'/%3E%3C/svg%3E") center/contain no-repeat}
.btn-pdf:hover{transform:translateY(-2px)}
.pdfhint{color:var(--ink-2);font-size:.9rem}
.prevnext{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:48px}
.pn{display:flex;flex-direction:column;padding:16px 18px;border-radius:14px;background:var(--card);border:1px solid var(--line);text-decoration:none;color:var(--ink);font-weight:700;font-family:var(--font-d)}
.pn small{font-family:var(--font-b);font-weight:500;color:var(--ink-2);font-size:.8rem}
.pn.next{text-align:right;grid-column:2}
.pn:hover{border-color:var(--lvl)}

/* plan du site */
.plan{max-width:1100px;margin:0 auto;padding:24px clamp(16px,4vw,48px) 80px;columns:3;column-gap:40px}
.plan h1{column-span:all}
.plan section{break-inside:avoid;margin-bottom:24px}
.plan h2{margin-top:0;font-size:1.2rem}
.plan h2 a{color:var(--c);text-decoration:none}
.plan ul{padding-left:1.1em;font-size:.92rem}
.plan a{color:var(--ink-2);text-decoration:none}
.plan a:hover{color:var(--c)}

/* pied de page */
.footer{background:var(--ink);color:#C7CAE0;padding:40px clamp(16px,4vw,48px);font-size:.92rem}
.footer p{max-width:70ch;margin:0 auto .6em}
.footer strong{color:#fff}
.footer a{color:#fff}

.side-title::-webkit-details-marker{display:none}
@media (max-width:900px){
  .topbar{grid-template-columns:1fr;gap:10px}
  .brand{font-size:.95rem}
  .site-logo{justify-self:center;font-size:1.35rem}
  .levels-nav{justify-self:center}
  .chapter{grid-template-columns:1fr}
  .side-title{cursor:pointer;padding:10px 14px;border:1px solid var(--line);border-radius:12px;background:#fff}
  .side-title::after{content:"▾";margin-left:auto;color:var(--ink-2)}
  .side[open] .side-title::after{content:"▴"}
  .side-toc{margin-top:10px}
  .side{position:static;max-height:none}
  .side-toc{display:flex;flex-wrap:wrap;gap:4px}
  .side-toc li{border-left:0}
  .side-toc a{padding:5px 10px;border-radius:999px;background:#fff;border:1px solid var(--line)}
  .side-toc li.is-current a{background:var(--lvl);color:#fff}
  .level-hero{grid-template-columns:1fr}
  .plan{columns:1}
}
@media (max-width:560px){
  .prevnext{grid-template-columns:1fr}
  .pn.next{grid-column:1;text-align:left}
  .jxgbox{height:300px}
  body{font-size:16px}
}