/* DevMath — ressource pédagogique maths & informatique */
:root{
  --ink:#1a1a24;
  --ink-soft:#3a3a48;
  --ink-muted:#6a6a78;
  --paper:#fbfaf6;
  --paper-warm:#f4f1e8;
  --line:#dcd8cc;
  --line-dark:#b8b2a0;
  --accent:#c84848;
  --accent-dark:#a83535;
  --math:#2e5d8f;
  --math-dark:#1d4269;
  --code-bg:#f4f1e8;
  --code-border:#dcd8cc;
  --shadow:0 4px 16px rgba(26,26,36,.08);
  --shadow-lg:0 10px 30px rgba(26,26,36,.12);
  --radius:4px;
  --radius-lg:10px;
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:"Source Serif Pro",Charter,Georgia,"Iowan Old Style",serif;color:var(--ink);background:var(--paper);line-height:1.7;font-size:17px;-webkit-font-smoothing:antialiased}
img{max-width:100%;height:auto;display:block}
a{color:var(--accent);text-decoration:none;border-bottom:1px solid rgba(200,72,72,.25);transition:all .15s}
a:hover{border-bottom-color:var(--accent)}
h1,h2,h3,h4{font-family:"Source Serif Pro",Charter,Georgia,serif;color:var(--ink);line-height:1.22;margin:0 0 .5em;letter-spacing:-.005em;font-weight:700}
h1{font-size:2.4rem;font-weight:800}
h2{font-size:1.6rem}
h3{font-size:1.2rem}
p{margin:0 0 1em}
code{font-family:"JetBrains Mono","SF Mono",Consolas,Monaco,monospace;background:var(--code-bg);border:1px solid var(--code-border);padding:.12em .4em;border-radius:3px;font-size:.88em;color:var(--ink)}
pre{background:var(--code-bg);border:1px solid var(--code-border);padding:1rem 1.2rem;border-radius:var(--radius);overflow-x:auto;font-size:.88rem;line-height:1.5;margin:1.2rem 0}
pre code{background:none;border:0;padding:0;font-size:1em}
.container{width:100%;max-width:1120px;margin:0 auto;padding:0 1.5rem}
.container-narrow{max-width:720px;margin:0 auto;padding:0 1.5rem}

/* MathJax ajustements */
.MathJax{font-size:1.05em !important}
mjx-container[jax="CHTML"][display="true"]{margin:1.2rem 0 !important;overflow-x:auto;overflow-y:hidden;padding:.3rem 0}

/* Header */
.site-header{background:var(--paper);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:50}
.site-header .inner{display:flex;align-items:center;justify-content:space-between;padding:1rem 1.5rem;max-width:1120px;margin:0 auto}
.logo{display:flex;align-items:center;gap:.6rem;font-family:"Source Serif Pro",Charter,Georgia,serif;font-size:1.25rem;color:var(--ink);font-weight:800;letter-spacing:-.01em;border-bottom:0}
.logo:hover{border-bottom:0}
.logo-mark{flex-shrink:0;width:36px;height:36px}
.logo .sub{color:var(--accent);font-weight:400;font-style:italic;font-size:.88em}
.nav{display:flex;align-items:center;gap:1.7rem}
.nav a{color:var(--ink-soft);font-family:-apple-system,BlinkMacSystemFont,sans-serif;font-weight:500;font-size:.92rem;border-bottom:0}
.nav a:hover{color:var(--accent)}
.nav-toggle{display:none;background:none;border:0;font-size:1.5rem;cursor:pointer;color:var(--ink)}
.has-dropdown{position:relative;padding:1rem 0}
.has-dropdown > a::after{content:" \25BE";font-size:.75em;color:var(--ink-muted);display:inline-block;margin-left:.15em}
.dropdown{position:absolute;top:100%;left:0;background:#fff;border:1px solid var(--line);box-shadow:var(--shadow);min-width:320px;padding:.5rem 0;visibility:hidden;opacity:0;transform:translateY(-4px);transition:opacity .15s,transform .15s,visibility .15s;list-style:none;margin:0;z-index:60;border-radius:var(--radius)}
.has-dropdown:hover .dropdown,.has-dropdown:focus-within .dropdown{visibility:visible;opacity:1;transform:translateY(0)}
.dropdown a{display:block;padding:.5rem 1.2rem;font-size:.88rem;font-weight:500;color:var(--ink-soft);border-bottom:0}
.dropdown a:hover{background:var(--paper-warm);color:var(--accent)}

/* Hero (accueil) */
.hero{padding:5rem 0 4rem;text-align:center;position:relative;overflow:hidden;background:linear-gradient(180deg,var(--paper-warm) 0%,var(--paper) 100%);border-bottom:1px solid var(--line)}
.hero .eyebrow{display:inline-block;font-size:.8rem;text-transform:uppercase;letter-spacing:.15em;color:var(--accent);font-weight:600;margin-bottom:1rem;font-family:-apple-system,sans-serif;background:rgba(200,72,72,.08);padding:.4rem 1rem;border-radius:999px}
.hero h1{font-size:3.6rem;max-width:820px;margin:0 auto 1.2rem;line-height:1.1;letter-spacing:-.02em}
.hero .lead{font-size:1.2rem;color:var(--ink-soft);font-style:italic;max-width:640px;margin:1rem auto 2.5rem;line-height:1.6}
.hero-math{font-family:"Source Serif Pro",Georgia,serif;font-size:1.4rem;color:var(--math);margin:1rem 0;letter-spacing:.05em}
.hero .cta-row{display:flex;gap:1rem;justify-content:center;flex-wrap:wrap}
.hero .btn-primary{background:var(--ink);color:var(--paper);padding:.85rem 1.8rem;font-weight:600;border-radius:999px;display:inline-flex;align-items:center;gap:.4rem;transition:all .15s;font-size:.95rem;border-bottom:0}
.hero .btn-primary:hover{background:var(--accent);color:var(--paper)}
.hero .btn-secondary{color:var(--ink);padding:.85rem 1.8rem;font-weight:600;border:1.5px solid var(--ink);border-radius:999px;background:transparent;transition:all .15s;font-size:.95rem;border-bottom:1.5px solid var(--ink)}
.hero .btn-secondary:hover{background:var(--ink);color:var(--paper)}

/* Sections */
.section{padding:4rem 0;position:relative}
.section.bg-warm{background:var(--paper-warm)}
.section-head{max-width:760px;margin:0 auto 3rem;text-align:center}
.section-head .eyebrow{display:inline-block;font-size:.78rem;text-transform:uppercase;letter-spacing:.15em;color:var(--accent);font-weight:600;margin-bottom:.6rem;font-family:-apple-system,sans-serif}
.section-head h2{font-size:2rem;margin-bottom:.8rem}
.section-head p{color:var(--ink-soft);font-size:1.05rem}

/* Hub cards (accueil + hubs) */
.grid{display:grid;gap:1.5rem}
.grid-2{grid-template-columns:repeat(2,1fr)}
.grid-3{grid-template-columns:repeat(3,1fr)}
.hub-card{background:#fff;border:1px solid var(--line);padding:2rem 2rem 2.2rem;border-radius:var(--radius-lg);transition:all .2s;color:inherit;display:flex;flex-direction:column;border-bottom:1px solid var(--line)}
.hub-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg);border-color:var(--ink)}
.hub-card .num{font-family:"Source Serif Pro",Georgia,serif;font-size:2.2rem;font-weight:800;color:var(--accent);line-height:1;margin-bottom:.6rem}
.hub-card h3{font-size:1.35rem;margin-bottom:.5rem}
.hub-card p{font-size:.98rem;color:var(--ink-soft);margin-bottom:1.2rem;flex:1;line-height:1.7}
.hub-card .more{color:var(--ink);font-family:-apple-system,sans-serif;font-weight:600;font-size:.86rem;border-bottom:2px solid var(--accent);padding-bottom:.1rem;align-self:flex-start;text-transform:uppercase;letter-spacing:.05em}

/* Article card (liste hub) */
.art-list{list-style:none;padding:0;margin:0}
.art-list li{padding:1.4rem 0;border-bottom:1px solid var(--line)}
.art-list li:last-child{border-bottom:0}
.art-list h3{font-size:1.2rem;margin:0 0 .3rem}
.art-list h3 a{color:var(--ink);border-bottom:0}
.art-list h3 a:hover{color:var(--accent)}
.art-list p{color:var(--ink-soft);font-size:.98rem;margin:0}

/* Page hero (article) */
.page-hero{padding:3rem 0 2.5rem;background:var(--paper-warm);border-bottom:1px solid var(--line)}
.page-hero .eyebrow{display:inline-block;font-size:.76rem;text-transform:uppercase;letter-spacing:.15em;color:var(--accent);font-weight:600;margin-bottom:.8rem;font-family:-apple-system,sans-serif}
.page-hero h1{font-size:2.3rem;max-width:820px;margin:0;line-height:1.2}
.page-hero .subtitle{color:var(--ink-soft);font-style:italic;font-size:1.08rem;max-width:680px;margin:1rem 0 0;line-height:1.6}

/* Breadcrumb */
.breadcrumb{font-size:.86rem;color:var(--ink-muted);padding:.8rem 0;background:var(--paper-warm);border-bottom:1px solid var(--line);font-family:-apple-system,sans-serif}
.breadcrumb a{color:var(--ink-muted);border-bottom:0}
.breadcrumb a:hover{color:var(--accent)}
.breadcrumb .sep{margin:0 .4rem;color:var(--line)}

/* Article */
.article{padding:3rem 0 4rem}
.article h2{font-size:1.7rem;margin-top:2.5rem;color:var(--ink);border-bottom:2px solid var(--line);padding-bottom:.5rem}
.article h3{font-size:1.2rem;margin-top:1.8rem;color:var(--ink-soft)}
.article p{font-size:1.05rem;line-height:1.75;color:var(--ink)}
.article ul,.article ol{padding-left:1.5rem}
.article li{margin-bottom:.5rem;line-height:1.7}
.article blockquote{border-left:3px solid var(--accent);background:var(--paper-warm);padding:1.3rem 1.6rem;margin:1.8rem 0;color:var(--ink-soft);font-style:italic}
.article .intro{font-size:1.2rem;color:var(--ink-soft);margin-bottom:2rem;line-height:1.7;padding-bottom:1.5rem;border-bottom:1px solid var(--line);font-style:italic}
.article .info-box{background:var(--paper-warm);border-radius:var(--radius);padding:1.3rem 1.6rem;margin:2rem 0;border-left:3px solid var(--math)}
.article .info-box h3{color:var(--math-dark);margin-top:0;font-size:.95rem;text-transform:uppercase;letter-spacing:.08em;font-family:-apple-system,sans-serif;font-weight:700}

/* 2-col TOC */
.article-wrap{display:grid;grid-template-columns:1fr 240px;gap:3rem;align-items:start}
.article-main{min-width:0;max-width:720px}
.article-toc{position:sticky;top:80px;max-height:calc(100vh - 100px);overflow-y:auto;padding:1.4rem 1.3rem;background:#fff;border:1px solid var(--line);border-radius:var(--radius-lg);font-size:.9rem}
.article-toc h3{font-family:-apple-system,sans-serif;font-size:.76rem;text-transform:uppercase;letter-spacing:.12em;color:var(--accent);margin:0 0 .9rem;font-weight:700}
.article-toc ol{list-style:none;padding:0;margin:0;counter-reset:toc}
.article-toc li{counter-increment:toc;padding:.35rem 0;border-bottom:1px dotted var(--line);position:relative}
.article-toc li:last-child{border-bottom:0}
.article-toc li::before{content:counter(toc, decimal-leading-zero);position:absolute;left:0;top:.35rem;font-size:.7rem;color:var(--accent);font-weight:700;font-family:"Source Serif Pro",serif}
.article-toc li a{display:block;padding-left:2rem;color:var(--ink-soft);font-weight:500;line-height:1.4;font-family:-apple-system,sans-serif;border-bottom:0}
.article-toc li a:hover{color:var(--accent)}

/* Related */
.related{background:var(--paper-warm);padding:3rem 0;border-top:1px solid var(--line)}
.related h3{font-family:-apple-system,sans-serif;font-size:.9rem;text-transform:uppercase;letter-spacing:.1em;color:var(--accent);margin-bottom:1rem;font-weight:700}
.related-list{list-style:none;padding:0;margin:0;display:grid;grid-template-columns:repeat(2,1fr);gap:.5rem 2rem}
.related-list li{padding:.5rem 0;border-bottom:1px dotted var(--line)}
.related-list a{color:var(--ink);font-size:.95rem;font-weight:500;border-bottom:0}
.related-list a:hover{color:var(--accent)}

/* Form */
.form-row{margin-bottom:1.2rem}
.form-row label{display:block;margin-bottom:.35rem;font-weight:600;color:var(--ink);font-size:.88rem;text-transform:uppercase;letter-spacing:.05em;font-family:-apple-system,sans-serif}
.form-row input,.form-row textarea{width:100%;padding:.8rem 1.1rem;border:1.5px solid var(--line);border-radius:var(--radius);font-family:inherit;font-size:1rem;background:#fff;color:var(--ink)}
.form-row input:focus,.form-row textarea:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 3px rgba(200,72,72,.15)}
.form-row textarea{min-height:140px;resize:vertical}
.form-submit{background:var(--ink);color:var(--paper);border:0;padding:.9rem 2rem;font-size:.92rem;font-weight:700;border-radius:999px;cursor:pointer;text-transform:uppercase;letter-spacing:.05em;font-family:-apple-system,sans-serif}
.form-submit:hover{background:var(--accent)}

/* Footer */
.site-footer{background:var(--ink);color:#bcb8ad;padding:3.5rem 0 1.5rem;margin-top:0}
.site-footer h4{color:var(--paper);font-family:-apple-system,sans-serif;font-size:.85rem;text-transform:uppercase;letter-spacing:.12em;font-weight:700;margin-bottom:1rem}
.site-footer a{color:#bcb8ad;border-bottom:0}
.site-footer a:hover{color:var(--accent)}
.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr;gap:2.5rem;margin-bottom:2rem}
.footer-grid ul{list-style:none;padding:0;margin:0}
.footer-grid li{padding:.25rem 0;font-size:.9rem}
.footer-tag{font-family:"Source Serif Pro",Georgia,serif;font-style:italic;color:#d4cfc1;margin-top:.8rem}
.footer-bottom-bar{border-top:1px solid rgba(255,255,255,.1);padding:1.5rem 0 0;display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:1rem}
.footer-utility{display:flex;flex-wrap:wrap;gap:.4rem 1.4rem;list-style:none;padding:0;margin:0}
.footer-utility li{position:relative}
.footer-utility li:not(:last-child)::after{content:"\00B7";position:absolute;right:-.95rem;color:rgba(255,255,255,.3);top:50%;transform:translateY(-50%)}
.footer-utility a{color:#bcb8ad;font-size:.84rem;font-family:-apple-system,sans-serif}
.footer-copy{color:#7a7567;font-size:.82rem;margin:0}

/* Responsive */
@media (max-width:900px){
  h1{font-size:2rem}
  .hero h1{font-size:2.6rem}
  .grid-3{grid-template-columns:repeat(2,1fr)}
  .article-wrap{grid-template-columns:1fr;gap:2rem}
  .article-toc{position:static;max-height:none;order:-1}
  .footer-grid{grid-template-columns:repeat(2,1fr);gap:2rem}
  .page-hero h1{font-size:1.8rem}
}
@media (max-width:640px){
  .nav{display:none;flex-direction:column;position:absolute;top:100%;left:0;right:0;background:var(--paper);border-bottom:1px solid var(--line);padding:1rem;gap:.8rem;align-items:stretch;box-shadow:var(--shadow)}
  .nav.open{display:flex}
  .nav-toggle{display:block}
  .dropdown{position:static;border:0;box-shadow:none;padding:.25rem 0 .25rem 1rem;visibility:visible;opacity:1;transform:none;min-width:0}
  .has-dropdown > a::after{display:none}
  .has-dropdown{padding:0}
  .grid-2,.grid-3{grid-template-columns:1fr}
  .footer-grid{grid-template-columns:1fr}
  .hero{padding:3rem 0 2.5rem}
  .hero h1{font-size:2rem}
  .section-head h2{font-size:1.6rem}
  .related-list{grid-template-columns:1fr}
  .footer-bottom-bar{flex-direction:column;text-align:center}
  .footer-utility{justify-content:center}
}