:root{
  --red:#ef3b2d; --red-dark:#b91c1c; --ink:#1a202c; --muted:#64748b;
  --bg:#ffffff; --bg-alt:#f8fafc; --border:#e2e8f0; --code-bg:#0f172a;
  --sidebar-w:290px; --accent:#f97066; --ok:#16a34a; --purple:#7c3aed;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:'Inter',-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;
  color:var(--ink);background:var(--bg);line-height:1.7;font-size:16px}
a{color:var(--red);text-decoration:none}
a:hover{text-decoration:underline}

/* Layout */
.layout{display:flex;min-height:100vh}
.sidebar{width:var(--sidebar-w);background:var(--bg-alt);border-right:1px solid var(--border);
  position:fixed;top:0;left:0;height:100vh;overflow-y:auto;padding:24px 0}
.sidebar-brand{padding:0 24px 20px;border-bottom:1px solid var(--border);margin-bottom:16px}
.sidebar-brand h1{font-size:19px;font-weight:800;color:var(--ink);display:flex;align-items:center;gap:9px}
.sidebar-brand .logo{width:30px;height:30px;background:linear-gradient(135deg,var(--red),var(--red-dark));
  border-radius:7px;display:flex;align-items:center;justify-content:center;color:#fff;font-weight:900;font-size:16px;flex-shrink:0}
.sidebar-brand p{font-size:12.5px;color:var(--muted);margin-top:5px}
.nav-section{padding:14px 24px 6px;font-size:11px;font-weight:700;text-transform:uppercase;
  letter-spacing:.06em;color:var(--muted)}
.nav a{display:block;padding:7px 24px;color:#334155;font-size:14px;border-left:3px solid transparent}
.nav a:hover{background:#fff;color:var(--red);text-decoration:none}
.nav a.active{border-left-color:var(--red);color:var(--red);font-weight:600;background:#fff}
.nav a .day{display:inline-block;width:22px;color:var(--muted);font-size:12px;font-weight:600}

/* Main */
.main{margin-left:var(--sidebar-w);flex:1;max-width:calc(100% - var(--sidebar-w))}
.content{max-width:860px;margin:0 auto;padding:52px 48px 120px}
section{scroll-margin-top:24px;margin-bottom:56px}
.hero{background:linear-gradient(135deg,#1e293b,#0f172a);color:#fff;border-radius:18px;
  padding:48px 44px;margin-bottom:44px;position:relative;overflow:hidden}
.hero::after{content:"";position:absolute;right:-40px;top:-40px;width:200px;height:200px;
  background:radial-gradient(circle,rgba(239,59,45,.35),transparent 70%)}
.hero h1{font-size:34px;font-weight:800;margin-bottom:14px;line-height:1.2}
.hero p{font-size:16.5px;color:#cbd5e1;max-width:620px}
.hero .badges{margin-top:22px;display:flex;gap:10px;flex-wrap:wrap}
.hero .badge{background:rgba(255,255,255,.12);padding:6px 13px;border-radius:20px;font-size:13px;color:#fff}

h2{font-size:27px;font-weight:800;margin:8px 0 18px;padding-bottom:10px;border-bottom:2px solid var(--border)}
h3{font-size:20px;font-weight:700;margin:28px 0 12px;color:var(--ink)}
h4{font-size:16px;font-weight:700;margin:20px 0 8px;color:#334155}
p{margin-bottom:14px}
ul,ol{margin:0 0 16px 24px}
li{margin-bottom:7px}

/* Day card */
.day-card{background:var(--bg-alt);border:1px solid var(--border);border-radius:14px;
  padding:26px 28px;margin-bottom:22px;border-left:5px solid var(--red)}
.day-card .day-head{display:flex;align-items:center;gap:14px;margin-bottom:14px}
.day-card .day-num{background:var(--red);color:#fff;width:52px;height:52px;border-radius:12px;
  display:flex;flex-direction:column;align-items:center;justify-content:center;flex-shrink:0;line-height:1.1}
.day-card .day-num small{font-size:9px;text-transform:uppercase;opacity:.85}
.day-card .day-num b{font-size:22px;font-weight:800}
.day-card .day-title h3{margin:0;font-size:19px}
.day-card .day-title .meta{font-size:12.5px;color:var(--muted);margin-top:2px}

/* Callouts */
.callout{border-radius:10px;padding:15px 18px;margin:16px 0;font-size:14.5px;border:1px solid}
.callout.tip{background:#f0fdf4;border-color:#bbf7d0;color:#14532d}
.callout.warn{background:#fffbeb;border-color:#fde68a;color:#78350f}
.callout.info{background:#eff6ff;border-color:#bfdbfe;color:#1e3a8a}
.callout b{display:block;margin-bottom:3px}

/* Code */
pre{background:var(--code-bg);color:#e2e8f0;border-radius:10px;padding:18px 20px;overflow-x:auto;
  font-size:13.5px;line-height:1.6;margin:14px 0;font-family:'JetBrains Mono','Fira Code',monospace}
code{font-family:'JetBrains Mono','Fira Code',monospace;font-size:.88em}
:not(pre)>code{background:#f1f5f9;color:var(--red-dark);padding:2px 6px;border-radius:5px}
pre code{background:none;color:inherit;padding:0}
.code-label{background:#1e293b;color:#94a3b8;font-size:11.5px;padding:6px 20px;border-radius:10px 10px 0 0;
  margin:14px 0 -14px;font-family:'JetBrains Mono',monospace;display:inline-block}
.tok-c{color:#64748b}.tok-k{color:#f472b6}.tok-s{color:#86efac}.tok-f{color:#93c5fd}.tok-v{color:#fbbf24}

/* Video */
.video{display:flex;gap:13px;align-items:center;background:#fef2f2;border:1px solid #fecaca;
  border-radius:10px;padding:13px 16px;margin:14px 0}
.video .yt{width:44px;height:44px;background:var(--red);border-radius:9px;display:flex;
  align-items:center;justify-content:center;flex-shrink:0}
.video .yt svg{width:22px;height:22px;fill:#fff}
.video .vinfo b{display:block;font-size:14.5px;color:var(--ink)}
.video .vinfo span{font-size:12.5px;color:var(--muted)}

/* Table */
.tbl{width:100%;border-collapse:collapse;margin:16px 0;font-size:14px}
.tbl th{background:var(--ink);color:#fff;text-align:left;padding:10px 14px;font-weight:600}
.tbl td{border:1px solid var(--border);padding:10px 14px;vertical-align:top}
.tbl tr:nth-child(even){background:var(--bg-alt)}

/* pill */
.pill{display:inline-block;padding:3px 10px;border-radius:20px;font-size:12px;font-weight:600}
.pill.free{background:#dcfce7;color:#166534}.pill.paid{background:#fee2e2;color:#991b1b}
.pill.ver{background:#ede9fe;color:#5b21b6}

.toc-top{display:none}
@media(max-width:900px){
  .sidebar{transform:translateX(-100%);transition:.3s;z-index:100;box-shadow:2px 0 20px rgba(0,0,0,.15)}
  .sidebar.open{transform:translateX(0)}
  .main{margin-left:0;max-width:100%}
  .content{padding:28px 20px 100px}
  .toc-top{display:flex;position:sticky;top:0;background:#fff;border-bottom:1px solid var(--border);
    padding:14px 20px;z-index:50;align-items:center;gap:12px}
  .toc-top button{background:var(--red);color:#fff;border:none;padding:8px 14px;border-radius:8px;font-size:14px;font-weight:600}
  .hero{padding:32px 24px}.hero h1{font-size:26px}
}
.progress-bar{position:fixed;top:0;left:var(--sidebar-w);right:0;height:3px;background:transparent;z-index:200}
.progress-bar .fill{height:100%;background:var(--red);width:0%}
@media(max-width:900px){.progress-bar{left:0}}
footer{border-top:1px solid var(--border);padding:28px 48px;text-align:center;color:var(--muted);
  font-size:13px;margin-left:var(--sidebar-w)}
@media(max-width:900px){footer{margin-left:0}}