* { margin: 0; padding: 0; box-sizing: border-box; }
:root {
    --black: #000000;
    --gray-900: #111111;
    --gray-700: #374151;
    --gray-600: #4b5563;
    --gray-500: #6b7280;
    --gray-400: #9ca3af;
    --gray-300: #d1d5db;
    --gray-200: #e5e7eb;
    --gray-100: #f3f4f6;
    --gray-50: #f9fafb;
    --white: #ffffff;
    --green: #16a34a;
    --red: #dc2626;
    --amber: #d97706;
    --font-sans: 'IBM Plex Sans', -apple-system, sans-serif;
    --font-mono: 'IBM Plex Mono', monospace;
}
html { scroll-behavior: smooth; }
body {
    font-family: var(--font-sans); background: var(--white);
    color: var(--black); line-height: 1.7; font-size: 16px;
    display: flex; flex-direction: column; min-height: 100vh;
}

/* Stats bar */
.stats-bar {
    display: flex; justify-content: center; gap: 2rem; flex-wrap: wrap;
    padding: 0.75rem 2rem; border-bottom: 1px solid var(--gray-200);
    font-size: 0.8rem; color: var(--gray-500);
}
.stat { display: flex; align-items: center; gap: 0.4rem; }
.stat-value { font-family: var(--font-mono); font-weight: 500; color: var(--black); }
.stat-link {
    display: flex; align-items: center; gap: 0.4rem;
    text-decoration: none; color: inherit; padding: 0.25rem 0.5rem;
    border-radius: 4px; transition: background 0.15s;
}
.stat-link:hover { background: var(--gray-100); }
.stat-link:hover .stat-value { text-decoration: underline; }

/* Header */
.paper-header {
    text-align: center; padding: 4rem 2rem 2rem;
    border-bottom: 1px solid var(--gray-200);
    max-width: 720px; margin: 0 auto;
}
.logo {
    display: inline-flex; align-items: baseline; gap: 0.25rem;
    margin-bottom: 0.25rem; text-decoration: none;
}
.logo-text { font-size: 3.92rem; font-weight: 400; letter-spacing: -0.03em; color: var(--black); }
.logo-mark {
    font-family: var(--font-mono); font-size: 2.42rem; color: var(--green);
    animation: tau-spin 10s linear infinite; display: inline-block;
}
@keyframes tau-spin { from { transform: rotateY(0deg); } to { transform: rotateY(-360deg); } }
.acronym {
    font-size: 0.75rem; font-family: var(--font-mono);
    letter-spacing: 0.02em; color: var(--gray-400); margin-bottom: 0.5rem;
}
.paper-title { font-size: 1.5rem; font-weight: 500; color: var(--black); margin-bottom: 0.25rem; }
.paper-subtitle { font-size: 0.9rem; color: var(--gray-500); font-style: italic; }

/* Main */
main {
    flex: 1; max-width: 720px; margin: 0 auto;
    padding: 2rem 2rem 5rem; width: 100%;
}

/* Quick start hero */
.hero {
    background: var(--gray-900); color: var(--gray-100);
    border-radius: 8px; padding: 2rem 2.5rem; margin: 2rem 0 3rem;
    font-family: var(--font-mono); font-size: 0.85rem; line-height: 2;
}
.hero .comment { color: var(--gray-500); }
.hero .prompt { color: var(--green); user-select: none; }
.hero-label {
    font-family: var(--font-sans); font-size: 0.7rem; font-weight: 600;
    text-transform: uppercase; letter-spacing: 0.1em; color: var(--gray-400);
    margin-bottom: 1rem; display: block;
}

/* Sections */
h2 {
    font-size: 1.2rem; font-weight: 600; margin-top: 3.5rem;
    margin-bottom: 0.75rem; padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--gray-200);
}
h2 .num {
    font-family: var(--font-mono); font-size: 0.8rem; font-weight: 500;
    color: var(--gray-400); margin-right: 0.5rem;
}
h3 { font-size: 1rem; font-weight: 600; margin-top: 1.75rem; margin-bottom: 0.5rem; }
p { margin-bottom: 1rem; color: var(--gray-700); }
a { color: var(--black); }

/* Code */
pre {
    background: var(--gray-900); color: var(--gray-100);
    padding: 1.25rem 1.5rem; border-radius: 6px; overflow-x: auto;
    font-family: var(--font-mono); font-size: 0.8rem;
    line-height: 1.9; margin: 1rem 0 1.5rem;
}
pre .c { color: var(--gray-500); }
pre .p { color: var(--green); user-select: none; }
code {
    font-family: var(--font-mono); font-size: 0.85em;
    background: var(--gray-100); padding: 0.15rem 0.4rem; border-radius: 3px;
}
pre code { background: none; padding: 0; font-size: 1em; }

/* Tables */
table { width: 100%; border-collapse: collapse; margin: 1rem 0 1.5rem; font-size: 0.85rem; }
th, td { padding: 0.6rem 0.75rem; text-align: left; border-bottom: 1px solid var(--gray-200); }
th {
    font-weight: 600; background: var(--gray-50); font-size: 0.72rem;
    text-transform: uppercase; letter-spacing: 0.06em; color: var(--gray-500);
}
td { font-family: var(--font-mono); color: var(--gray-700); font-size: 0.82rem; }
td:last-child { font-family: var(--font-sans); }

/* Callouts */
.note {
    background: var(--gray-50); border-left: 3px solid var(--gray-300);
    padding: 0.9rem 1.15rem; margin: 1.25rem 0; font-size: 0.88rem; color: var(--gray-600);
}
.note strong { color: var(--gray-700); }
.warning {
    background: #fefce8; border-left: 3px solid var(--amber);
    padding: 0.9rem 1.15rem; margin: 1.25rem 0; font-size: 0.88rem; color: #78350f;
}
.warning strong { color: #451a03; }
.danger {
    background: #fef2f2; border-left: 3px solid var(--red);
    padding: 0.9rem 1.15rem; margin: 1.25rem 0; font-size: 0.88rem; color: #7f1d1d;
}
.danger strong { color: #450a0a; }

/* OS tabs */
.os { font-family: var(--font-mono); font-size: 0.7rem; font-weight: 600;
    text-transform: uppercase; letter-spacing: 0.06em; color: var(--gray-400);
    background: var(--gray-50); border: 1px solid var(--gray-200);
    padding: 0.12rem 0.5rem; border-radius: 3px; margin-right: 0.25rem;
}

/* Lists */
ul, ol { margin: 0.75rem 0 1.25rem 1.5rem; color: var(--gray-700); }
li { margin-bottom: 0.4rem; }

/* Separator */
hr { border: none; border-top: 1px solid var(--gray-200); margin: 3rem 0; }

/* Footer */
footer {
    padding: 1.5rem 2rem; border-top: 1px solid var(--gray-200);
    font-size: 0.8rem; color: var(--gray-400); text-align: center;
}
footer a { color: var(--gray-500); text-decoration: none; margin: 0 0.5rem; }
footer .quote { font-style: italic; margin-bottom: 0.25rem; }
footer a:hover { color: var(--black); }
footer p { margin-bottom: 0; }
footer p:last-child { margin-top: 0.5rem; }

/* Responsive */
@media (max-width: 600px) {
    .stats-bar {
        gap: 0.5rem 1.2rem; font-size: 0.65rem;
        padding: 0.5rem 1rem;
    }
    .stat, .stat-link { gap: 0.25rem; }
    .stat-link { padding: 0.2rem 0.3rem; }
    .paper-header { padding: 2.5rem 1.25rem 1.5rem; }
    .logo-text { font-size: 2.5rem; }
    .logo-mark { font-size: 1.5rem; }
    .acronym { font-size: 0.55rem; }
    .paper-title { font-size: 1.2rem; }
    .paper-subtitle { font-size: 0.75rem; }
    main { padding: 1.25rem 1rem 2.5rem; }
    pre { padding: 0.75rem; font-size: 0.68rem; overflow-x: auto; }
    .hero { padding: 1rem; font-size: 0.75rem; }
    .hero-label { font-size: 0.55rem; }
    h2 { font-size: 1.1rem; }
    table { font-size: 0.75rem; }
    .note, .danger { padding: 0.75rem; font-size: 0.8rem; }
    details summary { font-size: 0.7rem; padding: 0.6rem; }
}
/* Details dropdown for step-by-step */
details summary::-webkit-details-marker { display: none; }
details summary::marker { display: none; content: ""; }
details summary:hover { border-color: var(--gray-400); color: var(--black); }
details[open] summary { color: var(--black); border-color: var(--gray-400); margin-bottom: 0; }