:root {
    --color-bg: #0a0e14;
    --color-surface: #15191f;
    --color-surface-bright: #1f2430;
    --color-primary: #e63946;
    --color-primary-dim: rgba(230, 57, 70, 0.18);
    --color-secondary: #ff5a5f;
    --color-accent: #ff4444;
    --color-text: #d9d9d9;
    --color-text-muted: #8a919e;
    --font-mono: 'JetBrains Mono', monospace;
    --font-sans: 'IBM Plex Sans', sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
    font-family: var(--font-sans);
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    overflow-x: hidden;
}

/* Grid backdrop */
body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-image:
        linear-gradient(rgba(230, 57, 70, 0.035) 1px, transparent 1px),
        linear-gradient(90deg, rgba(230, 57, 70, 0.035) 1px, transparent 1px);
    background-size: 52px 52px;
    pointer-events: none;
    z-index: 0;
}

.container {
    max-width: 1160px;
    margin: 0 auto;
    padding: 0 2rem;
    position: relative;
    z-index: 1;
}

a { color: inherit; }

.b1 { font-weight: 600; }
.b1 .n { color: var(--color-primary); }
.b1 .w { color: var(--color-text); }

/* Header */
header {
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--color-primary-dim);
    background: rgba(10, 14, 20, 0.85);
    backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.7rem;
    text-decoration: none;
}

.brand svg { width: 42px; height: 42px; display: block; }

.brand .wordmark {
    font-family: var(--font-mono);
    font-size: 1.8rem;
    font-weight: 700;
    letter-spacing: -0.03em;
}

.brand .wordmark .num { color: var(--color-primary); }
.brand .wordmark .tld { color: var(--color-text-muted); }

nav a {
    color: var(--color-text-muted);
    text-decoration: none;
    margin-left: 2rem;
    font-size: 0.85rem;
    font-weight: 500;
    font-family: var(--font-mono);
    transition: color 0.25s ease;
}

nav a:hover { color: var(--color-primary); }
nav a.active { color: var(--color-text); }

/* Hero */
.hero {
    padding: 7rem 0 5rem;
    position: relative;
}

.hero::after {
    content: '';
    position: absolute;
    top: -4%;
    right: -8%;
    width: 620px;
    height: 620px;
    background: radial-gradient(circle, rgba(230, 57, 70, 0.12) 0%, transparent 68%);
    pointer-events: none;
    animation: pulse 9s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); opacity: 0.55; }
    50% { transform: scale(1.12); opacity: 0.85; }
}

.hero-copy { position: relative; z-index: 1; }

.hero-mark {
    position: absolute;
    right: -2.5rem;
    top: 50%;
    transform: translateY(-50%);
    width: 460px;
    height: 460px;
    opacity: 0.5;
    pointer-events: none;
    z-index: 0;
}

.eyebrow {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    letter-spacing: 0.18em;
    text-transform: uppercase;
    color: var(--color-primary);
    margin-bottom: 1.4rem;
}

.hero h1 {
    font-size: 3.9rem;
    font-weight: 700;
    line-height: 1.08;
    margin-bottom: 1.5rem;
    font-family: var(--font-mono);
    letter-spacing: -0.035em;
    max-width: 18ch;
}

.hero h1 .highlight {
    background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero .promise {
    font-family: var(--font-mono);
    font-size: 1.05rem;
    color: var(--color-text);
    margin-bottom: 1.3rem;
    line-height: 1.7;
}

.hero .promise .accent { color: var(--color-primary); }

.hero .tagline {
    font-size: 1.3rem;
    color: var(--color-text-muted);
    margin-bottom: 2.6rem;
    max-width: 640px;
}

.cta-row {
    display: flex;
    gap: 1.2rem;
    flex-wrap: wrap;
}

.btn {
    padding: 1rem 2.1rem;
    font-family: var(--font-mono);
    font-weight: 600;
    font-size: 0.95rem;
    text-decoration: none;
    border: 2px solid var(--color-primary);
    color: var(--color-primary);
    background: transparent;
    transition: all 0.25s ease;
    display: inline-block;
}

.btn:hover {
    background: var(--color-primary);
    color: var(--color-bg);
    transform: translateY(-2px);
    box-shadow: 0 10px 30px rgba(230, 57, 70, 0.25);
}

.btn.ghost {
    border-color: var(--color-text-muted);
    color: var(--color-text-muted);
}

.btn.ghost:hover {
    border-color: var(--color-secondary);
    background: transparent;
    color: var(--color-secondary);
    box-shadow: none;
}

/* Sub-page hero (Technology / Standards) */
.page-hero {
    padding: 5rem 0 3rem;
    border-bottom: 1px solid var(--color-primary-dim);
}

.page-hero h1 {
    font-size: 2.8rem;
    font-family: var(--font-mono);
    font-weight: 700;
    letter-spacing: -0.03em;
    margin-bottom: 1.2rem;
    max-width: 20ch;
}

.page-hero p {
    color: var(--color-text-muted);
    font-size: 1.2rem;
    max-width: 680px;
}

/* Section scaffolding */
section.block { padding: 5.5rem 0; }
section.alt { background: var(--color-surface); }

.section-header { margin-bottom: 3.2rem; max-width: 760px; }

.section-header h2 {
    font-size: 2.3rem;
    font-weight: 700;
    font-family: var(--font-mono);
    letter-spacing: -0.02em;
    margin-bottom: 1rem;
}

.section-header p { color: var(--color-text-muted); font-size: 1.05rem; }

/* Feature grid */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1.5rem;
}

.card {
    padding: 2.2rem;
    background: var(--color-surface-bright);
    border: 1px solid var(--color-primary-dim);
    border-left: 3px solid var(--color-primary);
    transition: transform 0.25s ease, border-color 0.25s ease;
    position: relative;
    overflow: hidden;
}

.card:hover { transform: translateY(-4px); border-color: var(--color-primary); }

.card .tag {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--color-primary);
    margin-bottom: 1rem;
    display: block;
}

.card h3 { font-size: 1.25rem; margin-bottom: 0.75rem; font-weight: 600; }
.card p { color: var(--color-text-muted); font-size: 0.98rem; line-height: 1.7; }

/* Audience tiles */
.audience-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.2rem;
}

.tile {
    padding: 1.8rem;
    background: var(--color-surface);
    border-left: 3px solid var(--color-secondary);
}

.tile h4 {
    font-family: var(--font-mono);
    font-size: 1.05rem;
    color: var(--color-secondary);
    margin-bottom: 0.6rem;
}

.tile p { color: var(--color-text-muted); font-size: 0.92rem; }

section.alt .tile { background: var(--color-surface-bright); }

/* Problem callout + pull-quote */
.callout {
    padding: 2.6rem;
    background: var(--color-surface-bright);
    border: 1px solid var(--color-primary-dim);
    border-left: 4px solid var(--color-primary);
    margin-bottom: 2rem;
}

.callout p { color: var(--color-text-muted); line-height: 1.8; max-width: 760px; }
.callout strong { color: var(--color-text); }

.pull-quote {
    font-family: var(--font-mono);
    font-size: 1.35rem;
    line-height: 1.6;
    color: var(--color-text);
    border-left: 4px solid var(--color-primary);
    padding: 0.4rem 0 0.4rem 1.6rem;
    margin: 0 auto;
    max-width: 760px;
}

/* Two-column value (users free / receivers pay) */
.split {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 1.5rem;
}

/* Diagram figure */
figure.diagram {
    margin: 0 0 1.5rem;
    background: var(--color-surface-bright);
    border: 1px solid var(--color-primary-dim);
    padding: 1.8rem;
}

figure.diagram img,
figure.diagram svg { width: 100%; height: auto; display: block; }

figure.diagram figcaption {
    color: var(--color-text-muted);
    font-family: var(--font-mono);
    font-size: 0.82rem;
    text-align: center;
    margin-top: 1.1rem;
}

/* Capability rows */
.capability {
    display: grid;
    grid-template-columns: 3rem 1fr;
    gap: 1.4rem;
    padding: 1.8rem 0;
    border-bottom: 1px solid var(--color-primary-dim);
    align-items: start;
}

.capability:last-child { border-bottom: none; }

.capability .num {
    font-family: var(--font-mono);
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1;
}

.capability h3 { font-size: 1.3rem; margin-bottom: 0.5rem; font-weight: 600; }
.capability p { color: var(--color-text-muted); }

/* Prose + spec list (Standards) */
.prose { max-width: 760px; }
.prose p { color: var(--color-text-muted); line-height: 1.8; margin-bottom: 1.4rem; }
.prose a { color: var(--color-primary); text-decoration: none; }
.prose a:hover { text-decoration: underline; }

.spec-list { list-style: none; margin: 2rem 0; }

.spec-list li {
    padding: 1rem 0 1rem 1.4rem;
    border-left: 3px solid var(--color-primary-dim);
    margin-bottom: 0.7rem;
    color: var(--color-text-muted);
}

.spec-list li .name {
    font-family: var(--font-mono);
    color: var(--color-primary);
    font-weight: 500;
    margin-right: 0.6rem;
}

/* Open source / generic card */
.os-card {
    padding: 2.8rem;
    background: var(--color-surface-bright);
    border: 1px solid var(--color-primary-dim);
    border-left: 4px solid var(--color-primary);
}

.os-card p {
    color: var(--color-text-muted);
    line-height: 1.8;
    margin-bottom: 1.6rem;
    max-width: 760px;
}

.os-links { display: flex; gap: 1rem; flex-wrap: wrap; }

.os-links a {
    font-family: var(--font-mono);
    font-size: 0.9rem;
    text-decoration: none;
    color: var(--color-primary);
    border: 1px solid var(--color-primary-dim);
    padding: 0.6rem 1.3rem;
    transition: all 0.25s ease;
}

.os-links a:hover { border-color: var(--color-primary); background: var(--color-primary-dim); }

.os-card h3 {
    font-size: 1.55rem;
    font-family: var(--font-mono);
    letter-spacing: -0.01em;
    margin-bottom: 1rem;
}

.free-badge {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--color-bg);
    background: var(--color-primary);
    padding: 0.35rem 0.9rem;
    border-radius: 2px;
    margin-bottom: 1.3rem;
}

/* CTA */
.cta { padding: 7rem 0; text-align: center; }
.cta h2 { font-size: 2.6rem; font-family: var(--font-mono); margin-bottom: 1.4rem; letter-spacing: -0.02em; }
.cta p { color: var(--color-text-muted); font-size: 1.1rem; max-width: 560px; margin: 0 auto 2.6rem; }

/* Footer */
footer {
    padding: 2.6rem 0;
    border-top: 1px solid var(--color-primary-dim);
    background: var(--color-surface);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1.5rem;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--color-text-muted);
}

.footer-content .wordmark { color: var(--color-text); }
.footer-content .wordmark .num { color: var(--color-primary); font-weight: 700; }

.footer-links a { text-decoration: none; margin-left: 1.6rem; transition: color 0.25s ease; }
.footer-links a:hover { color: var(--color-primary); }

html { scroll-behavior: smooth; }
::selection { background: var(--color-primary); color: var(--color-bg); }

@media (max-width: 768px) {
    .hero { padding: 4.5rem 0 3.5rem; }
    .hero h1 { font-size: 2.4rem; }
    .hero .tagline { font-size: 1.1rem; }
    .page-hero h1 { font-size: 2rem; }
    .section-header h2 { font-size: 1.8rem; }
    nav { display: none; }
    .hero-mark { display: none; }
    .cta h2 { font-size: 1.9rem; }
    .footer-content { flex-direction: column; text-align: center; }
    .footer-links a { margin: 0 0.8rem; }
}