:root {
    --brand-blue: #2563eb;
    --brand-red: #dc2626;
    --ink: #1c1c1e;
    --muted: #6b6b70;
    --line: #e5e5ea;
    --bg: #ffffff;
    --bg-soft: #f5f5f7;
    --radius: 14px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    color: var(--ink);
    background: var(--bg);
    line-height: 1.6;
    font-size: 17px;
}

@media (prefers-color-scheme: dark) {
    :root {
        --ink: #f2f2f7;
        --muted: #9a9aa0;
        --line: #2c2c2e;
        --bg: #000000;
        --bg-soft: #1c1c1e;
    }
}

.wordmark {
    font-weight: 800;
    letter-spacing: -0.02em;
    background: linear-gradient(90deg, var(--brand-blue), var(--brand-red));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

/* Header */
.site-header {
    position: sticky;
    top: 0;
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 14px 22px;
    background: color-mix(in srgb, var(--bg) 82%, transparent);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid var(--line);
}

.site-header .wordmark { font-size: 20px; text-decoration: none; }

.site-header nav {
    display: flex;
    gap: 18px;
    flex-wrap: wrap;
    align-items: center;
}

.site-header nav a {
    color: var(--muted);
    text-decoration: none;
    font-size: 15px;
    font-weight: 500;
}

.site-header nav a:hover { color: var(--ink); }

.lang-toggle {
    border: 1px solid var(--line);
    background: var(--bg-soft);
    color: var(--ink);
    font: inherit;
    font-size: 14px;
    font-weight: 600;
    padding: 5px 12px;
    border-radius: 999px;
    cursor: pointer;
}

/* Layout */
main {
    max-width: 780px;
    margin: 0 auto;
    padding: 40px 22px 80px;
}

/* Hero */
.hero {
    text-align: center;
    padding: 48px 0 32px;
}

.hero .logo {
    width: 120px;
    height: 120px;
    display: block;
    margin: 0 auto 8px;
    border-radius: 26px;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.18);
}

.hero h1 {
    font-size: clamp(38px, 8vw, 60px);
    margin: 8px 0 4px;
    letter-spacing: -0.03em;
}

.hero .tagline {
    font-size: 20px;
    color: var(--muted);
    max-width: 560px;
    margin: 12px auto 0;
}

.store-badge {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    margin-top: 26px;
    padding: 13px 24px;
    background: var(--ink);
    color: var(--bg);
    border-radius: 12px;
    text-decoration: none;
    font-weight: 600;
    font-size: 17px;
}

.store-badge.disabled {
    background: var(--bg-soft);
    color: var(--muted);
    border: 1px solid var(--line);
    cursor: default;
}

/* Feature grid */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 16px;
    margin: 40px 0;
}

.feature {
    background: var(--bg-soft);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 20px;
}

.feature .icon { font-size: 26px; }
.feature h3 { margin: 10px 0 6px; font-size: 17px; }
.feature p { margin: 0; color: var(--muted); font-size: 15px; }

/* Content sections */
.card {
    background: var(--bg-soft);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 8px 24px;
    margin: 24px 0;
}

h2 { font-size: 22px; letter-spacing: -0.01em; margin-top: 32px; }
h3 { font-size: 18px; }

a { color: var(--brand-blue); }

hr { border: none; border-top: 1px solid var(--line); margin: 32px 0; }

code {
    background: var(--bg-soft);
    border: 1px solid var(--line);
    border-radius: 5px;
    padding: 1px 6px;
    font-size: 0.9em;
}

.doc-date { color: var(--muted); font-size: 15px; }

.back-link { display: inline-block; margin-top: 24px; font-weight: 500; }

/* Footer */
.site-footer {
    border-top: 1px solid var(--line);
    padding: 32px 22px;
    text-align: center;
    color: var(--muted);
    font-size: 14px;
}

.site-footer .links { margin-bottom: 12px; display: flex; gap: 18px; justify-content: center; flex-wrap: wrap; }
.site-footer a { color: var(--muted); text-decoration: none; }
.site-footer a:hover { color: var(--ink); }

.operator-note {
    font-size: 13px;
    color: var(--muted);
    max-width: 620px;
    margin: 12px auto 0;
    line-height: 1.5;
}

/* Bilingual visibility */
[data-lang] { display: none; }
[data-lang].active { display: block; }
span[data-lang].active, a[data-lang].active { display: inline; }