:root {
    --page-bg: #f1f5f9;
    --header-bg: #0f172a;
    --panel: #ffffff;
    --text: #1e293b;
    --muted: #64748b;
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --danger-bg: #fef2f2;
    --danger-text: #b91c1c;
    --border: #e2e8f0;
    --code-bg: #eef2ff;
    --nav-link: #cbd5e1;
    --nav-link-hover: #ffffff;
    --nav-user: #94a3b8;
    --header-text: #ffffff;
}

html[data-theme="dark"] {
    --page-bg: #0b1220;
    --header-bg: #111a2c;
    --panel: #111827;
    --text: #e5e7eb;
    --muted: #94a3b8;
    --primary: #3b82f6;
    --primary-dark: #2563eb;
    --danger-bg: #450a0a;
    --danger-text: #fca5a5;
    --border: #1f2937;
    --code-bg: #1f2937;
    --nav-link: #cbd5e1;
    --nav-link-hover: #ffffff;
    --nav-user: #94a3b8;
    --header-text: #ffffff;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    color: var(--text);
    background: var(--page-bg);
    line-height: 1.6;
}

.container {
    width: 100%;
    max-width: 960px;
    margin: 0 auto;
    padding: 0 20px;
}

.site-header {
    background: var(--header-bg);
    color: var(--header-text);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 60px;
}

.brand {
    font-size: 20px;
    font-weight: 700;
    color: var(--header-text);
    text-decoration: none;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 16px;
}

.nav-links a {
    color: var(--nav-link);
    text-decoration: none;
}

.nav-links a:hover { color: var(--nav-link-hover); }

.nav-user { color: var(--nav-user); font-size: 14px; }

.btn {
    display: inline-block;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: 8px;
    padding: 10px 18px;
    font-size: 15px;
    cursor: pointer;
    text-decoration: none;
    transition: background .2s;
}

.btn:hover { background: var(--primary-dark); }

.btn-sm { padding: 6px 12px; font-size: 13px; }

.theme-toggle {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--nav-link);
    border-radius: 8px;
    padding: 6px 12px;
    font-size: 13px;
    cursor: pointer;
    line-height: 1;
}

.theme-toggle:hover {
    color: var(--nav-link-hover);
    border-color: var(--nav-link-hover);
}

.btn-block { width: 100%; margin-top: 8px; }

.hero {
    text-align: center;
    padding: 64px 0 32px;
}

.hero h1 { font-size: 34px; margin: 0 0 12px; }

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 20px;
    padding: 24px 0 48px;
}

.card {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 22px;
}

.card h3 { margin-top: 0; }

.card code {
    background: var(--code-bg);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 13px;
}

.auth-card {
    max-width: 380px;
    margin: 56px auto;
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 28px;
}

.auth-card h1 { margin: 0 0 4px; font-size: 24px; }

.demo-box {
    background: var(--code-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 10px 14px;
    margin: 14px 0;
    font-size: 14px;
}

.demo-title {
    margin: 0 0 6px;
    font-weight: 600;
    color: var(--text);
}

.demo-box code {
    background: var(--panel);
    padding: 2px 6px;
    border-radius: 4px;
}

.auth-card label {
    display: block;
    margin: 14px 0 6px;
    font-size: 14px;
    font-weight: 600;
}

.auth-card input {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 15px;
}

.auth-card input:focus {
    outline: none;
    border-color: var(--primary);
}

.form-hint {
    margin-top: 16px;
    text-align: center;
    font-size: 14px;
    color: var(--muted);
}

.form-hint a {
    color: var(--primary);
    text-decoration: none;
}

.form-hint a:hover {
    text-decoration: underline;
}

.muted { color: var(--muted); }

.alert {
    border-radius: 8px;
    padding: 10px 14px;
    margin: 16px 0;
    font-size: 14px;
}

.alert-error {
    background: var(--danger-bg);
    color: var(--danger-text);
}

.dashboard { padding: 40px 0; }

.info-table {
    width: 100%;
    max-width: 480px;
    border-collapse: collapse;
    margin: 20px 0;
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
}

.info-table th,
.info-table td {
    text-align: left;
    padding: 12px 16px;
    border-bottom: 1px solid var(--border);
}

.info-table th { width: 120px; color: var(--muted); font-weight: 600; }

.site-footer {
    margin-top: 40px;
    padding: 24px 0;
    color: var(--muted);
    text-align: center;
    font-size: 13px;
}