:root {
    --bg: #f5f7fa;
    --card: #ffffff;
    --primary: #3b82f6;
    --primary-dark: #2563eb;
    --text: #1f2937;
    --muted: #6b7280;
    --border: #e5e7eb;
}

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

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

.wrap { max-width: 760px; margin: 0 auto; padding: 0 16px; }

.site-header {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #fff;
    padding: 40px 0;
    text-align: center;
}
.site-header h1 { font-size: 2rem; }
.subtitle { opacity: .9; margin-top: 6px; }

.header-flex {
    display: flex;
    align-items: center;
    justify-content: space-between;
    text-align: left;
}
.top-nav a {
    display: inline-block;
    background: rgba(255,255,255,.2);
    color: #fff;
    padding: 8px 16px;
    border-radius: 8px;
    text-decoration: none;
    font-size: .95rem;
    transition: background .2s;
}
.top-nav a:hover { background: rgba(255,255,255,.35); }

@media (max-width: 520px) {
    .header-flex { flex-direction: column; gap: 12px; text-align: center; }
}

main { padding: 28px 0; }

.card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 28px;
    box-shadow: 0 1px 3px rgba(0,0,0,.06);
}
.card h2 { margin-bottom: 14px; font-size: 1.2rem; }

form label {
    display: block;
    font-size: .9rem;
    color: var(--muted);
    margin-bottom: 12px;
}
form input, form textarea {
    width: 100%;
    margin-top: 6px;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font: inherit;
    color: var(--text);
    background: #fff;
}
form input:focus, form textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(59,130,246,.15);
}
form button {
    background: var(--primary);
    color: #fff;
    border: none;
    padding: 10px 22px;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    transition: background .2s;
}
form button:hover { background: var(--primary-dark); }

.alert {
    padding: 12px 16px;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: .95rem;
}
.alert-success { background: #ecfdf5; color: #047857; border: 1px solid #a7f3d0; }
.alert-error   { background: #fef2f2; color: #b91c1c; border: 1px solid #fecaca; }

.post-list { list-style: none; }
.post-item {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 16px 18px;
    margin-bottom: 14px;
    box-shadow: 0 1px 3px rgba(0,0,0,.06);
}
.post-item h3 { font-size: 1.1rem; }
.post-meta { color: var(--muted); font-size: .82rem; margin: 4px 0 8px; }
.post-content { white-space: pre-wrap; }

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

.site-footer {
    text-align: center;
    color: var(--muted);
    font-size: .85rem;
    padding: 24px 0;
    border-top: 1px solid var(--border);
}