body {
    margin: 0;
    font-family: "Microsoft YaHei", sans-serif;
    background: #f5f7fb;
    color: #1f2937;
}

* {
    box-sizing: border-box;
}

.layout {
    display: grid;
    grid-template-columns: 250px 1fr;
    min-height: 100vh;
}

.sidebar {
    background: linear-gradient(180deg, #111827, #1f2937);
    color: #fff;
    padding: 24px;
}

.sidebar h1 {
    font-size: 22px;
    margin: 0 0 8px;
}

.nav {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 24px;
}

.nav a {
    color: #e5e7eb;
    text-decoration: none;
    padding: 10px 12px;
    border-radius: 10px;
}

.nav a:hover {
    background: rgba(255,255,255,0.08);
}

.content {
    padding: 28px;
}

.card {
    background: #fff;
    border-radius: 16px;
    padding: 24px;
    box-shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
    margin-bottom: 20px;
}

.grid {
    display: grid;
    gap: 20px;
}

.grid.two {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

h2, h3 {
    margin-top: 0;
}

label {
    display: block;
    font-weight: 600;
    margin-bottom: 8px;
}

input, textarea, select {
    width: 100%;
    padding: 12px 14px;
    border: 1px solid #d1d5db;
    border-radius: 10px;
    margin-bottom: 16px;
    font: inherit;
}

button {
    border: 0;
    background: #2563eb;
    color: #fff;
    padding: 12px 18px;
    border-radius: 10px;
    cursor: pointer;
    font: inherit;
}

button.secondary {
    background: #4b5563;
}

button.warn {
    background: #dc2626;
}

.table {
    width: 100%;
    border-collapse: collapse;
}

.table th,
.table td {
    border-bottom: 1px solid #e5e7eb;
    padding: 12px 10px;
    text-align: left;
    vertical-align: top;
}

.badge {
    display: inline-block;
    background: #dbeafe;
    color: #1d4ed8;
    padding: 4px 10px;
    border-radius: 999px;
    font-size: 12px;
}

.flash {
    padding: 12px 16px;
    border-radius: 10px;
    margin-bottom: 16px;
}

.flash.success {
    background: #dcfce7;
    color: #166534;
}

.flash.error {
    background: #fee2e2;
    color: #991b1b;
}

.muted {
    color: #6b7280;
}

.stats {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 16px;
}

.stat {
    background: #eff6ff;
    border-radius: 14px;
    padding: 18px;
}

.stat strong {
    display: block;
    font-size: 28px;
    margin-top: 8px;
}

.actions {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.login-wrap {
    max-width: 520px;
    margin: 60px auto;
}

@media (max-width: 900px) {
    .layout {
        grid-template-columns: 1fr;
    }

    .grid.two,
    .stats {
        grid-template-columns: 1fr;
    }
}