:root {
    --color-primary: #2563eb;
    --color-bg: #f5f6fa;
    --color-text: #1f2937;
    --color-border: #e5e7eb;
    --sidebar-width: 220px;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    color: var(--color-text);
    background: var(--color-bg);
}

.site-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem 1.5rem;
    background: #fff;
    border-bottom: 1px solid var(--color-border);
}

.brand a { font-weight: 700; text-decoration: none; color: var(--color-primary); }

.user-nav a { color: var(--color-text); }
.user-nav a:hover { color: var(--color-primary); }
.user-nav form { display: inline-block; }

.layout { display: flex; min-height: calc(100vh - 110px); }

.sidebar {
    width: var(--sidebar-width);
    background: #fff;
    border-right: 1px solid var(--color-border);
    padding: 1rem 0;
}

.sidebar .nav-list { list-style: none; padding: 0; margin: 0; }
.sidebar .nav-list a {
    display: block;
    padding: 0.5rem 1.25rem;
    color: var(--color-text);
    text-decoration: none;
}
.sidebar .nav-list a:hover { background: var(--color-bg); }
.sidebar .sub-nav { list-style: none; padding-left: 1rem; margin: 0; }
.sidebar .sub-nav a { padding: 0.35rem 1rem; font-size: 0.9rem; color: #4b5563; }
.sidebar .menu-group { display: block; padding: 0.5rem 1.25rem; font-weight: 600; color: #6b7280; text-transform: uppercase; font-size: 0.75rem; }

.content { flex: 1; padding: 1.5rem; }

.site-footer { padding: 1rem; text-align: center; color: #6b7280; }

.messages { list-style: none; padding: 0; }
.alert { padding: 0.75rem 1rem; border-radius: 4px; margin-bottom: 0.5rem; }
.alert-success { background: #d1fae5; color: #065f46; }
.alert-error   { background: #fee2e2; color: #991b1b; }
.alert-warning { background: #fef3c7; color: #92400e; }
.alert-info    { background: #dbeafe; color: #1e40af; }