/* 管理端共享壳：左侧菜单 + 右侧内容 */
body {
    margin: 0;
    background: #f0f2f5;
}

.admin-shell {
    display: flex;
    min-height: 100vh;
}

.admin-sidebar {
    width: 220px;
    flex-shrink: 0;
    background: #1f2d3d;
    color: #fff;
    display: flex;
    flex-direction: column;
}

.admin-brand {
    padding: 18px 16px;
    font-size: 16px;
    font-weight: 600;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    letter-spacing: 0.5px;
}

.admin-menu {
    padding: 12px 0;
    display: flex;
    flex-direction: column;
}

.admin-menu-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 18px;
    color: rgba(255, 255, 255, 0.78);
    text-decoration: none;
    font-size: 14px;
    border-left: 3px solid transparent;
}

.admin-menu-item i {
    width: 18px;
    text-align: center;
}

.admin-menu-item:hover {
    color: #fff;
    background: rgba(255, 255, 255, 0.06);
    text-decoration: none;
}

.admin-menu-item.active {
    color: #fff;
    background: rgba(64, 158, 255, 0.18);
    border-left-color: #409eff;
}

.admin-main {
    flex: 1;
    min-width: 0;
    padding: 16px 20px 24px;
}

.admin-main .container-fluid {
    padding: 0;
}

.admin-placeholder {
    background: #fff;
    border: 1px solid #e5e7eb;
    border-radius: 8px;
    padding: 48px 24px;
    text-align: center;
    color: #6b7280;
}

@media (max-width: 900px) {
    .admin-shell {
        flex-direction: column;
    }

    .admin-sidebar {
        width: 100%;
    }

    .admin-menu {
        flex-direction: row;
        flex-wrap: wrap;
        padding: 8px;
    }

    .admin-menu-item {
        border-left: none;
        border-bottom: 2px solid transparent;
        padding: 10px 12px;
    }

    .admin-menu-item.active {
        border-bottom-color: #409eff;
    }
}