/* ==========================================================================
   1. 基础全局变量与重置
   ========================================================================== */
:root {
    --primary-color: #0d6efd;
    --primary-hover: #0b5ed7;
    --sidebar-width: 250px;
    --header-height: 60px;
    --bg-light: #f8f9fa;
    --border-color: #dee2e6;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-light);
    min-height: 100vh;
}

/* ==========================================================================
   2. 侧边栏与主布局 (后台管理使用)
   ========================================================================== */
.sidebar {
    width: var(--sidebar-width);
    height: 100vh;
    position: fixed;
    top: 0;
    left: 0;
    background: #ffffff;
    border-right: 1px solid var(--border-color);
    z-index: 1000;
    transition: transform var(--transition-normal);
}

.sidebar-header {
    height: var(--header-height);
    display: flex;
    align-items: center;
    padding: 0 1.5rem;
    border-bottom: 1px solid var(--border-color);
    font-weight: 700;
    color: var(--primary-color);
    font-size: 1.25rem;
}

.sidebar-nav {
    padding: 1rem 0;
}

.nav-link {
    padding: 0.75rem 1.5rem;
    color: #495057;
    display: flex;
    align-items: center;
    font-weight: 500;
    transition: all var(--transition-fast);
    text-decoration: none;
}

.nav-link:hover {
    color: var(--primary-color);
    background-color: #e9ecef;
}

.nav-link.active {
    color: var(--primary-color);
    background-color: #e7f1ff;
    border-right: 3px solid var(--primary-color);
}

.nav-link i {
    margin-right: 0.75rem;
    width: 20px;
    text-align: center;
}

.main-content {
    margin-left: var(--sidebar-width);
    padding: 2rem;
    transition: margin-left var(--transition-normal);
}

.top-header {
    height: var(--header-height);
    background: #ffffff;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 2rem;
    position: sticky;
    top: 0;
    z-index: 900;
}

/* UI 组件微调 */
.layui-card {
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    border-radius: var(--radius-md);
}

.layui-card-header {
    font-weight: 600;
    border-bottom: 1px solid #f0f0f0;
}

/* ==========================================================================
   3. 登录页面重构 (核心优化)
   ========================================================================== */
.login-page {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background: radial-gradient(circle at 50% 50%, #ffffff 0%, #eef2f7 100%);
}

.login-card {
    width: 100%;
    max-width: 400px;
    padding: 2.5rem 2rem;
    background: #ffffff;
    border-radius: var(--radius-lg);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.05);
}

/* 修复 Layui 表单样式污染：登录页不需要左侧宽大的 Label 占位 */
.login-card .layui-form-item {
    position: relative;
    margin-bottom: 1.25rem;
}

.login-card .layui-input-block {
    margin-left: 0 !important; /* 强制取消默认的 110px 留白 */
}

/* 将图标作为 Input 的前缀修饰，提升现代感 */
.login-card .login-icon-prefix {
    position: absolute;
    left: 12px;
    top: 50%;
    transform: translateY(-50%);
    color: #999;
    font-size: 1.1rem;
    z-index: 10;
    pointer-events: none;
}

.login-card .layui-input {
    padding-left: 38px !important; /* 为左侧图标留出空间 */
    height: 45px;
    line-height: 45px;
    border-radius: var(--radius-md);
    border-color: #ced4da;
    transition: all var(--transition-fast);
}

.login-card .layui-input:focus {
    border-color: var(--primary-color) !important;
    box-shadow: 0 0 0 0.25rem rgba(13, 110, 253, 0.25);
}

/* 按钮与提示框优化 */
.login-card .btn-submit {
    height: 45px;
    line-height: 45px;
    background-color: var(--primary-color) !important;
    border-radius: var(--radius-md) !important;
    font-size: 1rem;
    font-weight: 600;
    transition: background-color var(--transition-fast);
}

.login-card .btn-submit:hover {
    background-color: var(--primary-hover) !important;
    opacity: 0.9;
}

.login-card .layui-alert {
    border-radius: var(--radius-md);
    padding: 12px 15px;
}

/* ==========================================================================
   4. 响应式布局断点
   ========================================================================== */
@media (max-width: 991.98px) {
    .sidebar {
        transform: translateX(-100%);
    }

    .sidebar.show {
        transform: translateX(0);
        box-shadow: 0 0 15px rgba(0, 0, 0, 0.1);
    }

    .main-content {
        margin-left: 0;
        padding: 1rem;
    }

    .top-header {
        padding: 0 1rem;
    }
    
    .login-card {
        max-width: 90%;
        padding: 2rem 1.5rem;
    }
}