/* 
 * 星雨童行 - 全局CSS变量系统
 * 统一管理所有样式变量，便于维护和扩展
 */

:root {
    /* ========== 颜色系统 ========== */
    /* 主色调 */
    --primary: #3D8BA0;
    --primary-dark: #2E7489;
    --primary-light: #5BA3BA;
    --primary-lightest: #E8EEF3;
    
    /* 背景色 */
    --bg-body: #FAF8F5;
    --bg-secondary: #F2EFE9;
    --bg-hover: #EDE8E0;
    --bg-card: #FFFFFF;
    --bg-overlay: rgba(0, 0, 0, 0.5);
    
    /* 文字颜色 */
    --text: #0D0D0D;
    --text-muted: #444444;
    --text-light: #666666;
    --text-white: #FFFFFF;
    
    /* 边框颜色 */
    --border: #D8D4CC;
    --border-light: #E8E4DD;
    --border-focus: var(--primary);
    
    /* 状态颜色 */
    --success: #6B9B70;
    --success-light: #E8F5EA;
    --warning: #D97706;
    --warning-light: #FEF3C7;
    --error: #DC2626;
    --error-light: #FEE2E2;
    --info: #3B82F6;
    --info-light: #EFF6FF;
    
    /* ========== 间距系统 ========== */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 48px;
    --spacing-3xl: 64px;
    
    /* ========== 宽度系统（移动端优先）========== */
    --width-xs: 320px;
    --width-sm: 360px;
    --width-md: 480px;
    --width-lg: 768px;
    --width-xl: 1024px;
    --width-2xl: 1200px;
    --width-max: 1400px;
    
    /* 内容宽度 */
    --content-width: 1024px;
    --content-max-width: 1200px;
    --container-padding: 16px;
    --container-max-padding: 24px;
    
    /* ========== 字体系统 ========== */
    --font-family-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Helvetica Neue', Helvetica, Arial, sans-serif;
    --font-family-mono: 'SF Mono', Monaco, 'Inconsolata', 'Roboto Mono', monospace;
    
    --font-size-xs: 14px;
    --font-size-sm: 15px;
    --font-size-base: 16px;
    --font-size-md: 17px;
    --font-size-lg: 18px;
    --font-size-xl: 20px;
    --font-size-2xl: 22px;
    --font-size-3xl: 26px;
    --font-size-4xl: 34px;
    --font-size-5xl: 42px;
    
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    --line-height-tight: 1.3;
    --line-height-normal: 1.6;
    --line-height-relaxed: 1.7;
    
    /* ========== 阴影系统 ========== */
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-xl: 0 8px 32px rgba(0, 0, 0, 0.16);
    
    /* ========== 圆角系统 ========== */
    --radius: 12px;
    --radius-sm: 8px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 9999px;
    
    /* ========== 过渡系统 ========== */
    --transition-fast: 150ms ease;
    --transition-normal: 200ms ease;
    --transition-slow: 300ms ease;
    
    /* ========== Z-index系统 ========== */
    --z-10: 10;
    --z-20: 20;
    --z-30: 30;
    --z-40: 40;
    --z-50: 50;
    --z-100: 100;
    
    /* ========== 断点系统（移动端优先）========== */
    --breakpoint-sm: 480px;
    --breakpoint-md: 640px;
    --breakpoint-lg: 768px;
    --breakpoint-xl: 1024px;
    --breakpoint-2xl: 1200px;
}

/* 响应式容器宽度 */
@media (min-width: 768px) {
    :root {
        --container-padding: 24px;
    }
}

/* 焦点样式优化 - 提高可访问性 */
:focus {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

:focus:not(:focus-visible) {
    outline: none;
}

:focus-visible {
    outline: 3px solid var(--primary);
    outline-offset: 2px;
}

button:focus-visible,
a:focus-visible,
input:focus-visible,
textarea:focus-visible,
select:focus-visible {
    outline: 3px solid var(--primary);
    outline-offset: 2px;
    box-shadow: 0 0 0 4px rgba(61, 139, 160, 0.15);
}

/* 高对比度模式 */
@media (prefers-contrast: high) {
    :focus-visible {
        outline: 3px solid #000000;
        outline-offset: 3px;
    }
    
    .dark :focus-visible {
        outline: 3px solid #FFFFFF;
    }
}

@media (min-width: 1024px) {
    :root {
        --container-padding: 32px;
    }
}

/* 基础重置 */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-family: var(--font-family-sans);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--text);
    background-color: var(--bg-body);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    scroll-behavior: smooth;
}

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

main {
    flex: 1;
}

/* 容器类 */
.container {
    max-width: var(--content-width);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

.container-xl {
    max-width: var(--content-max-width);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* 通用链接样式 */
a {
    color: var(--primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

a:focus {
    outline: 2px solid var(--border-focus);
    outline-offset: 2px;
}

/* 通用按钮样式 */
button {
    font-family: inherit;
    font-size: inherit;
    cursor: pointer;
    border: none;
    background: none;
    transition: all var(--transition-fast);
}

button:focus {
    outline: 2px solid var(--border-focus);
    outline-offset: 2px;
}

/* 图片响应式 */
img {
    max-width: 100%;
    height: auto;
}

/* 辅助类 */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

.text-center {
    text-align: center;
}

.text-right {
    text-align: right;
}

.flex {
    display: flex;
}

.flex-col {
    flex-direction: column;
}

.items-center {
    align-items: center;
}

.justify-center {
    justify-content: center;
}

.justify-between {
    justify-content: space-between;
}

.gap-xs {
    gap: var(--spacing-xs);
}

.gap-sm {
    gap: var(--spacing-sm);
}

.gap-md {
    gap: var(--spacing-md);
}

.gap-lg {
    gap: var(--spacing-lg);
}

.mb-xs {
    margin-bottom: var(--spacing-xs);
}

.mb-sm {
    margin-bottom: var(--spacing-sm);
}

.mb-md {
    margin-bottom: var(--spacing-md);
}

.mb-lg {
    margin-bottom: var(--spacing-lg);
}

.mt-xs {
    margin-top: var(--spacing-xs);
}

.mt-sm {
    margin-top: var(--spacing-sm);
}

.mt-md {
    margin-top: var(--spacing-md);
}

.mt-lg {
    margin-top: var(--spacing-lg);
}

/* ========== 二级菜单样式 ========== */

/* 桌面端导航下拉菜单 */
.nav-dropdown {
    position: relative;
    display: none; /* 默认隐藏，桌面端显示 */
}

.nav-dropdown-trigger {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 0 14px;
    height: 100%;
    font-size: 0.92rem;
    font-weight: 500;
    color: var(--text);
    background: none;
    border: none;
    cursor: pointer;
    white-space: nowrap;
    transition: color var(--transition-fast);
}

.nav-dropdown-trigger:hover {
    color: var(--primary);
}

.nav-dropdown-trigger:focus {
    outline: none;
}

.nav-dropdown-trigger.active {
    color: var(--primary);
}

.dropdown-arrow {
    font-size: 0.65rem;
    transition: transform var(--transition-fast);
}

.nav-dropdown.open .dropdown-arrow {
    transform: rotate(180deg);
}

.nav-dropdown-menu {
    position: absolute;
    top: calc(100% + 8px);
    left: 0;
    min-width: 180px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    list-style: none;
    padding: 6px 0;
    margin: 0;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: all var(--transition-normal);
    z-index: var(--z-50);
}

.nav-dropdown.open .nav-dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-link {
    display: block;
    padding: 10px 16px;
    font-size: 0.88rem;
    color: var(--text);
    text-decoration: none;
    white-space: nowrap;
    transition: background var(--transition-fast);
}

.dropdown-link:hover {
    background: var(--bg-hover);
    color: var(--primary);
}

.dropdown-link.active {
    background: var(--primary-lightest);
    color: var(--primary);
    font-weight: 600;
}

/* 移动端下拉菜单 */
.mobile-dropdown {
    border-top: 1px solid var(--border-light);
}

.mobile-dropdown-trigger {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    padding: 14px 16px;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text);
    background: none;
    border: none;
    cursor: pointer;
    text-align: left;
}

.mobile-dropdown-arrow {
    font-size: 1.2rem;
    color: var(--text-light);
    transition: transform var(--transition-fast);
    flex-shrink: 0;
}

.mobile-dropdown.open .mobile-dropdown-arrow {
    transform: rotate(90deg);
}

.mobile-dropdown-menu {
    list-style: none;
    padding: 0;
    margin: 0;
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-slow);
}

.mobile-dropdown.open .mobile-dropdown-menu {
    max-height: 200px;
}

.mobile-dropdown-link {
    display: block;
    padding: 12px 16px 12px 36px;
    font-size: 0.92rem;
    color: var(--text-muted);
    text-decoration: none;
    transition: background var(--transition-fast);
    border-bottom: 1px solid var(--border-light);
}

.mobile-dropdown-link:last-child {
    border-bottom: none;
}

.mobile-dropdown-link:hover {
    background: var(--bg-hover);
    color: var(--primary);
}

.mobile-dropdown-link.active {
    color: var(--primary);
    font-weight: 600;
    background: var(--primary-lightest);
}

/* 桌面端显示二级菜单 */
@media (min-width: 1024px) {
    .nav-dropdown {
        display: flex;
        align-items: center;
    }
}