/* ========================================
   CodeLearn - 全局样式
   ======================================== */

/* CSS 变量 */
:root {
    /* 颜色主题 - 深色模式 */
    --bg-primary: #1a1a2e;
    --bg-secondary: #16213e;
    --bg-tertiary: #0f3460;
    --bg-card: #252542;
    
    --text-primary: #eaeaea;
    --text-secondary: #a0a0a0;
    --text-muted: #6c6c6c;
    
    --accent-primary: #667eea;
    --accent-secondary: #764ba2;
    --accent-success: #4ade80;
    --accent-warning: #fbbf24;
    --accent-danger: #f87171;
    
    --border-color: #2d2d44;
    
    /* 尺寸 */
    --header-height: 60px;
    --footer-height: 60px;
    --sidebar-width: 300px;
    
    /* 间距 */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    
    /* 圆角 */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    
    /* 阴影 */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
    
    /* 过渡 */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.25s ease;
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

a {
    color: var(--accent-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--accent-secondary);
}

/* 按钮样式 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: 10px 20px;
    font-size: 14px;
    font-weight: 500;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    color: white;
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover:not(:disabled) {
    background: var(--bg-card);
}

.btn-text {
    background: transparent;
    color: var(--text-secondary);
    padding: var(--spacing-sm) var(--spacing-md);
}

.btn-text:hover {
    color: var(--text-primary);
    background: var(--bg-secondary);
}

.btn-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    background: transparent;
    border: none;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: 18px;
}

.btn-icon:hover {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

/* 图标 */
.icon {
    display: inline-block;
    font-style: normal;
    line-height: 1;
}

/* 进度条 */
.progress-bar {
    width: 100%;
    height: 4px;
    background: var(--bg-tertiary);
    border-radius: 2px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    transition: width var(--transition-normal);
}

/* 模态框 */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    z-index: 1000;
    flex-direction: column;
}

.modal.active {
    display: flex;
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
    font-size: 18px;
    font-weight: 600;
}

.modal-body {
    flex: 1;
    padding: var(--spacing-md);
    overflow: hidden;
}

/* 侧边栏 */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: var(--sidebar-width);
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    z-index: 1001;
    transform: translateX(-100%);
    transition: transform var(--transition-normal);
    display: flex;
    flex-direction: column;
}

.sidebar.active {
    transform: translateX(0);
}

.sidebar-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
}

.sidebar-header h3 {
    font-size: 18px;
    font-weight: 600;
}

.sidebar-content {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-md);
}

.sidebar-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-fast);
}

.sidebar-overlay.active {
    opacity: 1;
    visibility: visible;
}

/* 滚动条样式 */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--bg-tertiary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--border-color);
}

/* 选中文字样式 */
::selection {
    background: var(--accent-primary);
    color: white;
}