/*!
 * Free Tools Directory - Main Styles
 * 免费在线工具箱 - CSS样式表
 * Version: 1.0.0
 */

/* ============================================
   CSS Variables - CSS变量定义
   ============================================ */
:root {
    /* Colors - 颜色变量 */
    --color-primary: #2563eb;
    --color-primary-dark: #1d4ed8;
    --color-primary-light: #3b82f6;
    --color-secondary: #7c3aed;
    --color-accent: #f59e0b;

    /* Neutral Colors - 中性色 */
    --color-text: #1f2937;
    --color-text-light: #6b7280;
    --color-text-lighter: #9ca3af;
    --color-bg: #ffffff;
    --color-bg-secondary: #f9fafb;
    --color-bg-tertiary: #f3f4f6;
    --color-border: #e5e7eb;
    --color-border-light: #f3f4f6;

    /* Semantic Colors - 语义色 */
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-error: #ef4444;
    --color-info: #3b82f6;

    /* Shadows - 阴影 */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

    /* Border Radius - 圆角 */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;

    /* Spacing - 间距 */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;

    /* Typography - 字体 */
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

    /* Transitions - 过渡 */
    --transition-fast: 150ms ease;
    --transition-base: 300ms ease;
    --transition-slow: 500ms ease;

    /* Z-index - 层级 */
    --z-dropdown: 100;
    --z-sticky: 200;
    --z-fixed: 300;
    --z-modal: 400;
    --z-tooltip: 500;
}

/* ============================================
   Reset & Base Styles - 重置与基础样式
   ============================================ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-sans);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Accessibility - 无障碍访问 */
.skip-link {
    position: absolute;
    top: -100%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--color-primary);
    color: white;
    padding: var(--space-3) var(--space-6);
    border-radius: var(--radius-md);
    z-index: var(--z-tooltip);
    transition: top var(--transition-fast);
}

.skip-link:focus {
    top: var(--space-4);
}

/* Links - 链接 */
a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

/* Lists - 列表 */
ul, ol {
    list-style: none;
}

/* Images - 图片 */
img, svg {
    display: block;
    max-width: 100%;
    height: auto;
}

/* Buttons - 按钮 */
button {
    font-family: inherit;
    font-size: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

/* Inputs - 输入框 */
input, textarea, select {
    font-family: inherit;
    font-size: inherit;
}

/* ============================================
   Container - 容器
   ============================================ */
.container {
    width: 100%;
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--space-4);
}

/* ============================================
   Header - 页头
   ============================================ */
.site-header {
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    z-index: var(--z-sticky);
    padding: var(--space-4) 0;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-4);
}

.logo a {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    color: var(--color-text);
    text-decoration: none;
}

.logo-icon {
    width: 32px;
    height: 32px;
    color: var(--color-primary);
}

.logo-text {
    font-size: 1.25rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-3);
}

.search-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-lg);
    color: var(--color-text-light);
    transition: all var(--transition-fast);
}

.search-toggle:hover {
    background: var(--color-bg-tertiary);
    color: var(--color-text);
}

.search-toggle svg {
    width: 20px;
    height: 20px;
}

/* Search Overlay - 搜索覆盖层 */
.search-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: var(--z-modal);
    display: none;
    align-items: flex-start;
    justify-content: center;
    padding: var(--space-16) var(--space-4);
}

.search-overlay.active {
    display: flex;
}

.search-container {
    width: 100%;
    max-width: 600px;
    background: var(--color-bg);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    overflow: hidden;
}

.search-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-4) var(--space-6);
    border-bottom: 1px solid var(--color-border);
}

.search-header h2 {
    font-size: 1.125rem;
    font-weight: 600;
}

.search-close {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border-radius: var(--radius-md);
    color: var(--color-text-light);
    transition: all var(--transition-fast);
}

.search-close:hover {
    background: var(--color-bg-tertiary);
    color: var(--color-text);
}

.search-close svg {
    width: 20px;
    height: 20px;
}

.search-input-wrapper {
    padding: var(--space-4) var(--space-6);
}

.search-input-wrapper input {
    width: 100%;
    padding: var(--space-3) var(--space-4);
    font-size: 1.125rem;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    outline: none;
    transition: border-color var(--transition-fast);
}

.search-input-wrapper input:focus {
    border-color: var(--color-primary);
}

.search-results {
    max-height: 400px;
    overflow-y: auto;
    padding: var(--space-4);
}

/* ============================================
   Hero Section - 英雄区域
   ============================================ */
.hero {
    background: linear-gradient(135deg, var(--color-bg-secondary) 0%, var(--color-bg) 100%);
    padding: var(--space-16) 0;
    text-align: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.hero-title {
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: var(--space-6);
    color: var(--color-text);
}

.hero-title .emoji {
    display: inline-block;
    margin: 0 var(--space-2);
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--color-text-light);
    margin-bottom: var(--space-8);
    line-height: 1.8;
}

.hero-subtitle strong {
    color: var(--color-primary);
    font-weight: 700;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: var(--space-8);
    flex-wrap: wrap;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-1);
}

.stat-number {
    font-size: 2rem;
    font-weight: 800;
    color: var(--color-primary);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--color-text-light);
}

/* ============================================
   Category Navigation - 分类导航
   ============================================ */
.category-nav {
    margin: var(--space-8) 0;
    overflow: hidden;
}

.category-scroll {
    display: flex;
    gap: var(--space-3);
    overflow-x: auto;
    padding: var(--space-2);
    scrollbar-width: none;
    -ms-overflow-style: none;
}

.category-scroll::-webkit-scrollbar {
    display: none;
}

.category-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-4) var(--space-6);
    background: var(--color-bg);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-xl);
    white-space: nowrap;
    transition: all var(--transition-fast);
    text-decoration: none;
}

.category-btn:hover {
    border-color: var(--color-primary);
    text-decoration: none;
}

.category-btn.active {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: white;
}

.category-icon {
    font-size: 1.5rem;
}

.category-name {
    font-size: 0.875rem;
    font-weight: 600;
}

.category-count {
    font-size: 0.75rem;
    padding: var(--space-1) var(--space-2);
    background: var(--color-bg-tertiary);
    border-radius: var(--radius-full);
}

.category-btn.active .category-count {
    background: rgba(255, 255, 255, 0.2);
}

/* ============================================
   Tools Section - 工具区域
   ============================================ */
.tools-section {
    padding: var(--space-8) 0;
}

.section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--space-6);
    flex-wrap: wrap;
    gap: var(--space-4);
}

.section-title {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    font-size: 1.5rem;
    font-weight: 700;
}

.title-icon {
    font-size: 1.75rem;
}

.view-options {
    display: flex;
    gap: var(--space-2);
}

.view-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    color: var(--color-text-light);
    transition: all var(--transition-fast);
}

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

.view-btn.active {
    background: var(--color-primary);
    color: white;
}

.view-btn svg {
    width: 20px;
    height: 20px;
}

/* Tools Grid - 工具网格 */
.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--space-6);
}

.tools-grid.list-view {
    grid-template-columns: 1fr;
}

.tools-grid.list-view .tool-card {
    flex-direction: row;
    align-items: center;
}

/* Tool Card - 工具卡片 */
.tool-card {
    display: flex;
    flex-direction: column;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    overflow: hidden;
    transition: all var(--transition-base);
}

.tool-card:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.tool-card-link {
    display: flex;
    flex-direction: column;
    flex: 1;
    padding: var(--space-6);
    text-decoration: none;
    color: inherit;
}

.tool-card-link:hover {
    text-decoration: none;
}

.tool-card-icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--color-primary-light), var(--color-primary));
    border-radius: var(--radius-lg);
    margin-bottom: var(--space-4);
    font-size: 1.5rem;
}

.tool-card-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--space-2);
    color: var(--color-text);
}

.tool-card-desc {
    font-size: 0.875rem;
    color: var(--color-text-light);
    line-height: 1.6;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.tool-card-meta {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    margin-top: var(--space-4);
    padding-top: var(--space-4);
    border-top: 1px solid var(--color-border-light);
}

.tool-card-category {
    font-size: 0.75rem;
    padding: var(--space-1) var(--space-2);
    background: var(--color-bg-tertiary);
    border-radius: var(--radius-full);
    color: var(--color-text-light);
}

.tool-card-action {
    margin-left: auto;
    display: flex;
    align-items: center;
    gap: var(--space-1);
    font-size: 0.875rem;
    color: var(--color-primary);
    font-weight: 500;
}

/* Load More - 加载更多 */
.load-more {
    display: flex;
    justify-content: center;
    margin-top: var(--space-10);
}

.btn-load-more {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-4) var(--space-8);
    background: var(--color-bg);
    border: 2px solid var(--color-primary);
    border-radius: var(--radius-full);
    color: var(--color-primary);
    font-weight: 600;
    transition: all var(--transition-fast);
}

.btn-load-more:hover {
    background: var(--color-primary);
    color: white;
}

.btn-load-more svg {
    width: 20px;
    height: 20px;
}

/* ============================================
   Footer - 页脚
   ============================================ */
.site-footer {
    background: var(--color-bg-secondary);
    border-top: 1px solid var(--color-border);
    padding: var(--space-16) 0 var(--space-8);
    margin-top: var(--space-16);
}

.footer-content {
    display: flex;
    flex-direction: column;
    gap: var(--space-10);
}

.footer-main {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: var(--space-10);
}

@media (max-width: 768px) {
    .footer-main {
        grid-template-columns: 1fr;
    }
}

.footer-brand {
    max-width: 300px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    margin-bottom: var(--space-4);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-text);
}

.footer-logo .logo-icon {
    width: 28px;
    height: 28px;
    color: var(--color-primary);
}

.footer-desc {
    font-size: 0.875rem;
    color: var(--color-text-light);
    line-height: 1.8;
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-8);
}

@media (max-width: 768px) {
    .footer-links {
        grid-template-columns: repeat(2, 1fr);
    }
}

.footer-column h3 {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--space-4);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.footer-column ul {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.footer-column a {
    font-size: 0.875rem;
    color: var(--color-text-light);
    transition: color var(--transition-fast);
}

.footer-column a:hover {
    color: var(--color-primary);
}

.footer-bottom {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: var(--space-8);
    border-top: 1px solid var(--color-border);
    flex-wrap: wrap;
    gap: var(--space-4);
}

.copyright,
.source-info {
    font-size: 0.875rem;
    color: var(--color-text-light);
}

/* ============================================
   Responsive - 响应式设计
   ============================================ */
@media (max-width: 640px) {
    .hero {
        padding: var(--space-10) 0;
    }

    .hero-title {
        font-size: 1.75rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .hero-stats {
        gap: var(--space-6);
    }

    .stat-number {
        font-size: 1.5rem;
    }

    .tools-grid {
        grid-template-columns: 1fr;
    }

    .category-btn {
        padding: var(--space-3) var(--space-4);
    }

    .category-name {
        font-size: 0.75rem;
    }
}

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

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

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

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

.hidden {
    display: none !important;
}

.visible {
    display: block !important;
}

/* Animation - 动画 */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.animate-fadeIn {
    animation: fadeIn var(--transition-base) ease forwards;
}

@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.animate-pulse {
    animation: pulse 2s ease-in-out infinite;
}

/* Loading Skeleton - 加载骨架屏 */
.skeleton {
    background: linear-gradient(90deg, var(--color-bg-tertiary) 25%, var(--color-bg-secondary) 50%, var(--color-bg-tertiary) 75%);
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s ease-in-out infinite;
    border-radius: var(--radius-md);
}

@keyframes skeleton-loading {
    0% {
        background-position: 200% 0;
    }
    100% {
        background-position: -200% 0;
    }
}

.skeleton-card {
    height: 200px;
    border-radius: var(--radius-xl);
}