/* ============================================
   CSS 变量定义
   ============================================ */
:root {
    /* 主色调 */
    --color-primary: #2563EB;
    --color-primary-hover: #1D4ED8;
    --color-primary-light: #DBEAFE;

    /* 中性色 */
    --color-bg: #FFFFFF;
    --color-bg-secondary: #F8FAFC;
    --color-bg-tertiary: #F1F5F9;
    --color-border: #E2E8F0;
    --color-border-hover: #CBD5E1;

    /* 文字颜色 */
    --color-text-primary: #0F172A;
    --color-text-secondary: #475569;
    --color-text-tertiary: #94A3B8;

    /* 功能色 */
    --color-success: #10B981;
    --color-success-bg: #D1FAE5;
    --color-warning: #F59E0B;
    --color-warning-bg: #FEF3C7;
    --color-error: #EF4444;
    --color-error-bg: #FEE2E2;
    --color-info: #3B82F6;
    --color-info-bg: #DBEAFE;

    /* 阴影 */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);

    /* 间距 */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* 圆角 */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;

    /* 过渡 */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
}

/* ============================================
   全局样式重置
   ============================================ */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

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

/* ============================================
   容器
   ============================================ */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* ============================================
   头部导航
   ============================================ */
.header {
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-text-primary);
    text-decoration: none;
}

.logo-icon {
    width: 28px;
    height: 28px;
}

.nav {
    display: flex;
    gap: var(--spacing-lg);
    align-items: center;
}

.nav-link {
    color: var(--color-text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition-fast);
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-primary);
    transition: width var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-primary);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

.lang-switcher {
    display: flex;
    align-items: center;
}

.lang-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 32px;
    padding: 0 var(--spacing-sm);
    font-size: 0.75rem;
    font-weight: 600;
    background-color: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.lang-btn:hover {
    background-color: var(--color-border);
    border-color: var(--color-border-hover);
}

.lang-btn:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.lang-btn span {
    user-select: none;
}

/* ============================================
   面包屑导航
   ============================================ */
.breadcrumb {
    margin: var(--spacing-lg) 0;
}

.breadcrumb ol {
    display: flex;
    list-style: none;
    gap: var(--spacing-sm);
    font-size: 0.875rem;
}

.breadcrumb li:not(:last-child)::after {
    content: '/';
    color: var(--color-text-tertiary);
    margin-left: var(--spacing-sm);
}

.breadcrumb a {
    color: var(--color-text-secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

.breadcrumb span {
    color: var(--color-text-tertiary);
}

/* ============================================
   工具切换导航
   ============================================ */
.tools-tab {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-sm);
    background-color: var(--color-bg-tertiary);
    border-radius: var(--radius-lg);
    overflow-x: auto;
}

.tab-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    background-color: transparent;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
    font-family: inherit;
    text-decoration: none;
}

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

.tab-btn.active {
    background-color: var(--color-bg);
    color: var(--color-primary);
    font-weight: 600;
    box-shadow: var(--shadow-sm);
}

.tab-btn:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.tab-btn svg {
    flex-shrink: 0;
}

/* ============================================
   主要内容区
   ============================================ */
.main {
    padding: var(--spacing-xl) 0;
}

/* ============================================
   功能说明
   ============================================ */

/* ============================================
   当前时间显示
   ============================================ */
.current-time-section {
    margin-bottom: var(--spacing-2xl);
}

.current-time-card {
    background-color: var(--color-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    padding: var(--spacing-xl);
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.current-time-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
}

.time-display {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
}

.time-value {
    font-size: 4rem;
    font-weight: 700;
    font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', 'Monaco', monospace;
    color: var(--color-primary);
    line-height: 1;
}

.date-value {
    font-size: 1.5rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', 'Monaco', monospace;
}

.timezone-info {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.timezone-info label {
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text-secondary);
}

.timezone-select {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text-primary);
    background-color: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: inherit;
}

.timezone-select:hover {
    border-color: var(--color-border-hover);
}

.timezone-select:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.timestamp-info {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
    background-color: var(--color-bg-tertiary);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
}

.timestamp-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-md);
}

.timestamp-label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-secondary);
}

.timestamp-value {
    font-size: 0.9375rem;
    font-weight: 600;
    font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', 'Monaco', monospace;
    color: var(--color-text-primary);
}

/* ============================================
   转换区域
   ============================================ */
.converter-section {
    margin-bottom: var(--spacing-2xl);
}

.converter-section .section-title {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-lg);
    text-align: left;
}

.converter-box {
    background-color: var(--color-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    padding: var(--spacing-xl);
}

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

.input-group label {
    display: block;
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-sm);
}

.converter-input,
.timezone-select,
.unit-select {
    width: 100%;
    padding: var(--spacing-md);
    font-size: 1rem;
    font-weight: 500;
    color: var(--color-text-primary);
    background-color: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    font-family: inherit;
}

.converter-input:hover,
.timezone-select:hover,
.unit-select:hover {
    border-color: var(--color-border-hover);
}

.converter-input:focus,
.timezone-select:focus,
.unit-select:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.input-with-unit {
    display: flex;
    gap: var(--spacing-sm);
}

.input-with-unit .converter-input {
    flex: 1;
}

.input-with-unit .unit-select {
    width: auto;
    min-width: 140px;
}

.converter-actions {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.converter-actions .btn {
    flex: 1;
    justify-content: center;
}

.result-display {
    background-color: var(--color-bg-tertiary);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
}

.result-display label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-sm);
}

.result-value {
    font-size: 1.125rem;
    font-weight: 600;
    font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', 'Monaco', monospace;
    color: var(--color-text-primary);
    word-break: break-all;
}

/* ============================================
   功能说明
   ============================================ */
.intro-section {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.page-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text-primary);
}

.page-description {
    font-size: 1.125rem;
    color: var(--color-text-secondary);
}

/* ============================================
   工具栏
   ============================================ */
.toolbar {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md);
    background-color: var(--color-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.875rem;
    font-weight: 500;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: inherit;
}

.btn:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

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

.btn-primary:hover:not(:disabled) {
    background-color: var(--color-primary-hover);
}

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

.btn-secondary:hover:not(:disabled) {
    background-color: var(--color-border);
}

.btn-info {
    background-color: var(--color-info);
    color: white;
}

.btn-info:hover:not(:disabled) {
    background-color: var(--color-primary-hover);
}

.btn-danger {
    background-color: var(--color-error);
    color: white;
}

.btn-danger:hover:not(:disabled) {
    background-color: #DC2626;
}

.btn-success {
    background-color: var(--color-success);
    color: white;
}

.btn-success:hover:not(:disabled) {
    background-color: #059669;
}

.toolbar-divider {
    width: 1px;
    background-color: var(--color-border);
    margin: 0 var(--spacing-sm);
}

.checkbox-label {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    cursor: pointer;
    user-select: none;
}

.checkbox-label input[type="checkbox"] {
    width: 16px;
    height: 16px;
    cursor: pointer;
    accent-color: var(--color-primary);
}

.checkbox-label:hover {
    color: var(--color-text-primary);
}

/* ============================================
   编辑器区域
   ============================================ */
.editor-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

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

.editor-panel {
    background-color: var(--color-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    overflow: hidden;
}

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

.editor-header h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--color-text-primary);
}

.status-badge {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: var(--radius-sm);
    background-color: var(--color-info-bg);
    color: var(--color-info);
}

.status-badge.success {
    background-color: var(--color-success-bg);
    color: var(--color-success);
}

.status-badge.error {
    background-color: var(--color-error-bg);
    color: var(--color-error);
}

.json-editor {
    width: 100%;
    min-height: 400px;
    padding: var(--spacing-lg);
    font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', 'Monaco', monospace;
    font-size: 0.875rem;
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-bg);
    border: none;
    resize: vertical;
    outline: none;
}

.json-editor::placeholder {
    color: var(--color-text-tertiary);
}

/* ============================================
   JSON 高亮样式
   ============================================ */
.json-output-highlighted {
    overflow-x: auto;
    white-space: pre-wrap;
    word-wrap: break-word;
}

.json-output-highlighted .json-key {
    color: #2563EB; /* 蓝色 */
}

.json-output-highlighted .json-string {
    color: #10B981; /* 绿色 */
}

.json-output-highlighted .json-number {
    color: #F59E0B;
}

.json-output-highlighted .json-boolean {
    color: #8B5CF6;
}

.json-output-highlighted .json-null {
    color: #6B7280;
}

/* ============================================
   状态消息
   ============================================ */
.status-message {
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-md);
    display: none;
}

.status-message.show {
    display: block;
    animation: slideDown var(--transition-base);
}

.status-message.success {
    background-color: var(--color-success-bg);
    color: var(--color-success);
    border-left: 4px solid var(--color-success);
}

.status-message.error {
    background-color: var(--color-error-bg);
    color: var(--color-error);
    border-left: 4px solid var(--color-error);
}

.status-message.info {
    background-color: var(--color-info-bg);
    color: var(--color-info);
    border-left: 4px solid var(--color-info);
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ============================================
   功能特点
   ============================================ */
.features-section {
    margin-bottom: var(--spacing-2xl);
}

.section-title {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xl);
    text-align: center;
    color: var(--color-text-primary);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.feature-card {
    background-color: var(--color-bg);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    width: 64px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--color-primary-light);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-md);
}

.feature-card h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text-primary);
}

.feature-card p {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
}

/* ============================================
   使用说明
   ============================================ */
.usage-section {
    background-color: var(--color-bg);
    padding: var(--spacing-2xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    margin-bottom: var(--spacing-2xl);
}

.usage-list {
    padding-left: var(--spacing-xl);
    font-size: 1rem;
    color: var(--color-text-secondary);
}

.usage-list li {
    margin-bottom: var(--spacing-md);
}

.usage-list ul {
    padding-left: var(--spacing-lg);
    margin-top: var(--spacing-sm);
}

.usage-list li li {
    margin-bottom: var(--spacing-sm);
}

/* ============================================
   页脚
   ============================================ */
.footer {
    background-color: var(--color-bg);
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.footer-section h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: var(--color-text-primary);
}

.footer-section p {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--spacing-sm);
}

.footer-links a {
    color: var(--color-text-secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
}

.footer-bottom p {
    font-size: 0.875rem;
    color: var(--color-text-tertiary);
}

/* ============================================
   响应式设计
   ============================================ */
@media (max-width: 768px) {
    .header .container {
        flex-direction: column;
        gap: var(--spacing-md);
    }

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

    .tools-tab {
        flex-wrap: nowrap;
        justify-content: flex-start;
        padding: var(--spacing-sm);
    }

    .tab-btn {
        padding: var(--spacing-sm) var(--spacing-md);
        font-size: 0.875rem;
    }

    .time-value {
        font-size: 3rem;
    }

    .date-value {
        font-size: 1.25rem;
    }

    .timestamp-info {
        grid-template-columns: 1fr;
    }

    .timestamp-row {
        flex-direction: column;
        align-items: flex-start;
    }

    .converter-actions {
        flex-direction: column;
    }

    .page-title {
        font-size: 1.5rem;
    }

    .page-description {
        font-size: 1rem;
    }

    .toolbar {
        justify-content: center;
    }

    .section-title {
        font-size: 1.5rem;
    }

    .usage-section {
        padding: var(--spacing-lg);
    }
}

/* ============================================
   无障碍增强
   ============================================ */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* 焦点可见性 */
button:focus-visible,
a:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* 高对比度模式支持 */
@media (prefers-contrast: high) {
    :root {
        --color-border: #000000;
        --color-text-tertiary: #333333;
    }
}
/* ============================================
   Text Statistics
   ============================================ */
.stats-display {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
    background-color: var(--color-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    padding: var(--spacing-lg);
}

.stats-row {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-md);
    background-color: var(--color-bg-tertiary);
    border-radius: var(--radius-md);
    min-width: 100px;
}

.stats-label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-secondary);
}

.stats-value {
    font-size: 1.5rem;
    font-weight: 600;
    font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', 'Monaco', monospace;
    color: var(--color-primary);
}

/* ============================================
   响应式设计 - Case Converter
   ============================================ */
@media (max-width: 768px) {
    .stats-display {
        flex-wrap: wrap;
        justify-content: center;
    }

    .stats-row {
        min-width: 80px;
        padding: var(--spacing-sm);
    }

    .stats-value {
        font-size: 1.25rem;
    }
}