/* CSS Custom Properties - Design System */
:root {
    /* Color System */
    --primary-color: #5B6AFF;
    --secondary-color: #8C54FF;
    --accent-color: #667EEA;
    
    /* Background Colors */
    --bg-primary: #FFFFFF;
    --bg-secondary: #F5F7FA;
    --bg-card: #FFFFFF;
    --bg-hover: #F8F9FA;
    
    /* Text Colors */
    --text-primary: #333333;
    --text-secondary: #666666;
    --text-muted: #999999;
    --text-inverse: #FFFFFF;
    
    /* Border Colors */
    --border-color: #E5E7EB;
    --border-hover: #D1D5DB;
    
    /* Spacing System (8px base unit) */
    --space-xs: 8px;
    --space-sm: 16px;
    --space-md: 24px;
    --space-lg: 32px;
    --space-xl: 48px;
    
    /* Design Tokens */
    --border-radius: 12px;
    --border-radius-sm: 8px;
    --border-radius-lg: 16px;
    --shadow-card: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-hover: 0 8px 24px rgba(0, 0, 0, 0.12);
    --transition: 0.3s ease;
    --transition-fast: 0.15s ease;
    
    /* Layout */
    --header-height: 60px;
    --sidebar-width: 240px;
    --sidebar-collapsed-width: 60px;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
    --font-size-xs: 12px;
    --font-size-sm: 14px;
    --font-size-base: 16px;
    --font-size-lg: 18px;
    --font-size-xl: 20px;
    --font-size-2xl: 24px;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
}

/* Dark Theme */
[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-card: #333333;
    --bg-hover: #404040;
    
    --text-primary: #ffffff;
    --text-secondary: #cccccc;
    --text-muted: #999999;
    --text-inverse: #333333;
    
    --border-color: #404040;
    --border-hover: #525252;
    
    --shadow-card: 0 4px 12px rgba(0, 0, 0, 0.3);
    --shadow-hover: 0 8px 24px rgba(0, 0, 0, 0.4);
}

/* Reset and Base Styles */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: background-color var(--transition), color var(--transition);
}

/* Focus Management */
*:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

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

/* App Container */
.app-container {
    display: grid;
    grid-template-areas: 
        "header header"
        "sidebar main";
    grid-template-columns: var(--sidebar-width) 1fr;
    grid-template-rows: var(--header-height) 1fr;
    min-height: 100vh;
    transition: grid-template-columns var(--transition);
}

.app-container.sidebar-collapsed {
    grid-template-columns: var(--sidebar-collapsed-width) 1fr;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: var(--font-weight-semibold);
    line-height: 1.3;
    margin-bottom: var(--space-sm);
}

h1 { font-size: var(--font-size-2xl); }
h2 { font-size: var(--font-size-xl); }
h3 { font-size: var(--font-size-lg); }

p {
    margin-bottom: var(--space-sm);
}

/* Button Base Styles */
button {
    font-family: inherit;
    font-size: inherit;
    border: none;
    background: none;
    cursor: pointer;
    transition: all var(--transition-fast);
}

button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

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

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

/* Utility Classes */
.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;
}

.loading {
    opacity: 0.6;
    pointer-events: none;
}

/* Skeleton Loading Animation */
@keyframes skeleton-loading {
    0% {
        background-position: -200px 0;
    }
    100% {
        background-position: calc(200px + 100%) 0;
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.skeleton-card {
    background: linear-gradient(90deg, var(--bg-secondary) 25%, var(--bg-hover) 50%, var(--bg-secondary) 75%);
    background-size: 200px 100%;
    animation: skeleton-loading 1.5s infinite;
    border-radius: var(--border-radius);
    height: 280px;
    margin-bottom: var(--space-md);
}

/* 卡片加载动画 */
.tool-card {
    animation: fadeIn 0.5s ease-out;
}

.tool-card:nth-child(1) { animation-delay: 0.1s; }
.tool-card:nth-child(2) { animation-delay: 0.2s; }
.tool-card:nth-child(3) { animation-delay: 0.3s; }
.tool-card:nth-child(4) { animation-delay: 0.4s; }

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

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

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

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

/* Reduced Motion Support */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}