/**
 * ZeroServerTools.org - Master Stylesheet
 * Soft & Friendly Design System
 * Target: <50KB, 100/100 PageSpeed
 */

/* ============================================
   1. CSS VARIABLES & DESIGN TOKENS
   ============================================ */
:root {
    /* Color Palette - Soft & Friendly */
    --color-bg-main: #FBFBFA;          /* Warm Off-White */
    --color-bg-card: #FFFFFF;          /* Pure White */
    --color-primary: #0D9488;          /* Warm Teal */
    --color-secondary: #F97316;        /* Soft Coral */
    --color-text-dark: #27272A;        /* Dark Charcoal */
    --color-text-medium: #52525B;      /* Medium Gray */
    --color-text-light: #A1A1AA;       /* Light Gray */
    --color-border: #E4E4E7;           /* Subtle Border */
    --color-success: #10B981;          /* Success Green */
    --color-error: #EF4444;            /* Error Red */
    --color-warning: #F59E0B;          /* Warning Amber */
    
    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 0.75rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    
    /* Typography */
    --font-body: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Courier New', monospace;
    
    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
}

/* ============================================
   2. RESET & BASE STYLES
   ============================================ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-body);
    color: var(--color-text-dark);
    background-color: var(--color-bg-main);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

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

a:hover {
    color: #0A7068;
}

button {
    font-family: inherit;
    cursor: pointer;
}

/* ============================================
   3. LAYOUT CONTAINERS
   ============================================ */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

.site-main {
    flex: 1;
    padding: var(--space-2xl) 0;
}

/* ============================================
   4. SITE HEADER & NAVIGATION
   ============================================ */
.site-header {
    background: var(--color-bg-card);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.main-nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-lg) 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-text-dark);
}

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

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--space-xl);
    align-items: center;
}

.nav-menu a {
    color: var(--color-text-medium);
    font-weight: 500;
    transition: color var(--transition-fast);
}

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

.nav-dropdown {
    position: relative;
}

.nav-dropdown-toggle {
    cursor: pointer;
}

.nav-dropdown-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    min-width: 200px;
    padding: var(--space-sm);
    list-style: none;
    z-index: 100;
}

.nav-dropdown:hover .nav-dropdown-menu {
    display: block;
}

.nav-dropdown-menu li {
    margin: 0;
}

.nav-dropdown-menu a {
    display: block;
    padding: var(--space-sm);
    border-radius: var(--radius-sm);
    transition: background var(--transition-fast);
}

.nav-dropdown-menu a:hover {
    background: var(--color-bg-main);
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--color-text-dark);
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: block;
    }
}

/* ============================================
   5. HERO SECTION
   ============================================ */
.hero {
    text-align: center;
    padding: var(--space-3xl) 0;
    background: linear-gradient(135deg, #FBFBFA 0%, #F0FAF9 100%);
}

.hero h1 {
    font-size: 3rem;
    font-weight: 800;
    color: var(--color-text-dark);
    margin-bottom: var(--space-md);
    line-height: 1.2;
}

.hero p {
    font-size: 1.25rem;
    color: var(--color-text-medium);
    max-width: 600px;
    margin: 0 auto var(--space-xl);
}

.cta-button {
    display: inline-block;
    background: var(--color-primary);
    color: white;
    padding: var(--space-md) var(--space-xl);
    border-radius: var(--radius-lg);
    font-weight: 600;
    font-size: 1.125rem;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
    border: none;
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    color: white;
}

@media (max-width: 768px) {
    .hero h1 {
        font-size: 2rem;
    }
    
    .hero p {
        font-size: 1rem;
    }
}

/* ============================================
   6. TOOL GRID
   ============================================ */
.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--space-xl);
    margin: var(--space-2xl) 0;
}

.tool-card {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

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

.tool-card-icon {
    font-size: 2.5rem;
    margin-bottom: var(--space-md);
}

.tool-card h3 {
    font-size: 1.5rem;
    margin-bottom: var(--space-sm);
    color: var(--color-text-dark);
}

.tool-card p {
    color: var(--color-text-medium);
    margin-bottom: var(--space-lg);
}

.tool-card-link {
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    color: var(--color-primary);
    font-weight: 600;
}

/* ============================================
   7. TOOL PAGE LAYOUT (3-LAYER ARCHITECTURE)
   ============================================ */
.tool-page-header {
    background: var(--color-bg-card);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-2xl) 0;
    margin-bottom: var(--space-2xl);
}

.tool-page-header h1 {
    font-size: 2.5rem;
    margin-bottom: var(--space-md);
}

.tool-page-header .breadcrumb {
    color: var(--color-text-light);
    font-size: 0.875rem;
}

/* Layer 1: Interactive Tool */
.tool-container {
    background: var(--color-bg-card);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-2xl);
    margin-bottom: var(--space-2xl);
}

.drop-zone {
    border: 2px dashed var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-3xl);
    text-align: center;
    transition: all var(--transition-base);
    background: var(--color-bg-main);
}

.drop-zone.drag-over {
    border-color: var(--color-primary);
    background: #F0FAF9;
}

.drop-zone-icon {
    font-size: 3rem;
    margin-bottom: var(--space-md);
}

.btn {
    display: inline-block;
    padding: var(--space-md) var(--space-xl);
    border-radius: var(--radius-md);
    font-weight: 600;
    border: none;
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: 1rem;
}

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

.btn-primary:hover {
    background: #0A7068;
    transform: translateY(-1px);
}

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

.btn-secondary:hover {
    background: #EA580C;
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--color-primary);
    color: var(--color-primary);
}

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

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

/* Progress Bar */
.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--color-border);
    border-radius: 999px;
    overflow: hidden;
    margin: var(--space-lg) 0;
}

.progress-bar-fill {
    height: 100%;
    background: var(--color-primary);
    transition: width var(--transition-base);
}

/* Status Messages */
.status-message {
    padding: var(--space-md);
    border-radius: var(--radius-md);
    margin: var(--space-md) 0;
}

.status-success {
    background: #D1FAE5;
    color: #065F46;
    border: 1px solid var(--color-success);
}

.status-error {
    background: #FEE2E2;
    color: #991B1B;
    border: 1px solid var(--color-error);
}

.status-info {
    background: #DBEAFE;
    color: #1E40AF;
    border: 1px solid #3B82F6;
}

/* Layer 2: Educational Content */
.educational-content {
    background: var(--color-bg-card);
    border-radius: var(--radius-lg);
    padding: var(--space-2xl);
    margin-bottom: var(--space-2xl);
}

.educational-content h2 {
    font-size: 2rem;
    margin-bottom: var(--space-lg);
    color: var(--color-text-dark);
}

.educational-content h3 {
    font-size: 1.5rem;
    margin-top: var(--space-xl);
    margin-bottom: var(--space-md);
    color: var(--color-text-dark);
}

.educational-content p {
    margin-bottom: var(--space-lg);
    line-height: 1.8;
    color: var(--color-text-medium);
}

.educational-content ul, .educational-content ol {
    margin-bottom: var(--space-lg);
    padding-left: var(--space-xl);
}

.educational-content li {
    margin-bottom: var(--space-sm);
    color: var(--color-text-medium);
}

.educational-content strong {
    color: var(--color-text-dark);
}

/* Layer 3: FAQ Accordion */
.faq-section {
    background: var(--color-bg-card);
    border-radius: var(--radius-lg);
    padding: var(--space-2xl);
    margin-bottom: var(--space-2xl);
}

.faq-section h2 {
    font-size: 2rem;
    margin-bottom: var(--space-xl);
    text-align: center;
}

.faq-item {
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-lg) 0;
}

.faq-item:last-child {
    border-bottom: none;
}

.faq-question {
    width: 100%;
    text-align: left;
    background: none;
    border: none;
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text-dark);
    padding: 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-question::after {
    content: '+';
    font-size: 1.5rem;
    color: var(--color-primary);
    transition: transform var(--transition-base);
}

.faq-question.active::after {
    transform: rotate(45deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-base);
    color: var(--color-text-medium);
    padding-top: 0;
}

.faq-answer.active {
    max-height: 500px;
    padding-top: var(--space-md);
}

/* ============================================
   8. BLOG LAYOUT
   ============================================ */
.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--space-xl);
    margin: var(--space-2xl) 0;
}

.blog-card {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

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

.blog-card-meta {
    color: var(--color-text-light);
    font-size: 0.875rem;
    margin-bottom: var(--space-sm);
}

.blog-card h2 {
    font-size: 1.5rem;
    margin-bottom: var(--space-md);
}

.blog-card p {
    color: var(--color-text-medium);
    margin-bottom: var(--space-lg);
}

.blog-card-link {
    color: var(--color-primary);
    font-weight: 600;
}

/* Article Page */
.article-header {
    text-align: center;
    margin-bottom: var(--space-2xl);
}

.article-header h1 {
    font-size: 2.5rem;
    margin-bottom: var(--space-md);
}

.article-content {
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.8;
}

.article-content p {
    margin-bottom: var(--space-lg);
}

.article-content h2 {
    font-size: 2rem;
    margin-top: var(--space-2xl);
    margin-bottom: var(--space-md);
}

.article-content h3 {
    font-size: 1.5rem;
    margin-top: var(--space-xl);
    margin-bottom: var(--space-md);
}

/* ============================================
   9. FOOTER
   ============================================ */
.site-footer {
    background: var(--color-text-dark);
    color: #E4E4E7;
    padding: var(--space-3xl) 0 var(--space-xl);
    margin-top: var(--space-3xl);
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-2xl);
    margin-bottom: var(--space-2xl);
}

.footer-col h3 {
    color: white;
    margin-bottom: var(--space-md);
    font-size: 1.125rem;
}

.footer-col p {
    line-height: 1.6;
    color: #A1A1AA;
}

.footer-col ul {
    list-style: none;
}

.footer-col ul li {
    margin-bottom: var(--space-sm);
}

.footer-col a {
    color: #E4E4E7;
}

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

.footer-bottom {
    text-align: center;
    padding-top: var(--space-lg);
    border-top: 1px solid #3F3F46;
    color: #A1A1AA;
}

/* ============================================
   10. UTILITY CLASSES
   ============================================ */
.text-center { text-align: center; }
.mt-xl { margin-top: var(--space-xl); }
.mb-xl { margin-bottom: var(--space-xl); }
.hidden { display: none; }

/* ============================================
   11. RESPONSIVE DESIGN
   ============================================ */
@media (max-width: 768px) {
    .tool-grid {
        grid-template-columns: 1fr;
    }
    
    .blog-grid {
        grid-template-columns: 1fr;
    }
    
    .tool-page-header h1 {
        font-size: 1.75rem;
    }
    
    .educational-content h2 {
        font-size: 1.5rem;
    }
}

/* ============================================
   12. PRINT STYLES
   ============================================ */
@media print {
    .site-header, .site-footer, .cta-button, .btn {
        display: none;
    }
}