/**
 * KateHub - Tech Style Design System
 * Version: 2.0.0
 * Theme: Dark Futuristic
 */

/* ============================================
   CSS Variables - Design Tokens
   ============================================ */
:root {
    /* Colors - Cyber Theme */
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-card: #1a1a24;
    --bg-card-hover: #222230;
    
    /* Accent Colors */
    --accent-primary: #00d4ff;
    --accent-secondary: #7c3aed;
    --accent-tertiary: #10b981;
    --accent-gradient: linear-gradient(135deg, #00d4ff 0%, #7c3aed 50%, #ff006e 100%);
    --accent-glow: 0 0 20px rgba(0, 212, 255, 0.3);
    
    /* Text Colors */
    --text-primary: #f0f0f5;
    --text-secondary: #a0a0b0;
    --text-muted: #606070;
    
    /* Border & Effects */
    --border-color: rgba(255, 255, 255, 0.08);
    --border-glow: rgba(0, 212, 255, 0.3);
    --glass-bg: rgba(26, 26, 36, 0.8);
    --glass-border: rgba(255, 255, 255, 0.1);
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    
    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 48px;
    --spacing-3xl: 64px;
    
    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* ============================================
   Reset & Base
   ============================================ */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
    overflow-x: hidden;
}

/* Animated Background */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(ellipse at 20% 20%, rgba(124, 58, 237, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 80%, rgba(0, 212, 255, 0.1) 0%, transparent 50%),
        radial-gradient(ellipse at 50% 50%, rgba(16, 185, 129, 0.05) 0%, transparent 70%);
    pointer-events: none;
    z-index: -1;
}

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

a:hover {
    color: var(--text-primary);
    text-shadow: 0 0 10px var(--accent-primary);
}

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

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

.page-wrapper {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.main-content {
    flex: 1;
    padding: var(--spacing-3xl) 0;
}

/* ============================================
   Header / Navigation
   ============================================ */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--glass-border);
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
    max-width: 1200px;
    margin: 0 auto;
    padding-left: var(--spacing-lg);
    padding-right: var(--spacing-lg);
}

.logo {
    font-size: 24px;
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.5px;
    transition: var(--transition-normal);
}

.logo:hover {
    text-shadow: none;
    filter: brightness(1.2);
}

.nav-links {
    display: flex;
    gap: var(--spacing-xl);
    list-style: none;
}

.nav-links a {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 15px;
    padding: var(--spacing-sm) 0;
    position: relative;
    transition: var(--transition-normal);
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-gradient);
    transition: var(--transition-normal);
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--text-primary);
    text-shadow: none;
}

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

/* ============================================
   Hero Section
   ============================================ */
.hero {
    padding: 160px 0 100px;
    text-align: center;
    position: relative;
}

.hero-title {
    font-size: clamp(40px, 6vw, 72px);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: var(--spacing-lg);
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent-primary) 50%, var(--accent-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 20px;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto var(--spacing-2xl);
}

.hero-tags {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.tag {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    font-size: 14px;
    color: var(--text-secondary);
    transition: var(--transition-normal);
}

.tag:hover {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
    box-shadow: var(--accent-glow);
}

/* ============================================
   Cards
   ============================================ */
.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-2xl);
}

.card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: var(--transition-normal);
    position: relative;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--accent-gradient);
    opacity: 0;
    transition: var(--transition-normal);
}

.card:hover {
    transform: translateY(-4px);
    border-color: var(--border-glow);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3), var(--accent-glow);
}

.card:hover::before {
    opacity: 1;
}

.card-header {
    padding: var(--spacing-xl);
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-card) 100%);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.card-icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent-gradient);
    border-radius: var(--radius-md);
    font-size: 24px;
}

.card-body {
    padding: var(--spacing-xl);
}

.card-title {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.card-desc {
    color: var(--text-secondary);
    font-size: 15px;
    line-height: 1.6;
}

.card-meta {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border-color);
    font-size: 13px;
    color: var(--text-muted);
}

/* ============================================
   Content Pages
   ============================================ */
.page-header {
    padding: 140px 0 60px;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

.page-title {
    font-size: 42px;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.page-desc {
    color: var(--text-secondary);
    font-size: 18px;
}

.content-section {
    padding: var(--spacing-3xl) 0;
}

.section-title {
    font-size: 28px;
    font-weight: 600;
    margin-bottom: var(--spacing-xl);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.section-title::before {
    content: '';
    width: 4px;
    height: 28px;
    background: var(--accent-gradient);
    border-radius: 2px;
}

/* ============================================
   Article / Blog Post
   ============================================ */
.article {
    max-width: 800px;
    margin: 0 auto;
    padding: var(--spacing-3xl) var(--spacing-lg);
}

.article-header {
    margin-bottom: var(--spacing-2xl);
    padding-bottom: var(--spacing-xl);
    border-bottom: 1px solid var(--border-color);
}

.article-title {
    font-size: 36px;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: var(--spacing-md);
}

.article-meta {
    display: flex;
    gap: var(--spacing-lg);
    color: var(--text-muted);
    font-size: 14px;
}

.article-content {
    font-size: 17px;
    line-height: 1.8;
}

.article-content h2 {
    font-size: 26px;
    margin: var(--spacing-2xl) 0 var(--spacing-lg);
    color: var(--accent-primary);
}

.article-content h3 {
    font-size: 20px;
    margin: var(--spacing-xl) 0 var(--spacing-md);
}

.article-content p {
    margin-bottom: var(--spacing-lg);
    color: var(--text-secondary);
}

.article-content ul,
.article-content ol {
    margin: var(--spacing-lg) 0;
    padding-left: var(--spacing-xl);
    color: var(--text-secondary);
}

.article-content li {
    margin-bottom: var(--spacing-sm);
}

.article-content pre {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    overflow-x: auto;
    margin: var(--spacing-xl) 0;
}

.article-content code {
    font-family: var(--font-mono);
    font-size: 14px;
    color: var(--accent-primary);
}

.article-nav {
    margin-top: var(--spacing-3xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--border-color);
}

.article-content pre code {
    color: var(--text-primary);
}

/* ============================================
   Forms
   ============================================ */
.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
    color: var(--text-primary);
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: var(--spacing-md);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: inherit;
    font-size: 15px;
    transition: var(--transition-normal);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(0, 212, 255, 0.1);
}

.form-textarea {
    resize: vertical;
    min-height: 120px;
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    font-family: inherit;
    font-size: 15px;
    font-weight: 600;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition-normal);
}

.btn-primary {
    background: var(--accent-gradient);
    color: var(--bg-primary);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 30px rgba(0, 212, 255, 0.3);
}

.btn-outline {
    background: transparent;
    border: 1px solid var(--accent-primary);
    color: var(--accent-primary);
}

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

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

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-lg);
}

.footer-text {
    color: var(--text-muted);
    font-size: 14px;
}

.footer-links {
    display: flex;
    gap: var(--spacing-lg);
}

.footer-links a {
    color: var(--text-muted);
    font-size: 14px;
}

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

/* ============================================
   Utilities
   ============================================ */
.text-gradient {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.text-center { text-align: center; }
.text-muted { color: var(--text-muted); }

.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }
.mt-4 { margin-top: var(--spacing-xl); }

.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.mb-4 { margin-bottom: var(--spacing-xl); }

/* ============================================
   Animations
   ============================================ */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

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

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

@keyframes glow {
    0%, 100% { box-shadow: 0 0 20px rgba(0, 212, 255, 0.3); }
    50% { box-shadow: 0 0 40px rgba(0, 212, 255, 0.5); }
}

.animate-fade-in { animation: fadeIn 0.5s ease forwards; }
.animate-fade-in-up { animation: fadeInUp 0.5s ease forwards; }

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 768px) {
    .nav {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .nav-links {
        gap: var(--spacing-lg);
    }
    
    .hero {
        padding: 120px 0 60px;
    }
    
    .hero-title {
        font-size: 32px;
    }
    
    .cards-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
}