/* ===================================
   BASE STYLES & CSS VARIABLES
   =================================== */

:root {
    /* Color Palette - Default (Dark Theme) */
    --bg-primary: #0f0f23;
    --bg-secondary: #1a1a2e;
    --bg-tertiary: #16213e;
    --text-primary: #e4e4e7;
    --text-secondary: #a1a1aa;
    --accent-color: #3b82f6;
    --accent-hover: #2563eb;
    --border-color: #27272a;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    
    /* Typography */
    --font-primary: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-mono: 'Consolas', 'Monaco', 'Courier New', monospace;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 var(--shadow-color);
    --shadow-md: 0 4px 6px -1px var(--shadow-color);
    --shadow-lg: 0 10px 15px -3px var(--shadow-color);
    --shadow-xl: 0 20px 25px -5px var(--shadow-color);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 300ms ease-in-out;
    --transition-slow: 500ms ease-in-out;
    
    /* Layout */
    --max-width: 1200px;
    --nav-height: 70px;
}

/* ===================================
   RESET & BASE STYLES
   =================================== */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

body {
    font-family: var(--font-primary);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

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

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

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

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

ul {
    list-style: none;
}

h1, h2, h3, h4, h5, h6 {
    line-height: 1.2;
    font-weight: 600;
    color: var(--text-primary);
}

h1 {
    font-size: 2.5rem;
}

h2 {
    font-size: 2rem;
}

h3 {
    font-size: 1.5rem;
}

h4 {
    font-size: 1.25rem;
}

p {
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
}

/* ===================================
   BUTTON STYLES
   =================================== */

.btn {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-weight: 600;
    text-align: center;
    transition: all var(--transition-fast);
    cursor: pointer;
    text-decoration: none;
    border: 2px solid transparent;
    font-size: 1rem;
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.1rem;
}

.btn-small {
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-color), #2563eb);
    color: white;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.4);
    background: linear-gradient(135deg, #2563eb, var(--accent-color));
}

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

.btn-secondary:hover {
    background-color: var(--bg-secondary);
    border-color: var(--accent-color);
    transform: translateY(-2px);
}

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

.btn-outline:hover {
    background-color: var(--accent-color);
    color: white;
    transform: translateY(-2px);
}

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

/* ===================================
   UTILITY CLASSES
   =================================== */

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.section-title {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: var(--spacing-xl);
    color: var(--text-primary);
}

.highlight {
    color: var(--accent-color);
    font-weight: 700;
}

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

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.fade-in {
    animation: fadeIn 0.6s ease-out forwards;
    opacity: 0;
}

.fade-in:nth-child(1) { animation-delay: 0.1s; }
.fade-in:nth-child(2) { animation-delay: 0.2s; }
.fade-in:nth-child(3) { animation-delay: 0.3s; }
.fade-in:nth-child(4) { animation-delay: 0.4s; }
.fade-in:nth-child(5) { animation-delay: 0.5s; }
.fade-in:nth-child(6) { animation-delay: 0.6s; }

/* ===================================
   RESPONSIVE DESIGN
   =================================== */

@media (max-width: 768px) {
    html {
        font-size: 14px;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    h2 {
        font-size: 1.75rem;
    }
    
    h3 {
        font-size: 1.25rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    h1 {
        font-size: 1.75rem;
    }
    
    h2 {
        font-size: 1.5rem;
    }
}