/* ===========================
   Variables & Reset
   =========================== */

:root {
    /* Colors - Teal Theme */
    --color-primary: #00796B;
    --color-secondary: #004D40;
    --color-accent: #00BFA5;
    --color-bg: #1A1A1A;
    --color-bg-alt: #252525;
    --color-text: #FFFFFF;
    --color-text-muted: #B0B0B0;
    --color-border: #333333;

    /* Typography */
    --font-primary: 'Source Sans Pro', -apple-system, BlinkMacSystemFont, 'Segoe UI', Arial, sans-serif;
    --font-code: 'JetBrains Mono', 'Source Code Pro', monospace;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

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

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

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

/* ===========================
   Typography
   =========================== */

h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
    margin-bottom: var(--spacing-sm);
}

h1 { font-size: 3rem; }
h2 { font-size: 2.5rem; }
h3 { font-size: 2rem; }
h4 { font-size: 1.5rem; }

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

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

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

/* ===========================
   Layout
   =========================== */

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.section {
    padding: var(--spacing-xl) 0;
    position: relative;
}

.section-title {
    text-align: center;
    margin-bottom: var(--spacing-md);
    font-size: 2.5rem;
    position: relative;
    display: inline-block;
    left: 50%;
    transform: translateX(-50%);
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: var(--color-accent);
    margin: var(--spacing-sm) auto 0;
    border-radius: 2px;
}

.section-subtitle {
    text-align: center;
    color: var(--color-text-muted);
    font-size: 1.2rem;
    margin-bottom: var(--spacing-lg);
}

/* ===========================
   Navigation
   =========================== */

#nav {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(26, 26, 26, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid var(--color-border);
}

#nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
}

#nav a {
    color: var(--color-text);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 4px;
    transition: all var(--transition-fast);
}

#nav a:hover {
    background: var(--color-primary);
    color: white;
}

/* ===========================
   Hero Section
   =========================== */

.hero-section {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    padding-top: 60px;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, var(--color-secondary) 0%, var(--color-bg) 50%, var(--color-secondary) 100%);
    opacity: 0.3;
    z-index: 0;
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 900px;
    padding: 0 var(--spacing-md);
}

.hero-title {
    font-size: clamp(3rem, 8vw, 4.5rem);
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, var(--color-accent), var(--color-primary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-tagline {
    font-size: clamp(1.5rem, 4vw, 2rem);
    color: var(--color-accent);
    margin-bottom: var(--spacing-xs);
}

.hero-subtitle {
    font-size: clamp(1rem, 2.5vw, 1.25rem);
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-lg);
}

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

/* Buttons */
.btn {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: 8px;
    font-weight: 600;
    transition: all var(--transition-normal);
    cursor: pointer;
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    background: var(--color-primary);
    box-shadow: 0 0 20px rgba(0, 191, 165, 0.5);
    transform: translateY(-2px);
}

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

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

.scroll-indicator {
    position: absolute;
    bottom: var(--spacing-md);
    left: 50%;
    transform: translateX(-50%);
    animation: bounce 2s infinite;
}

.scroll-indicator a {
    color: var(--color-accent);
    font-size: 2rem;
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateX(-50%) translateY(0);
    }
    40% {
        transform: translateX(-50%) translateY(-10px);
    }
    60% {
        transform: translateX(-50%) translateY(-5px);
    }
}

/* ===========================
   About Section
   =========================== */

.about-section {
    background: var(--color-bg-alt);
}

.timeline {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md);
}

/* Force 3+2 layout on medium screens (tablet) */
@media (min-width: 769px) and (max-width: 1199px) {
    .timeline {
        max-width: 900px;
        margin-left: auto;
        margin-right: auto;
    }

    /* Force line break after 3rd timeline box (6th child = 3 boxes + 3 arrows) */
    .timeline > *:nth-child(6) {
        margin-right: 100%;
    }
}

.timeline-item {
    text-align: center;
    padding: var(--spacing-sm);
    background: var(--color-bg);
    border-radius: 8px;
    border: 2px solid var(--color-border);
    transition: all var(--transition-normal);
    min-width: 140px;
}

.timeline-item.active {
    border-color: var(--color-accent);
    background: rgba(0, 191, 165, 0.1);
}

.timeline-item:hover {
    transform: translateY(-5px);
    border-color: var(--color-accent);
}

.timeline-year {
    font-size: 0.9rem;
    color: var(--color-text-muted);
}

.timeline-tech {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--color-accent);
    margin: var(--spacing-xs) 0;
}

.timeline-detail {
    font-size: 0.85rem;
    color: var(--color-text-muted);
}

.timeline-arrow {
    color: var(--color-accent);
    font-size: 1.5rem;
}

.about-content {
    max-width: 800px;
    margin: 0 auto var(--spacing-lg);
    text-align: center;
    font-size: 1.1rem;
    line-height: 1.8;
}

.stats-bar {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-md);
    max-width: 900px;
    margin: 0 auto;
}

.stat {
    text-align: center;
    padding: var(--spacing-sm);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--color-accent);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    color: var(--color-text-muted);
    text-transform: uppercase;
    font-size: 0.9rem;
    letter-spacing: 1px;
}

/* ===========================
   Responsive Design
   =========================== */

@media (max-width: 768px) {
    h1 { font-size: 2rem; }
    h2 { font-size: 1.75rem; }

    .section {
        padding: var(--spacing-lg) 0;
    }

    #nav ul {
        gap: var(--spacing-sm);
    }

    .timeline {
        flex-direction: column;
    }

    .timeline-arrow {
        transform: rotate(90deg);
    }

    .hero-cta {
        flex-direction: column;
    }

    .btn {
        width: 100%;
        text-align: center;
    }
}

@media (max-width: 480px) {
    :root {
        font-size: 14px;
    }

    .container {
        padding: 0 var(--spacing-sm);
    }

    #nav ul {
        flex-wrap: wrap;
        font-size: 0.9rem;
    }
}

/* ===========================
   Utility Classes
   =========================== */

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

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

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