:root {
    --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-theme: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    --font-primary: 'IBM Plex Sans', -apple-system, sans-serif;
    --font-mono: 'IBM Plex Mono', monospace;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 8rem;
}

/* Dark Theme (default) */
[data-theme="dark"] {
    --color-bg: #0a0a0a;
    --color-bg-elevated: #111111;
    --color-bg-subtle: #161616;
    --color-text: #e8e8e8;
    --color-text-muted: #888888;
    --color-text-subtle: #555555;
    --color-accent: #c9a962;
    --color-accent-subtle: rgba(201, 169, 98, 0.15);
    --color-border: #222222;
    --color-border-subtle: #1a1a1a;
}

/* Light Theme */
[data-theme="light"] {
    --color-bg: #f8f7f4;
    --color-bg-elevated: #ffffff;
    --color-bg-subtle: #f0efe9;
    --color-text: #1a1a1a;
    --color-text-muted: #666666;
    --color-text-subtle: #999999;
    --color-accent: #9a7b4f;
    --color-accent-subtle: rgba(154, 123, 79, 0.1);
    --color-border: #e0ddd5;
    --color-border-subtle: #eae7df;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
    font-family: var(--font-primary);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    font-weight: 300;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    transition: background-color var(--transition-theme), color var(--transition-theme);
}

/* Navigation */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: var(--color-bg);
    opacity: 0.95;
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-border-subtle);
    transition: background-color var(--transition-theme), border-color var(--transition-theme);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-sm) var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    font-weight: 500;
    letter-spacing: 0.2em;
    color: var(--color-text);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.nav-logo:hover { color: var(--color-accent); }

.nav-right {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

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

.nav-links a {
    font-size: 0.75rem;
    font-weight: 400;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--color-text-muted);
    text-decoration: none;
    transition: color var(--transition-fast);
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 1px;
    background: var(--color-accent);
    transition: width var(--transition-fast);
}

.nav-links a:hover { color: var(--color-text); }
.nav-links a:hover::after { width: 100%; }
.nav-links a.active { color: var(--color-text); }

/* Theme Toggle */
.theme-toggle {
    display: flex;
    align-items: center;
    gap: 8px;
    background: none;
    border: 1px solid var(--color-border-subtle);
    padding: 6px 10px;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.theme-toggle:hover { border-color: var(--color-border); }

.theme-toggle-icon {
    width: 14px;
    height: 14px;
    color: var(--color-text-muted);
    transition: color var(--transition-fast);
}

.theme-toggle:hover .theme-toggle-icon { color: var(--color-accent); }

.theme-toggle-label {
    font-family: var(--font-mono);
    font-size: 0.5625rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--color-text-subtle);
    transition: color var(--transition-fast);
}

[data-theme="dark"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: none; }

/* Mobile Nav Toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 5px;
}

.nav-toggle span {
    width: 20px;
    height: 1px;
    background: var(--color-text);
    transition: var(--transition-fast);
}

/* Page Header */
.page-header {
    padding: calc(var(--spacing-xl) + 60px) var(--spacing-md) var(--spacing-lg);
    border-bottom: 1px solid var(--color-border-subtle);
    transition: border-color var(--transition-theme);
}

.page-header-content {
    max-width: 1200px;
    margin: 0 auto;
}

.page-eyebrow {
    font-family: var(--font-mono);
    font-size: 0.625rem;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    color: var(--color-accent);
    margin-bottom: var(--spacing-sm);
    opacity: 0;
    animation: fadeUp 0.6s ease-out 0.2s forwards;
}

.page-title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 300;
    letter-spacing: -0.02em;
    margin-bottom: var(--spacing-md);
    opacity: 0;
    animation: fadeUp 0.6s ease-out 0.3s forwards;
}

.page-intro {
    font-size: 1.125rem;
    color: var(--color-text-muted);
    max-width: 700px;
    opacity: 0;
    animation: fadeUp 0.6s ease-out 0.4s forwards;
}

/* Section Styles */
.section {
    padding: var(--spacing-xl) var(--spacing-md);
    position: relative;
    transition: background-color var(--transition-theme);
}

.section-container {
    max-width: 1200px;
    margin: 0 auto;
}

.section-header {
    margin-bottom: var(--spacing-lg);
}

.section-eyebrow {
    font-family: var(--font-mono);
    font-size: 0.625rem;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    color: var(--color-text-subtle);
    margin-bottom: var(--spacing-sm);
}

.section-title {
    font-size: clamp(1.75rem, 3vw, 2.25rem);
    font-weight: 300;
    letter-spacing: -0.01em;
}

/* Footer */
.footer {
    padding: var(--spacing-lg) var(--spacing-md);
    border-top: 1px solid var(--color-border-subtle);
    transition: border-color var(--transition-theme);
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-logo {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 0.2em;
    color: var(--color-text-subtle);
}

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

.footer-links a {
    font-size: 0.6875rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--color-text-subtle);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

.footer-copy {
    font-size: 0.6875rem;
    color: var(--color-text-subtle);
}

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

.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Responsive */
@media (max-width: 768px) {
    .nav-right { gap: var(--spacing-sm); }

    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--color-bg);
        border-bottom: 1px solid var(--color-border-subtle);
        flex-direction: column;
        padding: var(--spacing-md);
        gap: var(--spacing-sm);
    }

    .nav-links.active { display: flex; }
    .nav-toggle { display: flex; }
    .theme-toggle-label { display: none; }

    .footer-container {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }

    .footer-links {
        flex-wrap: wrap;
        justify-content: center;
    }
}