/* ========================================
   SHARED CSS VARIABLES & RESET
   Tristan Huynh Photography Portfolio
======================================== */

:root {
    /* Color System */
    --bg-primary: #0a0a0a;
    --bg-secondary: #121212;
    --bg-tertiary: #1a1a1a;
    --bg-card: rgba(255, 255, 255, 0.03);
    --bg-glass: rgba(255, 255, 255, 0.05);
    --bg-overlay: rgba(10, 10, 10, 0.95);

    --text-primary: #f5f3ef;
    --text-secondary: #a8a4a0;
    --text-muted: #6b6865;

    --accent-gold: #c9a96e;
    --accent-gold-light: #d4bc8a;
    --accent-gold-dark: #a88b4a;
    --accent-red: #c96e6e;

    /* Typography */
    --font-display: 'Playfair Display', Georgia, serif;
    --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;

    /* Spacing */
    --section-padding: clamp(5rem, 12vw, 10rem);
    --container-width: min(90%, 1400px);
    --container-narrow: min(85%, 900px);

    /* Transitions */
    --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-smooth: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ========================================
   UNIFIED HEADER
======================================== */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 1rem 0;
    transition: var(--transition-smooth);
}

.site-header.transparent {
    background: transparent;
    padding: 1.5rem 0;
}

.site-header.solid,
.site-header.scrolled {
    background: rgba(10, 10, 10, 0.95);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    padding: 1rem 0;
}

.header-container {
    width: var(--container-width);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* Logo */
.header-logo {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.header-logo img {
    height: 55px;
    width: auto;
    filter: brightness(0) invert(1);
    opacity: 0.9;
    transition: var(--transition-fast);
}

.header-logo:hover img {
    opacity: 1;
}

/* Navigation Links */
.header-nav {
    display: flex;
    gap: 2.5rem;
    list-style: none;
    margin: 0;
    padding: 0;
}

.header-nav a {
    font-size: 0.875rem;
    font-weight: 400;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--text-secondary);
    text-decoration: none;
    transition: var(--transition-fast);
    position: relative;
}

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

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

.header-nav a:hover::after {
    width: 100%;
}

.header-nav a.active {
    color: var(--accent-gold);
}

.header-nav a.active::after {
    width: 100%;
}

/* Back Link */
.header-back {
    font-size: 0.8125rem;
    font-weight: 400;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--text-secondary);
    text-decoration: none;
    transition: var(--transition-fast);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.header-back:hover {
    color: var(--accent-gold);
}

/* Right section container */
.header-right {
    display: flex;
    align-items: center;
    gap: 2rem;
}

/* Mobile Toggle */
.header-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 0.5rem;
    background: none;
    border: none;
}

.header-toggle span {
    width: 24px;
    height: 1.5px;
    background: var(--text-primary);
    transition: var(--transition-fast);
}

/* ========================================
   UNIFIED FOOTER
======================================== */
.site-footer {
    padding: 2rem 0;
    text-align: center;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    background: var(--bg-secondary);
}

.site-footer p {
    font-size: 0.8125rem;
    color: var(--text-muted);
}

.footer-signature {
    width: 120px;
    margin: 0 auto 1.5rem;
    opacity: 0.5;
    filter: brightness(0) invert(1);
}

/* ========================================
   RESPONSIVE
======================================== */
@media (max-width: 768px) {
    .header-nav {
        display: none;
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        background: rgba(10, 10, 10, 0.98);
        flex-direction: column;
        padding: 2rem;
        gap: 1.5rem;
        border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    }

    .header-nav.open {
        display: flex;
    }

    .header-toggle {
        display: flex;
    }

    .header-logo img {
        height: 45px;
    }
}