/* ==========================================================================
   22B1 Design System - Layout
   Header, footer, navigation, grid systems, and page structure
   ========================================================================== */

/* ==========================================================================
   CONTAINER
   ========================================================================== */

.container {
    width: 100%;
    max-width: var(--container-xl);
    margin: 0 auto;
    padding: 0 var(--space-6);
}

.container-narrow {
    max-width: var(--container-md);
}

.container-wide {
    max-width: var(--container-2xl);
}

.container-content {
    max-width: var(--content-width);
}

/* ==========================================================================
   SITE HEADER
   ========================================================================== */

.site-header {
    position: sticky;
    top: 0;
    z-index: var(--z-sticky);
    background: var(--color-bg-overlay);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
    gap: var(--space-6);
}

/* Logo */
.site-logo {
    display: flex;
    flex-direction: column;
    text-decoration: none;
    transition: opacity var(--duration-fast);
}

.site-logo:hover {
    opacity: 0.8;
}

.logo-text {
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    letter-spacing: var(--tracking-tight);
    line-height: 1.2;
}

.logo-subtitle {
    font-family: var(--font-ui);
    font-size: var(--text-xs);
    font-weight: var(--font-weight-medium);
    text-transform: uppercase;
    letter-spacing: var(--tracking-widest);
    color: var(--color-brand-gold);
}

/* Back link in header */
.header-back {
    font-family: var(--font-ui);
    font-size: var(--text-sm);
    color: var(--color-text-tertiary);
    transition: color var(--duration-fast);
    margin-left: var(--space-4);
}

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

/* Main Navigation */
.main-nav ul {
    display: flex;
    align-items: center;
    gap: var(--space-6);
}

.main-nav a {
    font-family: var(--font-ui);
    font-size: var(--text-sm);
    font-weight: var(--font-weight-medium);
    color: var(--color-text-tertiary);
    padding: var(--space-2) 0;
    position: relative;
    transition: color var(--duration-fast);
}

.main-nav a:hover,
.main-nav a[aria-current="page"] {
    color: var(--color-text-primary);
}

.main-nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--color-brand-gold);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--duration-base) var(--ease-smooth);
}

.main-nav a:hover::after,
.main-nav a[aria-current="page"]::after {
    transform: scaleX(1);
}

/* Mobile Menu Toggle */
.mobile-menu-checkbox {
    display: none;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 44px;
    height: 44px;
    cursor: pointer;
    z-index: calc(var(--z-sticky) + 1);
}

.mobile-menu-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--color-text-secondary);
    margin: 3px 0;
    border-radius: 1px;
    transition: all var(--duration-base) var(--ease-out);
}

.mobile-menu-toggle:hover span {
    background: var(--color-brand-gold);
}

/* ==========================================================================
   PAGE HEADER
   ========================================================================== */

.page-header {
    background: var(--color-bg-elevated);
    padding: var(--space-16) 0;
    border-bottom: 1px solid var(--color-border);
}

.page-header h1 {
    margin-bottom: var(--space-4);
}

.page-header .lead {
    max-width: 60ch;
}

/* Breadcrumb */
.breadcrumb {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--space-2);
    font-family: var(--font-ui);
    font-size: var(--text-sm);
    color: var(--color-text-tertiary);
    margin-bottom: var(--space-4);
}

.breadcrumb a {
    color: var(--color-text-tertiary);
    transition: color var(--duration-fast);
}

.breadcrumb a:hover {
    color: var(--color-brand-gold);
}

.breadcrumb span {
    color: var(--color-text-muted);
}

/* ==========================================================================
   HERO SECTION
   ========================================================================== */

.hero {
    position: relative;
    padding: var(--space-24) 0;
    background: var(--color-bg-elevated);
    border-bottom: 1px solid var(--color-border);
    overflow: hidden;
}

/* Atmospheric background gradient */
.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background: 
        radial-gradient(ellipse at 30% 20%, var(--color-brand-gold-subtle) 0%, transparent 50%),
        radial-gradient(ellipse at 70% 80%, var(--color-accent-blue-subtle) 0%, transparent 50%);
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: var(--container-md);
}

.hero h1 {
    margin-bottom: var(--space-6);
    line-height: 1.1;
}

.hero-lead {
    font-size: var(--text-lg);
    color: var(--color-text-secondary);
    margin-bottom: var(--space-8);
    max-width: 55ch;
}

.hero-cta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-4);
}

/* ==========================================================================
   MAIN CONTENT SECTIONS
   ========================================================================== */

.section {
    padding: var(--space-20) 0;
}

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

.section-header {
    margin-bottom: var(--space-12);
}

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

.section-header h2 {
    margin-bottom: var(--space-4);
}

.section-lead {
    font-size: var(--text-lg);
    color: var(--color-text-secondary);
    max-width: 60ch;
}

.section-header.text-center .section-lead {
    margin: 0 auto;
}

/* Article content wrapper */
.article-content {
    max-width: var(--container-md);
    margin: 0 auto;
}

.article-content h2 {
    margin-top: var(--space-12);
    padding-top: var(--space-8);
    border-top: 1px solid var(--color-border);
}

.article-content h2:first-child {
    margin-top: 0;
    padding-top: 0;
    border-top: none;
}

.article-content h3 {
    margin-top: var(--space-8);
}

/* ==========================================================================
   GRID SYSTEMS
   ========================================================================== */

/* Auto-fit grids */
.grid {
    display: grid;
    gap: var(--space-6);
}

.grid-2 {
    grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
    grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
    grid-template-columns: repeat(4, 1fr);
}

.grid-auto-fit {
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.grid-auto-fit-sm {
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

.grid-auto-fit-lg {
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
}

/* Two column layout */
.two-column {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-12);
    align-items: start;
}

/* ==========================================================================
   SITE FOOTER
   ========================================================================== */

.site-footer {
    background: var(--color-bg);
    border-top: 1px solid var(--color-border);
    padding: var(--space-16) 0 var(--space-8);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr repeat(3, 1fr);
    gap: var(--space-12);
    margin-bottom: var(--space-12);
}

.footer-brand {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.footer-brand .logo-text {
    font-size: var(--text-base);
}

.footer-brand p {
    font-size: var(--text-sm);
    color: var(--color-text-tertiary);
    max-width: 30ch;
}

.footer-section h4 {
    font-family: var(--font-ui);
    font-size: var(--text-xs);
    font-weight: var(--font-weight-semibold);
    text-transform: uppercase;
    letter-spacing: var(--tracking-widest);
    color: var(--color-brand-gold);
    margin-bottom: var(--space-4);
}

.footer-section ul {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.footer-section a {
    font-family: var(--font-ui);
    font-size: var(--text-sm);
    color: var(--color-text-tertiary);
    transition: color var(--duration-fast);
}

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

.footer-bottom {
    padding-top: var(--space-8);
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.footer-bottom p {
    font-family: var(--font-ui);
    font-size: var(--text-sm);
    color: var(--color-text-tertiary);
    margin-bottom: var(--space-2);
    max-width: none;
}

.footer-note {
    font-size: var(--text-xs);
    color: var(--color-text-muted);
    max-width: 60ch;
    margin: 0 auto;
}

/* Minimal footer variant */
.footer-minimal {
    padding: var(--space-8) 0;
}

.footer-minimal .footer-bottom {
    padding-top: 0;
    border-top: none;
}

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

@media (max-width: 1024px) {
    .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: var(--space-8);
    }
}

@media (max-width: 768px) {
    .container {
        padding: 0 var(--space-4);
    }
    
    /* Mobile navigation */
    .mobile-menu-toggle {
        display: flex;
    }
    
    .main-nav {
        position: fixed;
        top: 64px;
        left: 0;
        right: 0;
        bottom: 0;
        background: var(--color-bg);
        padding: var(--space-8);
        transform: translateX(100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--duration-base) var(--ease-out);
        overflow-y: auto;
    }
    
    .mobile-menu-checkbox:checked ~ .main-nav {
        transform: translateX(0);
        opacity: 1;
        visibility: visible;
    }
    
    .main-nav ul {
        flex-direction: column;
        gap: 0;
    }
    
    .main-nav li {
        border-bottom: 1px solid var(--color-border);
    }
    
    .main-nav a {
        display: block;
        padding: var(--space-4) 0;
        font-size: var(--text-base);
    }
    
    .main-nav a::after {
        display: none;
    }
    
    /* Hamburger animation */
    .mobile-menu-checkbox:checked + .mobile-menu-toggle span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .mobile-menu-checkbox:checked + .mobile-menu-toggle span:nth-child(2) {
        opacity: 0;
    }
    
    .mobile-menu-checkbox:checked + .mobile-menu-toggle span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }
    
    /* Section spacing */
    .section {
        padding: var(--space-12) 0;
    }
    
    .page-header {
        padding: var(--space-10) 0;
    }
    
    .hero {
        padding: var(--space-16) 0;
    }
    
    /* Grid adjustments */
    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }
    
    .two-column {
        grid-template-columns: 1fr;
        gap: var(--space-8);
    }
    
    /* Footer */
    .footer-grid {
        grid-template-columns: 1fr;
        gap: var(--space-8);
    }
    
    .footer-brand {
        margin-bottom: var(--space-4);
    }
    
    /* Hero */
    .hero-cta {
        flex-direction: column;
    }
    
    .hero-cta .btn {
        width: 100%;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--space-3);
    }
    
    h1 {
        font-size: var(--text-3xl);
    }
    
    h2 {
        font-size: var(--text-xl);
    }
    
    .hero h1 {
        font-size: var(--text-3xl);
    }
}