/**
 * Hiro Imageboard — Global Design System
 * Version: 1.0.0
 *
 * Centralized styles for consistent spacing, typography, colors,
 * shadows, border-radius, animations, and responsive behavior.
 * WCAG 2.2 AA compliant.
 */

/* ============================================
   DESIGN TOKENS
   ============================================ */

:root {
    /* Colors */
    --color-primary: #007bff;
    --color-primary-dark: #0056b3;
    --color-primary-light: #e7f3ff;
    --color-bg: #f0f0f0;
    --color-surface: #fff;
    --color-text: #333;
    --color-text-muted: #666;
    --color-border: #ddd;
    --color-border-light: #e9ecef;
    --color-success: #28a745;
    --color-success-bg: #d4edda;
    --color-error: #dc3545;
    --color-error-bg: #f8d7da;
    --color-overlay: rgba(0, 0, 0, 0.9);
    --color-overlay-light: rgba(0, 123, 255, 0);

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
    --font-mono: "Courier New", monospace;
    --font-size-base: 16px;
    --line-height: 1.6;

    /* Spacing scale (4px base) */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 40px;
    --space-2xl: 60px;

    /* Border radius */
    --radius-sm: 5px;
    --radius-md: 8px;
    --radius-lg: 10px;
    --radius-pill: 20px;

    /* Shadows */
    --shadow-sm: 0 2px 5px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 5px 15px rgba(0, 0, 0, 0.3);
    --shadow-xl: 0 10px 40px rgba(0, 0, 0, 0.3);

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.4s ease;

    /* Layout */
    --max-width: 1200px;
    --header-height: 60px;

    /* Z-index scale */
    --z-header: 100;
    --z-modal: 1000;
    --z-notification: 10000;
    --z-overlay: 9999;
}

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

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

html {
    font-size: var(--font-size-base);
    -webkit-text-size-adjust: 100%;
    scroll-behavior: smooth;
}

body {
    background-color: var(--color-bg);
    font-family: var(--font-family);
    line-height: var(--line-height);
    color: var(--color-text);
    overflow-x: hidden;
    max-width: 100vw;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   PAGE TRANSITIONS
   ============================================ */

@keyframes fadeInPage {
    from {
        opacity: 0;
        transform: translateY(8px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

main {
    animation: fadeInPage var(--transition-base);
}

/* ============================================
   HEADER & NAVIGATION
   ============================================ */

header {
    background-color: var(--color-surface);
    box-shadow: var(--shadow-sm);
    padding: var(--space-md) var(--space-lg);
    position: sticky;
    top: 0;
    z-index: var(--z-header);
}

nav {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--space-md);
}

.logo {
    font-size: 24px;
    font-weight: bold;
    color: var(--color-text);
    text-decoration: none;
    transition: color var(--transition-base);
    white-space: nowrap;
}

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

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

.nav-links a {
    text-decoration: none;
    color: var(--color-text);
    font-size: var(--font-size-base);
    position: relative;
    padding: var(--space-xs) 0;
    transition: color var(--transition-base);
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-primary);
    transition: width var(--transition-base);
}

.nav-links a:hover,
.nav-links a:focus {
    color: var(--color-primary);
}

.nav-links a:hover::after,
.nav-links a:focus::after {
    width: 100%;
}

/* Search box */
.search-box {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.search-box input {
    padding: var(--space-sm) var(--space-md);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-pill);
    font-size: 14px;
    width: 200px;
    transition: border-color var(--transition-base), box-shadow var(--transition-base);
}

.search-box input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 4px rgba(0, 123, 255, 0.2);
}

/* ============================================
   BUTTONS
   ============================================ */

.login-btn,
.submit-btn,
.buy-btn,
.home-link,
.retry-btn {
    padding: var(--space-sm) var(--space-lg);
    background-color: var(--color-primary);
    color: #fff;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    text-decoration: none;
    display: inline-block;
    text-align: center;
    transition: background-color var(--transition-base), transform var(--transition-fast), box-shadow var(--transition-base);
    will-change: transform;
}

.login-btn:hover,
.submit-btn:hover,
.buy-btn:hover,
.home-link:hover,
.retry-btn:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.login-btn:active,
.submit-btn:active,
.buy-btn:active,
.home-link:active,
.retry-btn:active {
    transform: translateY(0);
}

/* ============================================
   IMAGE GRID
   ============================================ */

.imageboard {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: var(--space-sm);
    max-width: var(--max-width);
    margin: var(--space-lg) auto;
    padding: 0 var(--space-sm);
}

.image-container {
    aspect-ratio: 1 / 1;
    overflow: hidden;
    background-color: var(--color-border);
    cursor: pointer;
    position: relative;
    border-radius: var(--radius-sm);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
    will-change: transform;
}

.image-container::before {
    content: '';
    position: absolute;
    inset: 0;
    background: var(--color-overlay-light);
    transition: background var(--transition-base);
    z-index: 1;
    pointer-events: none;
}

.image-container:hover,
.image-container:focus {
    transform: scale(1.05);
    box-shadow: var(--shadow-lg);
}

.image-container:hover::before,
.image-container:focus::before {
    background: rgba(0, 123, 255, 0.1);
}

.image-container img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    transition: transform var(--transition-base);
    will-change: transform;
}

.image-container:hover img,
.image-container:focus img {
    transform: scale(1.1);
}

/* ============================================
   CARDS
   ============================================ */

.card {
    background-color: var(--color-surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    padding: var(--space-xl);
}

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

.content-section {
    max-width: 800px;
    margin: var(--space-2xl) auto;
    padding: var(--space-xl);
    background-color: var(--color-surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.content-section h1 {
    color: var(--color-text);
    margin-bottom: var(--space-lg);
    font-size: 32px;
}

.content-section p {
    color: var(--color-text-muted);
    font-size: var(--font-size-base);
    line-height: var(--line-height);
    margin-bottom: var(--space-md);
}

/* ============================================
   MODAL (Lightbox)
   ============================================ */

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--color-overlay);
    z-index: var(--z-modal);
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-base), visibility var(--transition-base);
}

.modal.is-open {
    opacity: 1;
    visibility: visible;
}

.modal img {
    max-width: 90vw;
    max-height: 90vh;
    object-fit: contain;
    border-radius: var(--radius-sm);
    transform: scale(0.95);
    transition: transform var(--transition-slow);
}

.modal.is-open img {
    transform: scale(1);
}

.modal-close {
    position: absolute;
    top: var(--space-lg);
    left: var(--space-lg);
    color: #fff;
    font-size: 40px;
    font-weight: bold;
    cursor: pointer;
    z-index: var(--z-modal) + 1;
    transition: color var(--transition-base);
    background: none;
    border: none;
    min-width: 44px;
    min-height: 44px;
    line-height: 1;
}

.modal-close:hover,
.modal-close:focus {
    color: var(--color-primary);
}

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

.site-footer {
    background-color: var(--color-surface);
    box-shadow: var(--shadow-sm);
    padding: var(--space-xl) var(--space-lg);
    margin-top: var(--space-2xl);
}

.site-footer .footer-content {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: var(--space-md);
}

.site-footer .footer-links {
    display: flex;
    gap: var(--space-lg);
    list-style: none;
    flex-wrap: wrap;
}

.site-footer .footer-links a {
    color: var(--color-text-muted);
    text-decoration: none;
    font-size: 14px;
    transition: color var(--transition-base);
}

.site-footer .footer-links a:hover,
.site-footer .footer-links a:focus {
    color: var(--color-primary);
}

.site-footer .footer-copy {
    color: var(--color-text-muted);
    font-size: 14px;
}

/* ============================================
   UPDATE NOTIFICATION
   ============================================ */

.update-notification {
    position: fixed;
    top: var(--space-lg);
    right: var(--space-lg);
    background-color: var(--color-primary);
    color: #fff;
    padding: var(--space-md) var(--space-lg);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-xl);
    z-index: var(--z-notification);
    display: flex;
    align-items: center;
    gap: var(--space-md);
    min-width: 300px;
    animation: slideInRight var(--transition-slow);
}

@keyframes slideInRight {
    from {
        transform: translateX(120%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.update-notification button {
    background-color: #fff;
    color: var(--color-primary);
    border: none;
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-weight: bold;
    min-height: 44px;
    min-width: 44px;
    transition: background-color var(--transition-fast);
}

.update-notification button:hover {
    background-color: var(--color-primary-light);
}

/* ============================================
   RESPONSIVE BREAKPOINTS
   ============================================ */

/* Tablet (≤1024px) */
@media (max-width: 1024px) {
    .nav-links {
        gap: var(--space-lg);
    }

    .search-box input {
        width: 160px;
    }
}

/* Mobile (≤768px) */
@media (max-width: 768px) {
    header {
        padding: var(--space-md);
    }

    nav {
        flex-wrap: wrap;
        gap: var(--space-sm);
    }

    .nav-links {
        gap: var(--space-md);
        font-size: 14px;
    }

    .search-box {
        flex: 1;
        min-width: 150px;
    }

    .search-box input {
        width: 100%;
        max-width: 200px;
    }

    .imageboard {
        grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
        gap: var(--space-xs);
        padding: 0 var(--space-xs);
    }

    .content-section {
        margin: var(--space-lg) auto;
        padding: var(--space-lg);
    }

    .content-section h1 {
        font-size: 28px;
    }

    .site-footer .footer-content {
        flex-direction: column;
        text-align: center;
    }
}

/* Small mobile (≤480px) */
@media (max-width: 480px) {
    .nav-links {
        gap: var(--space-sm);
    }

    .search-box input {
        max-width: 120px;
    }

    .imageboard {
        grid-template-columns: repeat(auto-fill, minmax(90px, 1fr));
    }

    .modal-close {
        top: var(--space-sm);
        left: var(--space-sm);
        font-size: 32px;
    }
}

/* ============================================
   GPU ACCELERATION
   ============================================ */

.image-container,
.modal,
.modal img,
.update-notification {
    will-change: transform, opacity;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

/* ============================================
   REDUCED MOTION
   ============================================ */

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }

    .image-container:hover,
    .image-container:focus,
    .splash-image:hover {
        transform: none;
    }

    .image-container:hover img,
    .image-container:focus img,
    .splash-image:hover img {
        transform: none;
    }

    main {
        animation: none;
    }
}