/* ============================================
   BlindBoard - Accessible Stylesheet
   WCAG 2.1 AA/AAA Compliant
   ============================================ */

/* === CSS Custom Properties === */
:root {
    /* Colors - High contrast dark theme */
    --bg: #0a0a0a;
    --surface: #141414;
    --surface-elevated: #1e1e1e;
    --text: #ffffff;
    --text-secondary: #e0e0e0;
    --muted: #a0a0a0;
    --accent: #6ea8fe;
    --accent-hover: #9ec5fe;
    --accent-subtle: rgba(110, 168, 254, 0.1);
    --border: #2a2a2a;
    --border-light: #3a3a3a;
    --focus-ring: #6ea8fe;
    --error: #ff6b6b;
    --success: #4ade80;
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    
    /* Typography */
    --font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
    --line-height: 1.7;
    --line-height-tight: 1.3;
    
    /* Border radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    
    /* Minimum touch target size (WCAG 2.5.5 AAA) */
    --touch-target-min: 44px;
    
    /* Z-index layers */
    --z-header: 100;
    --z-menu: 200;
    --z-overlay: 150;
    
    /* Max content width */
    --max-width: 900px;
    --max-width-narrow: 700px;
}

/* === 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;
    }
}

/* === Base Styles === */
*,
*::before,
*::after {
    box-sizing: border-box;
}

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    background: var(--bg);
    color: var(--text);
    margin: 0;
    padding: 0;
    line-height: var(--line-height);
    min-height: 100vh;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Prevent scroll when menu is open */
body.menu-open {
    overflow: hidden;
}

/* === Focus Styles (WCAG 2.4.7) === */
:focus {
    outline: 2px solid var(--focus-ring);
    outline-offset: 2px;
}

:focus:not(:focus-visible) {
    outline: none;
}

:focus-visible {
    outline: 3px solid var(--focus-ring);
    outline-offset: 2px;
}

/* === Skip Link (WCAG 2.4.1) === */
.skip-link {
    position: absolute;
    top: -100%;
    left: var(--space-md);
    z-index: calc(var(--z-menu) + 1);
    background: var(--accent);
    color: #000;
    padding: var(--space-sm) var(--space-md);
    font-weight: 600;
    text-decoration: none;
    border-radius: 0 0 4px 4px;
    transition: top var(--transition-fast);
}

.skip-link:focus {
    top: 0;
    outline-offset: 4px;
}

/* === Container === */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--space-xl) var(--space-lg);
}

/* === Typography === */
h1, h2, h3, h4, h5, h6 {
    margin-top: 0;
    line-height: var(--line-height-tight);
    font-weight: 600;
    letter-spacing: -0.02em;
}

h1 {
    font-size: clamp(2rem, 5vw, var(--font-size-4xl));
    margin-bottom: var(--space-lg);
    font-weight: 700;
}

h2 {
    font-size: clamp(1.5rem, 4vw, var(--font-size-2xl));
    margin-bottom: var(--space-lg);
    margin-top: var(--space-2xl);
    padding-bottom: var(--space-sm);
    border-bottom: 2px solid var(--border);
}

h3 {
    font-size: var(--font-size-xl);
    color: var(--accent);
    margin-bottom: var(--space-sm);
    margin-top: var(--space-lg);
}

p {
    margin-top: 0;
    margin-bottom: var(--space-md);
    color: var(--text-secondary);
}

/* Tagline styling */
.tagline {
    font-size: var(--font-size-xl);
    color: var(--muted);
    margin-bottom: var(--space-xl);
    max-width: var(--max-width-narrow);
}

/* === Links === */
a {
    color: var(--accent);
    text-decoration: underline;
    text-underline-offset: 3px;
    text-decoration-thickness: 1px;
    transition: color var(--transition-fast), text-decoration-thickness var(--transition-fast);
}

a:hover,
a:focus {
    color: var(--accent-hover);
    text-decoration-thickness: 2px;
}

/* === Header & Navigation === */
.site-header {
    position: sticky;
    top: 0;
    background: rgba(20, 20, 20, 0.98);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    z-index: var(--z-header);
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-md) var(--space-lg);
    max-width: var(--max-width);
    margin: 0 auto;
}

.logo {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--text);
    text-decoration: none;
}

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

/* === Hamburger Button (Accessible) === */
.hamburger {
    display: none;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 5px;
    width: var(--touch-target-min);
    height: var(--touch-target-min);
    padding: var(--space-sm);
    background: transparent;
    border: 2px solid transparent;
    border-radius: 4px;
    cursor: pointer;
    position: relative;
    z-index: var(--z-menu);
}

.hamburger:hover {
    background: var(--surface-elevated);
}

.hamburger:focus-visible {
    border-color: var(--focus-ring);
}

.hamburger-line {
    display: block;
    width: 24px;
    height: 3px;
    background: var(--text);
    border-radius: 2px;
    transition: transform var(--transition-base), opacity var(--transition-base);
    transform-origin: center;
}

/* Hamburger Animation */
.hamburger[aria-expanded="true"] .hamburger-line:nth-child(1) {
    transform: translateY(8px) rotate(45deg);
}

.hamburger[aria-expanded="true"] .hamburger-line:nth-child(2) {
    opacity: 0;
}

.hamburger[aria-expanded="true"] .hamburger-line:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
}

/* === Navigation Links === */
.nav-menu {
    display: flex;
    gap: var(--space-lg);
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-menu a {
    color: var(--text);
    text-decoration: none;
    font-size: var(--font-size-base);
    padding: var(--space-sm) var(--space-xs);
    border-radius: 4px;
    transition: color var(--transition-fast);
    display: inline-flex;
    align-items: center;
    min-height: var(--touch-target-min);
}

.nav-menu a:hover,
.nav-menu a:focus {
    color: var(--accent);
}

.nav-menu a[aria-current="page"] {
    color: var(--accent);
    font-weight: 600;
    position: relative;
}

.nav-menu a[aria-current="page"]::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: var(--space-xs);
    right: var(--space-xs);
    height: 2px;
    background: var(--accent);
}

/* === Menu Overlay === */
.menu-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.75);
    z-index: var(--z-overlay);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.menu-overlay.visible {
    display: block;
    opacity: 1;
}

/* === Mobile Navigation === */
@media (max-width: 750px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: 0;
        right: 0;
        width: min(280px, 80vw);
        height: 100vh;
        flex-direction: column;
        gap: 0;
        background: var(--surface);
        padding: calc(var(--touch-target-min) + var(--space-xl)) var(--space-lg) var(--space-lg);
        border-left: 1px solid var(--border);
        transform: translateX(100%);
        transition: transform var(--transition-base);
        z-index: var(--z-menu);
        overflow-y: auto;
    }
    
    .nav-menu.is-open {
        transform: translateX(0);
    }
    
    .nav-menu li {
        border-bottom: 1px solid var(--border);
    }
    
    .nav-menu li:last-child {
        border-bottom: none;
    }
    
    .nav-menu a {
        display: flex;
        width: 100%;
        padding: var(--space-md);
        font-size: var(--font-size-lg);
        min-height: var(--touch-target-min);
    }
    
    .nav-menu a[aria-current="page"]::after {
        display: none;
    }
    
    .nav-menu a[aria-current="page"] {
        background: var(--surface-elevated);
    }
}

/* === Buttons === */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    min-height: var(--touch-target-min);
    padding: var(--space-md) var(--space-xl);
    background: var(--accent);
    color: #000;
    font-size: var(--font-size-base);
    font-weight: 600;
    text-decoration: none;
    border: 2px solid transparent;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: background var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

.btn:hover,
.btn:focus {
    background: var(--accent-hover);
    color: #000;
    text-decoration: none;
    box-shadow: var(--shadow-md);
}

.btn:focus-visible {
    border-color: var(--text);
    outline: 3px solid var(--focus-ring);
    outline-offset: 2px;
}

.btn:active {
    transform: scale(0.98);
}

/* Disabled button */
.btn.disabled-btn,
.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: none;
}

/* === Sections === */
main {
    min-height: 50vh;
    padding-bottom: var(--space-2xl);
}

section {
    margin: var(--space-2xl) 0;
}

section:first-of-type {
    margin-top: var(--space-lg);
}

/* === Lists === */
ol, ul {
    padding-left: var(--space-xl);
    margin-bottom: var(--space-lg);
}

li {
    margin-bottom: var(--space-sm);
    color: var(--text-secondary);
}

li::marker {
    color: var(--accent);
}

/* Strong text */
strong {
    color: var(--text);
    font-weight: 600;
}

/* === Footer === */
.site-footer {
    margin-top: auto;
    padding: var(--space-2xl) var(--space-lg);
    border-top: 1px solid var(--border);
    background: var(--surface);
    text-align: center;
    color: var(--muted);
}

.footer-links {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--space-lg);
    margin-bottom: var(--space-lg);
}

.footer-links a {
    color: var(--muted);
    text-decoration: none;
    padding: var(--space-xs) var(--space-sm);
    min-height: var(--touch-target-min);
    display: inline-flex;
    align-items: center;
    border-radius: var(--radius-sm);
    transition: color var(--transition-fast), background var(--transition-fast);
}

.footer-links a:hover,
.footer-links a:focus {
    color: var(--accent);
    background: var(--accent-subtle);
}

.footer-copyright {
    font-size: var(--font-size-sm);
    margin: 0;
}

/* === Screen Reader Only (Visually Hidden) === */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* === Live Region Announcements === */
.sr-announcer {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* === Responsive Adjustments === */
@media (max-width: 480px) {
    .container {
        padding: var(--space-md);
    }
    
    .navbar {
        padding: var(--space-md);
    }
    
    .footer-links {
        flex-direction: column;
        gap: var(--space-sm);
    }
}

/* === Print Styles === */
@media print {
    .site-header,
    .hamburger,
    .menu-overlay {
        display: none !important;
    }
    
    body {
        background: white;
        color: black;
    }
    
    a {
        color: black;
        text-decoration: underline;
    }
}