/* ========================================
   UNTITLED PUBLISHERS - MAIN STYLESHEET
   Cyberpunk Publishing Aesthetic
   ======================================== */

/* ========================================
   CSS Variables
   ======================================== */
:root {
    /* Colors */
    --color-bg: #09090b;
    --color-bg-elevated: #18181b;
    --color-bg-card: #1c1c1f;
    --color-surface: #27272a;
    --color-border: #3f3f46;
    --color-border-light: #52525b;
    
    --color-text: #fafafa;
    --color-text-muted: #a1a1aa;
    --color-text-dim: #71717a;
    
    --color-primary: #f97316;
    --color-primary-light: #fb923c;
    --color-primary-dark: #ea580c;
    --color-primary-glow: rgba(249, 115, 22, 0.4);
    
    --color-accent: #22d3ee;
    --color-success: #22c55e;
    --color-warning: #eab308;
    --color-error: #ef4444;
    
    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    
    /* 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;
    --space-4xl: 6rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.6);
    --shadow-glow: 0 0 40px var(--color-primary-glow);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms ease;
    
    /* Layout */
    --container-max: 1200px;
    --header-height: 80px;
}

/* ========================================
   Reset & Base
   ======================================== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: inherit;
    text-decoration: none;
    transition: color var(--transition-fast);
}

ul, ol {
    list-style: none;
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

input, textarea, select {
    font-family: inherit;
    font-size: inherit;
}

/* ========================================
   Utility Classes
   ======================================== */
.container {
    width: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

.text-gradient {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-tag {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-primary);
    padding: var(--space-xs) var(--space-md);
    background: rgba(249, 115, 22, 0.1);
    border: 1px solid rgba(249, 115, 22, 0.3);
    border-radius: var(--radius-full);
    margin-bottom: var(--space-md);
}

.section-header {
    text-align: center;
    max-width: 600px;
    margin: 0 auto var(--space-3xl);
}

.section-title {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: var(--space-md);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--color-text-muted);
}

/* ========================================
   Buttons
   ======================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-sm) var(--space-lg);
    font-weight: 600;
    font-size: 0.9375rem;
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    white-space: nowrap;
}

.btn-primary {
    background: var(--color-primary);
    color: white;
}

.btn-primary:hover {
    background: var(--color-primary-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
}

.btn-secondary {
    background: transparent;
    color: var(--color-text);
    border: 1px solid var(--color-border-light);
}

.btn-secondary:hover {
    background: var(--color-surface);
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.btn-lg {
    padding: var(--space-md) var(--space-xl);
    font-size: 1rem;
}

/* ========================================
   Header & Navigation
   ======================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(9, 9, 11, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-border);
    height: var(--header-height);
}

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

.logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-weight: 800;
    font-size: 1.25rem;
    letter-spacing: -0.02em;
}

.logo-icon {
    font-size: 1.5rem;
}

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

.nav-links {
    display: flex;
    align-items: center;
    gap: var(--space-xl);
}

.nav-links a {
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text-muted);
    transition: color var(--transition-fast);
}

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

.mobile-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 28px;
    height: 28px;
    padding: 0;
}

.mobile-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--color-text);
    border-radius: 1px;
    transition: all var(--transition-fast);
}

.mobile-toggle.active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.mobile-toggle.active span:nth-child(2) {
    opacity: 0;
}

.mobile-toggle.active span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: var(--header-height);
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(ellipse at 50% 0%, rgba(249, 115, 22, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse at 100% 50%, rgba(34, 211, 238, 0.1) 0%, transparent 40%),
        linear-gradient(180deg, var(--color-bg) 0%, var(--color-bg-elevated) 100%);
    pointer-events: none;
}

.hero-bg::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        linear-gradient(rgba(249, 115, 22, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(249, 115, 22, 0.03) 1px, transparent 1px);
    background-size: 50px 50px;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 800px;
    padding: var(--space-4xl) 0;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    font-family: var(--font-mono);
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--color-primary);
    padding: var(--space-sm) var(--space-md);
    background: rgba(249, 115, 22, 0.1);
    border: 1px solid rgba(249, 115, 22, 0.3);
    border-radius: var(--radius-full);
    margin-bottom: var(--space-xl);
    animation: pulse 2s ease-in-out infinite;
}

.badge-dot {
    width: 8px;
    height: 8px;
    background: var(--color-primary);
    border-radius: 50%;
    animation: blink 1.5s ease-in-out infinite;
}

@keyframes blink {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.4; }
}

@keyframes pulse {
    0%, 100% { box-shadow: 0 0 0 0 rgba(249, 115, 22, 0.2); }
    50% { box-shadow: 0 0 0 8px rgba(249, 115, 22, 0); }
}

.hero-title {
    font-size: clamp(3rem, 8vw, 5rem);
    font-weight: 900;
    line-height: 1.05;
    letter-spacing: -0.03em;
    margin-bottom: var(--space-lg);
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--color-text-muted);
    max-width: 540px;
    margin-bottom: var(--space-2xl);
}

.hero-buttons {
    display: flex;
    gap: var(--space-md);
    flex-wrap: wrap;
}

.hero-scroll {
    position: absolute;
    bottom: var(--space-2xl);
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-sm);
    color: var(--color-text-dim);
    font-size: 0.75rem;
    font-family: var(--font-mono);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.scroll-line {
    width: 1px;
    height: 60px;
    background: linear-gradient(180deg, var(--color-primary) 0%, transparent 100%);
    animation: scrollPulse 2s ease-in-out infinite;
}

@keyframes scrollPulse {
    0%, 100% { opacity: 1; transform: scaleY(1); }
    50% { opacity: 0.5; transform: scaleY(0.8); }
}

/* ========================================
   Programs Section
   ======================================== */
.programs {
    padding: var(--space-4xl) 0;
    background: var(--color-bg-elevated);
}

.programs-tabs {
    display: flex;
    justify-content: center;
    gap: var(--space-sm);
    margin-bottom: var(--space-3xl);
    flex-wrap: wrap;
}

.tab-btn {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-xl);
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text-muted);
    font-weight: 500;
    transition: all var(--transition-base);
}

.tab-btn:hover {
    border-color: var(--color-border-light);
    color: var(--color-text);
}

.tab-btn.active {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: white;
}

.tab-number {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    opacity: 0.6;
}

.tab-panel {
    display: none;
}

.tab-panel.active {
    display: block;
    animation: fadeIn 0.4s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.program-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-3xl);
    align-items: center;
}

.program-info h3 {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: var(--space-md);
}

.program-info > p {
    color: var(--color-text-muted);
    margin-bottom: var(--space-xl);
}

.program-features {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
    margin-bottom: var(--space-xl);
}

.program-features li {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    color: var(--color-text-muted);
}

.program-features svg {
    color: var(--color-success);
    flex-shrink: 0;
}

.visual-card {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    padding: var(--space-3xl);
    text-align: center;
}

.visual-icon {
    font-size: 4rem;
    margin-bottom: var(--space-xl);
}

.visual-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-xl);
}

.stat {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
}

.stat-value {
    font-size: 2rem;
    font-weight: 800;
    color: var(--color-primary);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--color-text-muted);
}

/* ========================================
   Why Different Section
   ======================================== */
.why-different {
    padding: var(--space-4xl) 0;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-lg);
}

.feature-card {
    background: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    transition: all var(--transition-base);
}

.feature-card:hover {
    border-color: var(--color-primary);
    transform: translateY(-4px);
}

.feature-icon {
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(249, 115, 22, 0.1);
    border-radius: var(--radius-md);
    color: var(--color-primary);
    margin-bottom: var(--space-lg);
}

.feature-card h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--space-sm);
}

.feature-card p {
    font-size: 0.9375rem;
    color: var(--color-text-muted);
}

/* ========================================
   CTA Section
   ======================================== */
.cta-section {
    padding: var(--space-4xl) 0;
    background: linear-gradient(135deg, var(--color-bg-elevated) 0%, var(--color-bg) 100%);
    position: relative;
    overflow: hidden;
}

.cta-section::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 800px;
    height: 800px;
    background: radial-gradient(circle, rgba(249, 115, 22, 0.1) 0%, transparent 60%);
    pointer-events: none;
}

.cta-content {
    position: relative;
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.cta-content h2 {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 800;
    margin-bottom: var(--space-md);
}

.cta-content p {
    font-size: 1.125rem;
    color: var(--color-text-muted);
    margin-bottom: var(--space-2xl);
}

.cta-buttons {
    display: flex;
    gap: var(--space-md);
    justify-content: center;
    flex-wrap: wrap;
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background: var(--color-bg-elevated);
    border-top: 1px solid var(--color-border);
    padding: var(--space-4xl) 0 var(--space-xl);
}

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

.footer-brand p {
    color: var(--color-text-muted);
    margin-top: var(--space-md);
    max-width: 280px;
}

.footer-links h4 {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-text);
    margin-bottom: var(--space-lg);
}

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

.footer-links a {
    color: var(--color-text-muted);
    font-size: 0.9375rem;
    transition: color var(--transition-fast);
}

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

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--space-xl);
    border-top: 1px solid var(--color-border);
    font-size: 0.875rem;
    color: var(--color-text-dim);
}

.footer-legal {
    display: flex;
    gap: var(--space-lg);
}

.footer-legal a {
    color: var(--color-text-dim);
}

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

/* ========================================
   Form Styles
   ======================================== */
.form-group {
    margin-bottom: var(--space-lg);
}

.form-label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: var(--space-sm);
    color: var(--color-text);
}

.form-label .required {
    color: var(--color-primary);
}

.form-input,
.form-textarea,
.form-select {
    width: 100%;
    padding: var(--space-md);
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text);
    font-size: 1rem;
    transition: all var(--transition-fast);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(249, 115, 22, 0.1);
}

.form-input::placeholder,
.form-textarea::placeholder {
    color: var(--color-text-dim);
}

.form-textarea {
    min-height: 150px;
    resize: vertical;
}

.form-select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2371717a' stroke-width='2'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right var(--space-md) center;
    padding-right: var(--space-3xl);
}

.form-checkbox {
    display: flex;
    align-items: flex-start;
    gap: var(--space-sm);
    cursor: pointer;
}

.form-checkbox input {
    width: 20px;
    height: 20px;
    margin-top: 2px;
    accent-color: var(--color-primary);
}

.form-checkbox span {
    font-size: 0.9375rem;
    color: var(--color-text-muted);
}

.form-hint {
    font-size: 0.8125rem;
    color: var(--color-text-dim);
    margin-top: var(--space-xs);
}

.form-error {
    border-color: var(--color-error) !important;
}

.form-success {
    background: rgba(34, 197, 94, 0.1);
    border: 1px solid rgba(34, 197, 94, 0.3);
    color: var(--color-success);
    padding: var(--space-lg);
    border-radius: var(--radius-md);
    text-align: center;
    margin-bottom: var(--space-lg);
}

/* ========================================
   Page Header
   ======================================== */
.page-header {
    padding: calc(var(--header-height) + var(--space-4xl)) 0 var(--space-3xl);
    background: var(--color-bg-elevated);
    border-bottom: 1px solid var(--color-border);
    text-align: center;
}

.page-header h1 {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 800;
    margin-bottom: var(--space-md);
}

.page-header p {
    font-size: 1.125rem;
    color: var(--color-text-muted);
    max-width: 600px;
    margin: 0 auto;
}

/* ========================================
   Content Sections
   ======================================== */
.content-section {
    padding: var(--space-4xl) 0;
}

.content-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-3xl);
    align-items: start;
}

.content-card {
    background: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-2xl);
}

.content-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--space-md);
}

.content-card p {
    color: var(--color-text-muted);
}

/* ========================================
   Submission Form Page
   ======================================== */
.submission-form {
    max-width: 700px;
    margin: 0 auto;
}

.form-section {
    background: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-2xl);
    margin-bottom: var(--space-xl);
}

.form-section-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-md);
    border-bottom: 1px solid var(--color-border);
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-lg);
}

/* ========================================
   Info Cards
   ======================================== */
.info-cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-lg);
    margin-bottom: var(--space-3xl);
}

.info-card {
    background: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    text-align: center;
}

.info-card-icon {
    font-size: 2.5rem;
    margin-bottom: var(--space-md);
}

.info-card h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--space-sm);
}

.info-card p {
    font-size: 0.9375rem;
    color: var(--color-text-muted);
}

/* ========================================
   FAQ Section
   ======================================== */
.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    background: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    margin-bottom: var(--space-md);
    overflow: hidden;
}

.faq-question {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-lg);
    font-weight: 600;
    text-align: left;
    color: var(--color-text);
    transition: background var(--transition-fast);
}

.faq-question:hover {
    background: var(--color-bg-card);
}

.faq-question svg {
    flex-shrink: 0;
    transition: transform var(--transition-fast);
    color: var(--color-primary);
}

.faq-item.active .faq-question svg {
    transform: rotate(180deg);
}

.faq-answer {
    display: none;
    padding: 0 var(--space-lg) var(--space-lg);
    color: var(--color-text-muted);
}

.faq-item.active .faq-answer {
    display: block;
}

/* ========================================
   Author/Book Cards
   ======================================== */
.author-grid,
.book-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--space-xl);
}

.author-card,
.book-card {
    background: var(--color-bg-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: all var(--transition-base);
}

.author-card:hover,
.book-card:hover {
    border-color: var(--color-primary);
    transform: translateY(-4px);
}

.author-image,
.book-cover {
    width: 100%;
    aspect-ratio: 1;
    background: var(--color-bg-card);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
}

.book-cover {
    aspect-ratio: 2/3;
}

.author-info,
.book-info {
    padding: var(--space-lg);
}

.author-info h3,
.book-info h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--space-xs);
}

.author-info p,
.book-info p {
    font-size: 0.9375rem;
    color: var(--color-text-muted);
}

.book-meta {
    display: flex;
    gap: var(--space-md);
    margin-top: var(--space-sm);
    font-size: 0.8125rem;
    color: var(--color-text-dim);
}

/* ========================================
   Legal Pages
   ======================================== */
.legal-content {
    max-width: 800px;
    margin: 0 auto;
}

.legal-content h2 {
    font-size: 1.5rem;
    font-weight: 700;
    margin: var(--space-2xl) 0 var(--space-md);
}

.legal-content h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin: var(--space-xl) 0 var(--space-sm);
}

.legal-content p {
    color: var(--color-text-muted);
    margin-bottom: var(--space-md);
}

.legal-content ul {
    margin-left: var(--space-xl);
    margin-bottom: var(--space-md);
    color: var(--color-text-muted);
}

.legal-content li {
    list-style: disc;
    margin-bottom: var(--space-sm);
}

/* ========================================
   Catalog Styles
   ======================================== */
.catalog-filters {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
    justify-content: center;
    margin-bottom: var(--space-2xl);
}

.filter-btn {
    padding: var(--space-sm) var(--space-lg);
    background: transparent;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-full);
    color: var(--color-text-muted);
    font-family: var(--font-sans);
    font-size: 0.875rem;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.filter-btn:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.filter-btn.active {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--color-bg);
}

.books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--space-xl);
}

.book-cover {
    aspect-ratio: 2/3;
    background: linear-gradient(135deg, var(--color-bg-elevated), var(--color-surface));
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--space-md);
    overflow: hidden;
}

.book-placeholder {
    font-size: 4rem;
    opacity: 0.3;
}

.book-info {
    padding: 0 var(--space-sm);
}

.book-category {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-primary);
    margin-bottom: var(--space-xs);
}

.book-info h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--space-xs);
}

.book-author {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    margin-bottom: var(--space-sm);
}

.book-description {
    font-size: 0.875rem;
    color: var(--color-text-dim);
    line-height: 1.5;
}

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 1024px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: var(--space-2xl);
    }
    
    .info-cards {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: var(--header-height);
        left: 0;
        right: 0;
        background: var(--color-bg);
        border-bottom: 1px solid var(--color-border);
        flex-direction: column;
        padding: var(--space-lg);
        gap: var(--space-md);
    }
    
    .nav-links.active {
        display: flex;
    }
    
    .nav .btn {
        display: none;
    }
    
    .mobile-toggle {
        display: flex;
    }
    
    .hero-title {
        font-size: clamp(2.5rem, 10vw, 3.5rem);
    }
    
    .program-grid {
        grid-template-columns: 1fr;
        gap: var(--space-xl);
    }
    
    .program-visual {
        order: -1;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        gap: var(--space-xl);
    }
    
    .footer-bottom {
        flex-direction: column;
        gap: var(--space-md);
        text-align: center;
    }
    
    .content-grid {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .hero-buttons .btn {
        width: 100%;
    }
    
    .programs-tabs {
        flex-direction: column;
    }
    
    .tab-btn {
        width: 100%;
        justify-content: center;
    }
    
    .cta-buttons {
        flex-direction: column;
    }
    
    .cta-buttons .btn {
        width: 100%;
    }
}