/* ===== TEAL/CYAN GRADIENT THEME ===== */
:root {
    /* Light Background with Teal Accents */
    --bg-primary: #f0fdfa;
    --bg-secondary: #e6f9f5;
    --bg-tertiary: #d5f5f0;
    
    /* Surface Colors - Clean & Airy */
    --surface: rgba(255, 255, 255, 0.88);
    --surface-2: rgba(255, 255, 255, 0.95);
    --surface-3: rgba(13, 148, 136, 0.04);
    
    /* Text Colors */
    --ink: #0f172a;
    --ink-light: #1e293b;
    --muted: #64748b;
    --muted-light: rgba(15, 23, 42, 0.4);
    
    /* Primary Gradient - Teal/Cyan */
    --primary-gradient: linear-gradient(135deg, #0d9488, #14b8a6);
    --primary: #0d9488;
    --primary-light: #14b8a6;
    --primary-dark: #0f766e;
    
    /* Secondary Accents */
    --secondary: #06b6d4;
    --secondary-light: #22d3ee;
    --secondary-gradient: linear-gradient(135deg, #06b6d4, #0891b2);
    
    --accent: #f59e0b;
    --accent-light: #fbbf24;
    --accent-gradient: linear-gradient(135deg, #f59e0b, #f97316);
    
    --success: #10b981;
    --success-light: #34d399;
    --success-gradient: linear-gradient(135deg, #10b981, #059669);
    
    --pink: #ec4899;
    --pink-light: #f472b6;
    --pink-gradient: linear-gradient(135deg, #ec4899, #8b5cf6);
    
    --indigo: #4f46e5;
    --indigo-light: #818cf8;
    --indigo-gradient: linear-gradient(135deg, #4f46e5, #7c3aed);
    
    /* Category Colors - Teal Themed */
    --c-ga: #0d9488;
    --c-sci: #14b8a6;
    --c-math: #06b6d4;
    --c-social: #0891b2;
    --c-eng: #0f766e;
    --c-cs: #14b8a6;
    --c-hin: #0d9488;
    
    /* Shadows - Soft & Modern */
    --shadow-sm: 0 1px 3px rgba(13, 148, 136, 0.06), 0 1px 2px rgba(13, 148, 136, 0.04);
    --shadow-md: 0 4px 20px rgba(13, 148, 136, 0.08), 0 2px 6px rgba(13, 148, 136, 0.04);
    --shadow-lg: 0 10px 40px rgba(13, 148, 136, 0.10), 0 4px 12px rgba(13, 148, 136, 0.06);
    --shadow-xl: 0 20px 60px rgba(13, 148, 136, 0.12), 0 8px 20px rgba(13, 148, 136, 0.08);
    
    --glass-border: rgba(13, 148, 136, 0.12);
    
    --radius: 14px;
    --radius-lg: 20px;
    --radius-xl: 28px;
    
    --font-display: 'Fraunces', serif;
    --font-body: 'IBM Plex Sans', sans-serif;
    --font-mono: 'IBM Plex Mono', monospace;
}

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

html {
    scroll-behavior: smooth;
}

body {
    min-height: 100vh;
    margin: 0;
    /* padding: 0 1rem; */
    background: 
        radial-gradient(ellipse at 0% 0%, rgba(13, 148, 136, 0.08) 0%, transparent 50%),
        radial-gradient(ellipse at 100% 100%, rgba(20, 184, 166, 0.06) 0%, transparent 50%),
        radial-gradient(ellipse at 50% 50%, rgba(13, 148, 136, 0.03) 0%, transparent 70%),
        linear-gradient(135deg, #f0fdfa 0%, #e6f9f5 50%, #f0fdfa 100%);
    background-attachment: fixed;
    color: var(--ink);
    font-family: var(--font-body);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    position: relative;
}

/* Subtle animated gradient overlay */
body::before {
    content: '';
    position: fixed;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: 
        radial-gradient(circle at 30% 40%, rgba(13, 148, 136, 0.05) 0%, transparent 30%),
        radial-gradient(circle at 70% 60%, rgba(20, 184, 166, 0.05) 0%, transparent 30%),
        radial-gradient(circle at 50% 80%, rgba(6, 182, 212, 0.03) 0%, transparent 25%);
    pointer-events: none;
    z-index: 0;
    animation: gradientFloat 15s ease-in-out infinite alternate;
}

@keyframes gradientFloat {
    0% { transform: translate(0, 0) rotate(0deg); }
    50% { transform: translate(2%, 1%) rotate(2deg); }
    100% { transform: translate(-1%, -1%) rotate(-2deg); }
}

/* Floating particles - Teal themed */
body::after {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        radial-gradient(3px 3px at 10% 20%, rgba(13, 148, 136, 0.15), transparent),
        radial-gradient(3px 3px at 30% 60%, rgba(20, 184, 166, 0.10), transparent),
        radial-gradient(3px 3px at 50% 10%, rgba(6, 182, 212, 0.12), transparent),
        radial-gradient(3px 3px at 70% 80%, rgba(13, 148, 136, 0.10), transparent),
        radial-gradient(3px 3px at 90% 40%, rgba(20, 184, 166, 0.12), transparent),
        radial-gradient(3px 3px at 15% 85%, rgba(6, 182, 212, 0.08), transparent),
        radial-gradient(3px 3px at 65% 30%, rgba(13, 148, 136, 0.10), transparent),
        radial-gradient(3px 3px at 45% 70%, rgba(20, 184, 166, 0.08), transparent);
    background-size: 250px 250px;
    pointer-events: none;
    z-index: 0;
    animation: floatParticles 30s linear infinite;
}

@keyframes floatParticles {
    0% { transform: translateY(0) scale(1); }
    50% { transform: translateY(-15px) scale(1.02); }
    100% { transform: translateY(0) scale(1); }
}

a {
    color: inherit;
    text-decoration: none;
}

::selection {
    background: var(--primary);
    color: #ffffff;
}

:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 3px;
    border-radius: 4px;
}

/* ===== Header ===== */
#header {
    font-family: var(--font-body);
    position: relative;
    z-index: 10;
}

#header:empty {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 18px 6vw;
    background: rgba(255, 255, 255, 0.88);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--glass-border);
    position: sticky;
    top: 0;
    z-index: 50;
    box-shadow: var(--shadow-sm);
}

#header:empty::before {
    content: "🌊 SHRESHTA";
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 1.25rem;
    letter-spacing: 0.02em;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

#header:empty::after {
    content: "📚 GA Notes";
    font-family: var(--font-mono);
    font-size: 0.72rem;
    color: var(--muted);
}

/* ===== Footer ===== */
#footer {
    font-family: var(--font-body);
    position: relative;
    z-index: 10;
}

#footer:empty {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 28px 6vw;
    margin-top: 60px;
    border-top: 1px solid var(--glass-border);
    color: var(--muted);
    font-size: 0.85rem;
    text-align: center;
    background: rgba(255, 255, 255, 0.6);
    backdrop-filter: blur(10px);
}

#footer:empty::before {
    content: "© 2026 SHRESHTA — 🌊 सफलता की ओर एक कदम";
}

/* ===== Hero Section ===== */
.hero {
    padding: 2.5rem 0 1.5rem;
    max-width: 1300px;
    margin: 0 auto;
    position: relative;
    z-index: 5;
}

.eyebrow {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
}

.eyebrow::before {
    content: "";
    width: 30px;
    height: 2px;
    background: var(--primary-gradient);
    display: inline-block;
    border-radius: 2px;
}

.hero h1 {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: clamp(1.8rem, 5.4vw, 2.8rem);
    line-height: 1.08;
    margin: 0 0 20px;
    max-width: 14ch;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero h1 em {
    font-style: italic;
    color: var(--secondary);
    -webkit-text-fill-color: var(--secondary);
}

.hero p {
    color: var(--ink-light);
    font-size: 1.05rem;
    margin: 0 0 34px;
    text-align: justify;
    max-width: 800px;
    line-height: 1.7;
    background: var(--surface);
    padding: 22px 28px;
    border-radius: var(--radius);
    border-left: 4px solid var(--primary);
    box-shadow: var(--shadow-md);
    backdrop-filter: blur(5px);
}

.hero p strong {
    color: var(--primary);
    font-weight: 600;
}

.search-wrap {
    display: flex;
    align-items: center;
    gap: 12px;
    max-width: 450px;
    background: var(--surface);
    border: 2px solid var(--glass-border);
    border-radius: 14px;
    padding: 14px 20px;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}

.search-wrap:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-md);
}

.search-wrap:focus-within {
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(13, 148, 136, 0.1), var(--shadow-md);
    transform: scale(1.01);
}

.search-wrap svg {
    flex: none;
    opacity: 0.6;
    color: var(--primary);
    transition: opacity 0.3s ease;
}

.search-wrap:focus-within svg {
    opacity: 1;
}

.search-wrap input {
    background: none;
    border: none;
    outline: none;
    color: var(--ink);
    font-family: var(--font-body);
    font-size: 0.95rem;
    width: 100%;
}

.search-wrap input::placeholder {
    color: var(--muted-light);
    font-size: 0.9rem;
}

/* Search Stats */
.search-stats {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--muted);
    margin-top: 12px;
    display: none;
    padding: 8px 16px;
    background: var(--surface);
    border-radius: 8px;
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-sm);
}

.search-stats.show {
    display: inline-block;
}

.search-stats span {
    color: var(--primary);
    font-weight: 600;
}

/* ===== Shelf Section ===== */
.shelf-section {
    max-width: 1300px;
    margin: 0 auto;
    padding: 1rem 0 2rem;
    width: 100%;
    position: relative;
    z-index: 5;
}

.shelf-section h2 {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--muted);
    margin: 0 0 24px;
    padding-bottom: 14px;
    border-bottom: 2px solid var(--glass-border);
    display: flex;
    align-items: center;
    gap: 12px;
}

.shelf-section h2::before {
    content: "📚";
    font-size: 1.2rem;
}

.shelf-section h2::after {
    content: "";
    flex: 1;
    height: 2px;
    background: linear-gradient(90deg, var(--glass-border), transparent);
}

.shelf {
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;
    gap: 20px;
    width: 100%;
    margin: 0 auto;
}

/* ===== Book Cards ===== */
.book {
    --c: var(--primary);
    --gradient-start: #ffffff;
    --gradient-end: #f0fdfa;
    
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    width: 380px;
    margin: auto;
    min-height: 220px;
    background: var(--surface);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    text-decoration: none;
    color: var(--ink);
    transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    opacity: 0;
    transform: translateY(20px);
    animation: riseIn 0.7s ease forwards;
    box-shadow: var(--shadow-sm);
}

.book::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, 
        rgba(13, 148, 136, 0.02) 0%,
        transparent 50%,
        rgba(20, 184, 166, 0.02) 100%
    );
    pointer-events: none;
    z-index: 1;
}

.book:hover,
.book:focus-visible {
    transform: translateY(-6px) scale(1.01);
    border-color: var(--c);
    box-shadow: var(--shadow-lg), 0 0 0 3px rgba(13, 148, 136, 0.08);
    background: var(--surface-2);
}

.book .spine {
    flex: none;
    order: 2;
    width: 100%;
    height: 56px;
    background: var(--primary-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-mono);
    font-weight: 600;
    font-size: 0.8rem;
    letter-spacing: 0.14em;
    color: #ffffff;
    position: relative;
    z-index: 2;
}

.book .spine span {
    writing-mode: horizontal-tb;
    transform: none;
    display: flex;
    align-items: center;
    gap: 8px;
}

.book .spine span::before {
    content: "◆";
    font-size: 0.6rem;
    opacity: 0.6;
}

.book .content {
    order: 1;
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    justify-content: flex-start;
    gap: 12px;
    padding: 24px 22px 20px;
    position: relative;
    z-index: 2;
}

.book .text h3 {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 1.25rem;
    margin: 0 0 6px;
    color: var(--ink);
    line-height: 1.3;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.book .text p {
    margin: 0;
    color: var(--muted);
    font-size: 0.9rem;
    max-width: 48ch;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
    line-height: 1.6;
}

.book .go {
    flex: none;
    margin-top: auto;
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--c);
    display: flex;
    align-items: center;
    gap: 10px;
    white-space: nowrap;
    padding: 6px 14px 6px 0;
    border-radius: 6px;
    transition: all 0.3s ease;
}

.book .go svg {
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    flex: none;
}

.book:hover .go svg,
.book:focus-visible .go svg {
    transform: translateX(6px);
}

.book .go::after {
    content: "→";
    opacity: 0;
    transform: translateX(-10px);
    transition: all 0.3s ease;
}

.book:hover .go::after,
.book:focus-visible .go::after {
    opacity: 1;
    transform: translateX(0);
}

/* Book hover glow effect */
.book::after {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at var(--mouse-x, 50%) var(--mouse-y, 50%), 
        var(--c) 0%, 
        transparent 60%
    );
    opacity: 0;
    transition: opacity 0.4s ease;
    pointer-events: none;
    z-index: 0;
}

.book:hover::after {
    opacity: 0.06;
}

/* ===== Hidden & Empty States ===== */
.book.is-hidden {
    display: none;
}

.book.match-highlight {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(13, 148, 136, 0.15), var(--shadow-md);
}

.empty-state {
    display: none;
    padding: 60px 20px;
    color: var(--muted);
    font-family: var(--font-body);
    font-size: 1rem;
    text-align: center;
    background: var(--surface);
    border-radius: var(--radius-lg);
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-sm);
}

.empty-state.show {
    display: block;
}

.empty-state span {
    color: var(--primary);
    font-weight: 600;
}

.empty-state::before {
    content: "🔍";
    display: block;
    font-size: 3rem;
    margin-bottom: 16px;
}

/* ===== Animations ===== */
@keyframes riseIn {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.book:nth-child(1) { animation-delay: 0.05s; }
.book:nth-child(2) { animation-delay: 0.10s; }
.book:nth-child(3) { animation-delay: 0.15s; }
.book:nth-child(4) { animation-delay: 0.20s; }
.book:nth-child(5) { animation-delay: 0.25s; }
.book:nth-child(6) { animation-delay: 0.30s; }
.book:nth-child(7) { animation-delay: 0.35s; }
.book:nth-child(8) { animation-delay: 0.40s; }
.book:nth-child(9) { animation-delay: 0.45s; }
.book:nth-child(10) { animation-delay: 0.50s; }
.book:nth-child(11) { animation-delay: 0.55s; }
.book:nth-child(12) { animation-delay: 0.60s; }
.book:nth-child(13) { animation-delay: 0.65s; }
.book:nth-child(14) { animation-delay: 0.70s; }
.book:nth-child(15) { animation-delay: 0.75s; }
.book:nth-child(16) { animation-delay: 0.80s; }
.book:nth-child(17) { animation-delay: 0.85s; }
.book:nth-child(18) { animation-delay: 0.90s; }
.book:nth-child(19) { animation-delay: 0.95s; }
.book:nth-child(20) { animation-delay: 1.00s; }
.book:nth-child(n+21) { animation-delay: 1.05s; }

/* ===== Scrollbar Styling ===== */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: var(--primary-gradient);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--secondary-gradient);
}

/* ===== Responsive Design ===== */
@media (max-width: 900px) {
    .hero p {
        padding: 18px 22px;
        font-size: 0.98rem;
    }
}

@media (max-width: 800px) {
    .shelf-section {
        flex-direction: row;
    }

    .shelf {
        gap: 16px;
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    }

    .book {
        flex-direction: row;
        min-width: 150px;
        width: 100%;
        flex-wrap: wrap;
        min-height: 160px;
    }

    .book .spine {
        order: 0;
        width: 60px;
        height: auto;
        min-height: 160px;
    }

    .book .spine span {
        writing-mode: vertical-rl;
        transform: rotate(180deg);
    }

    .book .spine span::before {
        content: "◆";
        font-size: 0.5rem;
        opacity: 0.6;
        transform: rotate(90deg);
    }

    .book .content {
        order: 0;
        flex: 1;
        flex-direction: row;
        align-items: center;
        justify-content: space-between;
        flex-wrap: wrap;
        gap: 14px;
        padding: 18px 18px 16px;
        min-height: 160px;
    }

    .book .text {
        flex: 1;
        min-width: 140px;
    }

    .book .text p {
        display: block;
        -webkit-line-clamp: unset;
        overflow: visible;
        font-size: 0.85rem;
    }

    .book .go {
        margin-top: 0;
        font-size: 0.72rem;
    }

    .book .text h3 {
        font-size: 1.1rem;
    }

    .hero p {
        padding: 16px 20px;
        font-size: 0.95rem;
    }
    
    .search-wrap {
        max-width: 100%;
        padding: 12px 16px;
    }
}

@media (max-width: 500px) {
    body {
        padding: 0 0.6rem;
    }

    .shelf {
        grid-template-columns: 1fr;
        gap: 14px;
    }

    .shelf .book {
        max-width: 100%;
        margin: 0;
        min-height: 140px;
    }

    .book .spine {
        width: 48px;
        min-height: 140px;
    }

    .book .content {
        padding: 14px 14px 12px;
        min-height: 140px;
        gap: 10px;
    }

    .book .text h3 {
        font-size: 1rem;
    }

    .book .text p {
        font-size: 0.8rem;
        -webkit-line-clamp: 2;
        display: -webkit-box;
    }

    .hero {
        padding: 1.5rem 0 0.5rem;
    }

    .hero p {
        padding: 14px 18px;
        font-size: 0.9rem;
        margin-bottom: 24px;
        border-left-width: 3px;
    }

    .eyebrow {
        font-size: 0.7rem;
        gap: 8px;
    }

    .eyebrow::before {
        width: 20px;
    }

    .search-wrap {
        padding: 10px 14px;
        border-radius: 10px;
    }

    .search-wrap input {
        font-size: 0.85rem;
    }

    .shelf-section h2 {
        font-size: 0.75rem;
        margin-bottom: 16px;
        padding-bottom: 10px;
    }

    #header:empty {
        padding: 12px 4vw;
    }

    #header:empty::before {
        font-size: 1rem;
    }

    #header:empty::after {
        font-size: 0.65rem;
    }

    #footer:empty {
        padding: 20px 4vw;
        font-size: 0.75rem;
        margin-top: 30px;
    }

    .empty-state {
        padding: 40px 16px;
        font-size: 0.9rem;
    }

    .empty-state::before {
        font-size: 2.5rem;
    }
}

@media (max-width: 400px) {
    body {
        overflow-x: hidden;
    }

    .shelf {
        grid-template-columns: 1fr;
        width: 100%;
    }

    .shelf .book {
        max-width: 100%;
        margin: 0;
        min-height: 120px;
    }

    .book .spine {
        width: 40px;
        min-height: 120px;
    }

    .book .spine span {
        font-size: 0.6rem;
    }

    .book .content {
        padding: 10px 12px 10px;
        min-height: 120px;
        gap: 8px;
    }

    .book .text h3 {
        font-size: 0.95rem;
    }

    .book .text p {
        font-size: 0.75rem;
        -webkit-line-clamp: 2;
    }

    .book .go {
        font-size: 0.65rem;
        padding: 4px 10px 4px 0;
    }

    .hero p {
        padding: 10px 14px;
        font-size: 0.85rem;
        border-left-width: 2px;
    }

    .search-wrap {
        padding: 8px 12px;
        border-radius: 8px;
        gap: 8px;
    }

    .search-wrap input {
        font-size: 0.8rem;
    }
}

/* ===== Loading shimmer effect ===== */
.book {
    position: relative;
    overflow: hidden;
}

.book .shimmer {
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(
        90deg,
        transparent,
        rgba(13, 148, 136, 0.04),
        transparent
    );
    animation: shimmer 3s infinite;
    pointer-events: none;
    z-index: 3;
}

@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(200%); }
}

/* ===== Utility Classes ===== */
.text-gradient {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.badge {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    background: var(--surface);
    border: 1px solid var(--glass-border);
    color: var(--muted);
}

/* ===== Gradient Border Effect ===== */
.gradient-border {
    position: relative;
    border: none;
}

.gradient-border::before {
    content: '';
    position: absolute;
    inset: -2px;
    border-radius: inherit;
    background: var(--primary-gradient);
    z-index: -1;
    opacity: 0.3;
    transition: opacity 0.3s ease;
}

.gradient-border:hover::before {
    opacity: 0.6;
}

/* ===== Teal Themed Glows ===== */
.glow-teal {
    box-shadow: 0 0 30px rgba(13, 148, 136, 0.08);
}

.glow-cyan {
    box-shadow: 0 0 30px rgba(6, 182, 212, 0.08);
}

/* ===== Category-specific colors ===== */
.book[data-category="national"] { --c: #0d9488; }
.book[data-category="culture"] { --c: #14b8a6; }
.book[data-category="sports"] { --c: #06b6d4; }
.book[data-category="defence"] { --c: #0891b2; }
.book[data-category="science"] { --c: #0f766e; }
.book[data-category="environment"] { --c: #14b8a6; }
.book[data-category="current"] { --c: #0d9488; }
.book[data-category="history"] { --c: #06b6d4; }

/* ===== Button Styles ===== */
.btn-primary {
    display: inline-block;
    padding: 10px 24px;
    background: var(--primary-gradient);
    color: #ffffff;
    border: none;
    border-radius: 10px;
    font-family: var(--font-body);
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    display: inline-block;
    padding: 10px 24px;
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
    border-radius: 10px;
    font-family: var(--font-body);
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-secondary:hover {
    background: var(--primary-gradient);
    color: #ffffff;
    border-color: transparent;
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}