@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;500;600;700;800&family=Plus+Jakarta+Sans:wght@300;400;500;600;700;800&display=swap');

:root {
    --bg-dark: #070a13;
    --bg-darker: #030509;
    --bg-card: rgba(13, 20, 38, 0.5);
    
    --neon-blue: #00f2fe;
    --neon-blue-glow: rgba(0, 242, 254, 0.35);
    --neon-purple: #b5179e;
    --neon-purple-glow: rgba(181, 23, 158, 0.35);
    --neon-pink: #f72585;
    --neon-pink-glow: rgba(247, 37, 133, 0.35);
    --neon-green: #06d6a0;
    --neon-green-glow: rgba(6, 214, 160, 0.35);
    --neon-orange: #ff9f1c;
    
    --text-white: #ffffff;
    --text-light: #e2e8f0;
    --text-muted: #94a3b8;
    
    --glass-border: rgba(255, 255, 255, 0.07);
    --glass-border-hover: rgba(0, 242, 254, 0.3);
    
    --font-header: 'Outfit', sans-serif;
    --font-body: 'Plus Jakarta Sans', sans-serif;
    
    --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Light Mode Variables */
[data-theme="light"] {
    --bg-dark: #f8fafc;
    --bg-darker: #f1f5f9;
    --bg-card: rgba(255, 255, 255, 0.75);
    
    --neon-blue: #0284c7;
    --neon-blue-glow: rgba(2, 132, 199, 0.2);
    --neon-purple: #7e22ce;
    --neon-purple-glow: rgba(126, 34, 206, 0.2);
    --neon-pink: #db2777;
    --neon-pink-glow: rgba(219, 39, 119, 0.2);
    --neon-green: #15803d;
    --neon-green-glow: rgba(21, 128, 61, 0.2);
    
    --text-white: #0f172a;
    --text-light: #1e293b;
    --text-muted: #64748b;
    
    --glass-border: rgba(15, 23, 42, 0.08);
    --glass-border-hover: rgba(2, 132, 199, 0.4);
}

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

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--bg-dark);
    color: var(--text-light);
    font-family: var(--font-body);
    overflow-x: hidden;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* Particles Background */
#particle-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    pointer-events: none;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}
::-webkit-scrollbar-track {
    background: var(--bg-darker);
}
::-webkit-scrollbar-thumb {
    background: var(--glass-border);
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--neon-blue);
    box-shadow: 0 0 10px var(--neon-blue-glow);
}

/* Base layout classes */
.container {
    width: 100%;
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Header & Navbar */
header {
    background: rgba(var(--bg-dark), 0.7);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--glass-border);
    position: sticky;
    top: 0;
    z-index: 100;
    transition: background var(--transition-normal), border-bottom var(--transition-normal);
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 80px;
}

.logo-container {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
}

.logo-icon {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--neon-blue), var(--neon-purple));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    box-shadow: 0 0 15px var(--neon-blue-glow);
    animation: rotateAtom 6s linear infinite;
}

.logo-icon::before {
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    border: 2px dashed rgba(255, 255, 255, 0.4);
    border-radius: 50%;
    animation: orbitSpin 4s linear infinite;
}

.logo-text {
    font-family: var(--font-header);
    font-weight: 800;
    font-size: 1.5rem;
    background: linear-gradient(to right, var(--neon-blue), var(--neon-purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.5px;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    list-style: none;
}

.nav-link {
    text-decoration: none;
    color: var(--text-light);
    font-weight: 500;
    font-size: 0.95rem;
    transition: var(--transition-fast);
    padding: 0.5rem 0.75rem;
    border-radius: 6px;
    border: 1px solid transparent;
}

.nav-link:hover, .nav-link.active {
    color: var(--neon-blue);
    text-shadow: 0 0 8px var(--neon-blue-glow);
    border: 1px solid var(--glass-border);
    background: rgba(0, 242, 254, 0.05);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

/* Theme Toggle */
.theme-btn {
    background: transparent;
    border: 1px solid var(--glass-border);
    color: var(--text-light);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-normal);
}

.theme-btn:hover {
    border-color: var(--neon-blue);
    box-shadow: 0 0 10px var(--neon-blue-glow);
    color: var(--neon-blue);
}

/* Buttons */
.btn {
    font-family: var(--font-header);
    font-weight: 600;
    text-decoration: none;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition-normal);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    border: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--neon-blue), var(--neon-purple));
    color: #ffffff;
    box-shadow: 0 4px 20px rgba(0, 242, 254, 0.25);
    position: relative;
    overflow: hidden;
}

.btn-primary::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: 0.5s;
}

.btn-primary:hover::before {
    left: 100%;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 25px rgba(0, 242, 254, 0.45);
}

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

.btn-secondary:hover {
    border-color: var(--neon-blue);
    background: rgba(0, 242, 254, 0.05);
    color: var(--neon-blue);
    box-shadow: 0 0 15px var(--neon-blue-glow);
}

/* Glass Card */
.glass-card {
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 2rem;
    transition: var(--transition-normal);
}

.glass-card:hover {
    border-color: var(--glass-border-hover);
    box-shadow: 0 10px 30px rgba(0, 242, 254, 0.08);
    transform: translateY(-2px);
}

/* Hero Section */
.hero {
    padding: 6rem 0 4rem;
    position: relative;
    text-align: center;
}

.hero-tag {
    font-family: var(--font-header);
    background: rgba(0, 242, 254, 0.08);
    border: 1px solid var(--neon-blue-glow);
    color: var(--neon-blue);
    padding: 0.5rem 1.25rem;
    border-radius: 50px;
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    display: inline-block;
    margin-bottom: 1.5rem;
    box-shadow: 0 0 15px rgba(0, 242, 254, 0.1);
}

.hero h1 {
    font-family: var(--font-header);
    font-size: 3.8rem;
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    background: linear-gradient(135deg, #ffffff 40%, var(--neon-blue) 70%, var(--neon-purple) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -1px;
}

[data-theme="light"] .hero h1 {
    background: linear-gradient(135deg, #0f172a 40%, var(--neon-blue) 70%, var(--neon-purple) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.2rem;
    color: var(--text-muted);
    max-width: 680px;
    margin: 0 auto 2.5rem;
    line-height: 1.6;
}

.hero-actions {
    display: flex;
    justify-content: center;
    gap: 1rem;
}

/* Sections */
section {
    padding: 4rem 0;
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-title {
    font-family: var(--font-header);
    font-size: 2.25rem;
    font-weight: 800;
    color: var(--text-white);
    margin-bottom: 1rem;
}

.section-desc {
    color: var(--text-muted);
    font-size: 1.1rem;
    max-width: 580px;
    margin: 0 auto;
}

/* Grid of Cards */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.feature-card {
    position: relative;
    overflow: hidden;
}

.feature-icon {
    width: 60px;
    height: 60px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    background: rgba(0, 242, 254, 0.08);
    border: 1px solid var(--neon-blue-glow);
    color: var(--neon-blue);
    box-shadow: 0 0 15px rgba(0, 242, 254, 0.1);
}

.feature-card:nth-child(2) .feature-icon {
    background: rgba(181, 23, 158, 0.08);
    border-color: var(--neon-purple-glow);
    color: var(--neon-purple);
    box-shadow: 0 0 15px rgba(181, 23, 158, 0.1);
}

.feature-card:nth-child(3) .feature-icon {
    background: rgba(6, 214, 160, 0.08);
    border-color: var(--neon-green-glow);
    color: var(--neon-green);
    box-shadow: 0 0 15px rgba(6, 214, 160, 0.1);
}

.feature-card:nth-child(4) .feature-icon {
    background: rgba(247, 37, 133, 0.08);
    border-color: var(--neon-pink-glow);
    color: var(--neon-pink);
    box-shadow: 0 0 15px rgba(247, 37, 133, 0.1);
}

.feature-title {
    font-family: var(--font-header);
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--text-white);
    margin-bottom: 0.75rem;
}

.feature-text {
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.feature-link {
    text-decoration: none;
    color: var(--neon-blue);
    font-family: var(--font-header);
    font-weight: 600;
    font-size: 0.9rem;
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    transition: var(--transition-fast);
}

.feature-link:hover {
    gap: 0.5rem;
    text-shadow: 0 0 8px var(--neon-blue-glow);
}

/* Sidebar Layout */
.layout-with-sidebar {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 2.5rem;
    align-items: start;
    padding: 3rem 0 6rem;
}

.sidebar {
    position: sticky;
    top: 110px;
    max-height: calc(100vh - 140px);
    overflow-y: auto;
}

.sidebar-title {
    font-family: var(--font-header);
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-white);
    margin-bottom: 1.25rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--glass-border);
}

.sidebar-menu {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.sidebar-link {
    text-decoration: none;
    color: var(--text-light);
    font-size: 0.9rem;
    padding: 0.75rem 1rem;
    border-radius: 8px;
    border: 1px solid transparent;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    transition: var(--transition-fast);
}

.sidebar-link:hover, .sidebar-link.active {
    background: rgba(0, 242, 254, 0.05);
    border-color: var(--glass-border-hover);
    color: var(--neon-blue);
    box-shadow: 0 0 10px rgba(0, 242, 254, 0.05);
}

.sidebar-link-num {
    font-family: var(--font-header);
    font-size: 0.8rem;
    font-weight: 700;
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-muted);
    width: 24px;
    height: 24px;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.sidebar-link.active .sidebar-link-num {
    background: var(--neon-blue);
    color: #ffffff;
}

/* Detail view template */
.detail-content {
    display: flex;
    flex-direction: column;
    gap: 2.5rem;
}

.detail-header {
    margin-bottom: 1rem;
}

.detail-category {
    font-family: var(--font-header);
    color: var(--neon-purple);
    font-size: 0.85rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 0.5rem;
}

.detail-title {
    font-family: var(--font-header);
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--text-white);
    line-height: 1.2;
}

/* Tabs */
.tabs-container {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.tabs-nav {
    display: flex;
    border-bottom: 1px solid var(--glass-border);
    gap: 0.5rem;
    overflow-x: auto;
}

.tab-btn {
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-family: var(--font-header);
    font-weight: 600;
    font-size: 1rem;
    padding: 1rem 1.5rem;
    cursor: pointer;
    border-bottom: 2px solid transparent;
    transition: var(--transition-normal);
    white-space: nowrap;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.tab-btn.active {
    color: var(--neon-blue);
    border-bottom-color: var(--neon-blue);
    text-shadow: 0 0 10px var(--neon-blue-glow);
}

.tab-pane {
    display: none;
    animation: fadeIn var(--transition-normal);
}

.tab-pane.active {
    display: block;
}

/* Education content typography */
.edu-text-block {
    line-height: 1.8;
    color: var(--text-light);
    font-size: 1.05rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.edu-text-block p {
    text-align: justify;
}

.edu-quote {
    border-left: 3px solid var(--neon-blue);
    background: rgba(0, 242, 254, 0.02);
    padding: 1.25rem 1.5rem;
    border-radius: 0 8px 8px 0;
    font-style: italic;
    color: var(--text-light);
}

/* Interactive Test Component */
.test-box {
    margin-top: 1.5rem;
}

.test-title {
    font-family: var(--font-header);
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--text-white);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.test-question {
    font-weight: 600;
    font-size: 1.1rem;
    margin-bottom: 1.25rem;
    color: var(--text-white);
}

.test-options {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.test-option {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--glass-border);
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition-fast);
}

.test-option:hover {
    border-color: var(--neon-blue-glow);
    background: rgba(0, 242, 254, 0.02);
}

.test-option.selected {
    border-color: var(--neon-blue);
    background: rgba(0, 242, 254, 0.06);
}

.test-option-circle {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    border: 2px solid var(--text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-fast);
}

.test-option.selected .test-option-circle {
    border-color: var(--neon-blue);
    background: var(--neon-blue);
}

.test-option-circle::after {
    content: '';
    width: 8px;
    height: 8px;
    background: #ffffff;
    border-radius: 50%;
    display: none;
}

.test-option.selected .test-option-circle::after {
    display: block;
}

.test-feedback {
    padding: 1rem 1.25rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    display: none;
    font-weight: 500;
}

.test-feedback.correct {
    display: block;
    background: rgba(6, 214, 160, 0.1);
    border: 1px solid var(--neon-green);
    color: var(--neon-green);
}

.test-feedback.wrong {
    display: block;
    background: rgba(247, 37, 133, 0.1);
    border: 1px solid var(--neon-pink);
    color: var(--neon-pink);
}

/* Virtual Simulator UI */
.simulator-container {
    background: var(--bg-card);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 2rem;
    margin-top: 1rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2.5rem;
}

.sim-controls {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.sim-control-group {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.sim-control-label {
    font-family: var(--font-header);
    font-weight: 600;
    color: var(--text-white);
    display: flex;
    justify-content: space-between;
}

.sim-control-value {
    color: var(--neon-blue);
    font-weight: 700;
}

.sim-slider {
    -webkit-appearance: none;
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: var(--glass-border);
    outline: none;
    transition: var(--transition-fast);
}

.sim-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--neon-blue);
    box-shadow: 0 0 10px var(--neon-blue-glow);
    cursor: pointer;
    transition: var(--transition-fast);
}

.sim-slider::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

.sim-visual {
    background: var(--bg-darker);
    border-radius: 12px;
    border: 1px solid var(--glass-border);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
    position: relative;
    overflow: hidden;
}

.bulb-container {
    position: relative;
    width: 100px;
    height: 100px;
}

.bulb {
    width: 80px;
    height: 80px;
    background: #475569;
    border-radius: 50%;
    position: absolute;
    top: 0;
    left: 10px;
    transition: background var(--transition-fast), box-shadow var(--transition-fast);
}

.bulb-glow {
    position: absolute;
    width: 120px;
    height: 120px;
    background: radial-gradient(circle, var(--neon-blue-glow) 0%, transparent 70%);
    top: -20px;
    left: -10px;
    opacity: 0;
    border-radius: 50%;
    pointer-events: none;
    transition: opacity var(--transition-fast);
}

.bulb-base {
    width: 40px;
    height: 30px;
    background: #94a3b8;
    position: absolute;
    bottom: 0;
    left: 30px;
    border-radius: 0 0 4px 4px;
}

.meters {
    display: flex;
    gap: 2rem;
    width: 100%;
}

.meter {
    flex: 1;
    background: var(--bg-card);
    border: 1px solid var(--glass-border);
    border-radius: 8px;
    padding: 1rem;
    text-align: center;
}

.meter-title {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
    margin-bottom: 0.25rem;
}

.meter-val {
    font-family: var(--font-header);
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--text-white);
}

/* PDF viewer placeholder */
.pdf-viewer-box {
    background: var(--bg-darker);
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    height: 480px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
}

/* Accordion FAQ */
.faq-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    overflow: hidden;
    background: var(--bg-card);
    transition: var(--transition-normal);
}

.faq-question {
    padding: 1.5rem;
    font-family: var(--font-header);
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--text-white);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    user-select: none;
}

.faq-question:hover {
    color: var(--neon-blue);
}

.faq-answer {
    padding: 0 1.5rem;
    max-height: 0;
    overflow: hidden;
    color: var(--text-muted);
    line-height: 1.7;
    transition: max-height var(--transition-normal) ease-out, padding var(--transition-normal);
}

.faq-item.active {
    border-color: var(--glass-border-hover);
    box-shadow: 0 4px 20px rgba(0, 242, 254, 0.05);
}

.faq-item.active .faq-answer {
    padding: 0 1.5rem 1.5rem;
    max-height: 200px;
}

.faq-icon {
    font-size: 1.25rem;
    transition: var(--transition-normal);
}

.faq-item.active .faq-icon {
    transform: rotate(45px);
    color: var(--neon-blue);
}

/* Contact / Feedback Form */
.contact-grid {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 4rem;
    padding: 3rem 0;
}

.contact-form-container {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-label {
    font-family: var(--font-header);
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-white);
}

.form-input {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--glass-border);
    border-radius: 8px;
    padding: 0.85rem 1rem;
    color: #ffffff;
    font-family: var(--font-body);
    font-size: 0.95rem;
    transition: var(--transition-fast);
    outline: none;
}

.form-input:focus {
    border-color: var(--neon-blue);
    box-shadow: 0 0 10px var(--neon-blue-glow);
}

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

.contact-info-container {
    display: flex;
    flex-direction: column;
    gap: 2.5rem;
}

.contact-info-item {
    display: flex;
    gap: 1.25rem;
}

.contact-info-icon {
    width: 50px;
    height: 50px;
    background: rgba(0, 242, 254, 0.08);
    border: 1px solid var(--neon-blue-glow);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--neon-blue);
    font-size: 1.2rem;
    flex-shrink: 0;
}

.contact-info-title {
    font-family: var(--font-header);
    font-weight: 700;
    color: var(--text-white);
    font-size: 1.1rem;
    margin-bottom: 0.25rem;
}

.contact-info-text {
    color: var(--text-muted);
    line-height: 1.5;
}

/* Book shelf literature UI */
.shelf-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 3rem 2rem;
    padding: 2rem 0;
}

.book-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    text-decoration: none;
    color: inherit;
}

.book-spine {
    width: 140px;
    height: 200px;
    background: linear-gradient(135deg, #1e3a8a, #3b82f6);
    border-radius: 4px 12px 12px 4px;
    box-shadow: 5px 5px 15px rgba(0,0,0,0.4);
    position: relative;
    transition: var(--transition-normal);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1.25rem;
    overflow: hidden;
    margin-bottom: 1rem;
}

.book-spine::after {
    content: '';
    position: absolute;
    left: 8px;
    top: 0;
    width: 4px;
    height: 100%;
    background: rgba(255,255,255,0.15);
}

.book-card:hover .book-spine {
    transform: translateY(-8px) rotate(-3px);
    box-shadow: 10px 15px 25px rgba(0, 242, 254, 0.2);
}

.book-title-on-cover {
    color: #ffffff;
    font-family: var(--font-header);
    font-size: 0.85rem;
    font-weight: 700;
    line-height: 1.3;
}

.book-title {
    font-family: var(--font-header);
    font-weight: 700;
    font-size: 1rem;
    color: var(--text-white);
    margin-bottom: 0.25rem;
}

.book-author {
    color: var(--text-muted);
    font-size: 0.8rem;
}

/* Literature listing text */
.literature-list-box {
    margin-top: 4rem;
    line-height: 1.8;
}

/* Auth forms */
.auth-container {
    max-width: 440px;
    margin: 5rem auto;
    width: 100%;
}

.auth-header {
    text-align: center;
    margin-bottom: 2rem;
}

.auth-title {
    font-family: var(--font-header);
    font-size: 2rem;
    font-weight: 800;
    color: var(--text-white);
    margin-bottom: 0.5rem;
}

.auth-subtitle {
    color: var(--text-muted);
}

.auth-links {
    text-align: center;
    margin-top: 1.5rem;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.auth-link-a {
    color: var(--neon-blue);
    text-decoration: none;
    font-weight: 600;
}

.auth-link-a:hover {
    text-decoration: underline;
    text-shadow: 0 0 5px var(--neon-blue-glow);
}

/* Footer */
footer {
    margin-top: auto;
    background: var(--bg-darker);
    border-top: 1px solid var(--glass-border);
    padding: 3rem 0;
    transition: background-color var(--transition-normal);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-text {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.social-links {
    display: flex;
    gap: 1rem;
}

.social-link {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid var(--glass-border);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    text-decoration: none;
    transition: var(--transition-normal);
}

.social-link:hover {
    border-color: var(--neon-blue);
    color: var(--neon-blue);
    box-shadow: 0 0 10px var(--neon-blue-glow);
    transform: translateY(-2px);
}

/* Animations */
@keyframes rotateAtom {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@keyframes orbitSpin {
    0% { transform: rotate(360deg); }
    100% { transform: rotate(0deg); }
}

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

/* Responsive queries */
@media (max-width: 968px) {
    .layout-with-sidebar {
        grid-template-columns: 1fr;
    }
    .sidebar {
        position: static;
        max-height: none;
    }
    .contact-grid {
        grid-template-columns: 1fr;
        gap: 3rem;
    }
    .simulator-container {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .navbar {
        height: 70px;
    }
    .nav-menu {
        display: none; /* In a real mobile menu this will slide out, we'll keep it simple for mock or toggle */
    }
    .hero h1 {
        font-size: 2.5rem;
    }
    .footer-content {
        flex-direction: column;
        gap: 1.5rem;
        text-align: center;
    }
}


/* Messages / Alerts */
.messages-container {
    max-width: 480px;
    margin: 1.5rem auto 0;
    padding: 0 1rem;
}

.alert {
    padding: 0.85rem 1.2rem;
    border-radius: 10px;
    margin-bottom: 0.75rem;
    font-size: 0.95rem;
    font-weight: 500;
}

.alert-error {
    background: rgba(239, 68, 68, 0.15);
    border: 1px solid rgba(239, 68, 68, 0.4);
    color: #fca5a5;
}

.alert-success {
    background: rgba(34, 197, 94, 0.15);
    border: 1px solid rgba(34, 197, 94, 0.4);
    color: #86efac;
}

/* Profile Dropdown */
.profile-dropdown {
    position: relative;
}

.profile-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 50px;
    padding: 0.4rem 0.85rem 0.4rem 0.4rem;
    cursor: pointer;
    color: var(--text-primary);
    font-size: 0.9rem;
    transition: background 0.2s;
}

.profile-btn:hover {
    background: rgba(255, 255, 255, 0.14);
}

.profile-avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--neon-blue), var(--neon-purple));
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.85rem;
    color: #fff;
    flex-shrink: 0;
}

.profile-avatar-lg {
    width: 42px;
    height: 42px;
    font-size: 1rem;
}

.profile-name {
    max-width: 110px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.profile-menu {
    display: none;
    position: absolute;
    top: calc(100% + 10px);
    right: 0;
    min-width: 240px;
    background: var(--card-bg);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 14px;
    padding: 0.5rem;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
    z-index: 1000;
}

.profile-menu.open {
    display: block;
}

.profile-menu-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.6rem 0.75rem;
}

.profile-menu-name {
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--text-primary);
}

.profile-menu-email {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 2px;
}

.profile-menu-divider {
    height: 1px;
    background: rgba(255, 255, 255, 0.08);
    margin: 0.4rem 0;
}

.profile-menu-item {
    display: flex;
    align-items: center;
    gap: 0.65rem;
    padding: 0.6rem 0.75rem;
    border-radius: 9px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: background 0.15s, color 0.15s;
}

.profile-menu-item:hover {
    background: rgba(255, 255, 255, 0.07);
    color: var(--text-primary);
}

.profile-menu-logout {
    color: #f87171;
}

.profile-menu-logout:hover {
    background: rgba(239, 68, 68, 0.1);
    color: #fca5a5;
}

.btn-nav {
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
}

.edu-quote-method {
    border-left-color: var(--neon-purple);
    background: rgba(181, 23, 158, 0.02);
    font-style: normal;
    white-space: pre-line;
}

/* ========== CURRICULUM LIST (lectures.html) ========== */
.curriculum-legend {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    padding: 1rem 1.5rem;
    background: var(--bg-card);
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}
.legend-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
    color: var(--text-muted);
}
.legend-sep {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-left: auto;
    font-style: italic;
}

.step-badge {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    border-radius: 6px;
    font-size: 0.75rem;
    font-weight: 800;
    font-family: var(--font-header);
    flex-shrink: 0;
}
.step-badge.step-lec   { background: var(--neon-blue);   color: #000; }
.step-badge.step-prac  { background: var(--neon-purple); color: #fff; }
.step-badge.step-lab   { background: var(--neon-green);  color: #000; }
.step-badge.step-indep { background: var(--neon-orange); color: #000; font-size: 0.65rem; width: 36px; }

.curriculum-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.curriculum-row {
    display: grid;
    grid-template-columns: 56px 1fr auto auto;
    align-items: center;
    gap: 1rem;
    padding: 1.1rem 1.5rem;
    background: var(--bg-card);
    border: 1px solid var(--glass-border);
    border-radius: 14px;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}
.curriculum-row:hover:not(.curriculum-row-locked) {
    border-color: var(--glass-border-hover);
    box-shadow: 0 0 18px rgba(0, 242, 254, 0.06);
}
.curriculum-row-locked {
    opacity: 0.55;
}

.curriculum-row-num {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
}
.topic-num {
    font-family: var(--font-header);
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--text-white);
    line-height: 1;
}
.topic-all-done { font-size: 1rem; color: var(--neon-green); }
.topic-lock-icon { font-size: 0.9rem; }

.curriculum-topic-name {
    font-family: var(--font-header);
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-white);
    line-height: 1.4;
}

.curriculum-steps {
    display: flex;
    gap: 0.6rem;
    flex-wrap: wrap;
}
.step-card {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.4rem 0.8rem;
    border-radius: 8px;
    font-size: 0.8rem;
    font-weight: 600;
    text-decoration: none;
    border: 1px solid var(--glass-border);
    color: var(--text-muted);
    transition: all var(--transition-fast);
    cursor: pointer;
}
.step-card:hover:not(.step-locked):not(.step-noclick) {
    border-color: var(--glass-border-hover);
    color: var(--text-white);
    transform: translateY(-1px);
}
.step-card.step-done {
    border-color: var(--neon-green);
    background: rgba(6, 214, 160, 0.08);
    color: var(--neon-green);
}
.step-card.step-open {
    border-color: var(--neon-blue);
    color: var(--neon-blue);
}
.step-card.step-locked, .step-card.step-noclick {
    pointer-events: none;
    opacity: 0.5;
}
.step-label { font-size: 0.8rem; }
.step-check { color: var(--neon-green); font-size: 0.85rem; }
.step-lock  { font-size: 0.75rem; }

.locked-hint {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-style: italic;
}

.curriculum-independent {
    border-left: 3px solid var(--neon-orange);
}

/* ========== SIDEBAR SECTIONS ========== */
.sidebar-section {
    margin-bottom: 0.25rem;
}
.sidebar-section-toggle {
    width: 100%;
    display: flex;
    align-items: center;
    gap: 0.6rem;
    padding: 0.75rem 1rem;
    background: rgba(255,255,255,0.03);
    border: 1px solid var(--glass-border);
    border-radius: 10px;
    cursor: pointer;
    font-family: var(--font-header);
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--text-light);
    text-align: left;
    transition: background var(--transition-fast);
    text-decoration: none;
}
.sidebar-section-toggle:hover {
    background: rgba(0,242,254,0.05);
    border-color: var(--glass-border-hover);
}
.sidebar-section-icon { font-size: 1rem; }
.sidebar-section-arrow {
    margin-left: auto;
    font-size: 0.75rem;
    transition: transform var(--transition-fast);
}
.sidebar-section.collapsed .sidebar-section-arrow { transform: rotate(-90deg); }
.sidebar-section.collapsed .sidebar-section-body { display: none; }
.sidebar-section-link { display: flex; }

.sidebar-section-body {
    margin-top: 0.25rem;
    padding-left: 0.5rem;
}

.sidebar-link-done   { border-left: 2px solid var(--neon-green) !important; }
.sidebar-link-locked { opacity: 0.45; pointer-events: none; }
.sidebar-done-mark   { color: var(--neon-green); font-size: 0.8rem; margin-left: auto; }
.sidebar-lock-mark   { font-size: 0.75rem; margin-left: auto; }
.sidebar-link-text   { flex: 1; line-height: 1.3; }

.sidebar-link-num.sidebar-step-lec   { background: var(--neon-blue)!important;   color: #000; }
.sidebar-link-num.sidebar-step-prac  { background: var(--neon-purple)!important; color: #fff; }
.sidebar-link-num.sidebar-step-lab   { background: var(--neon-green)!important;  color: #000; }

/* ========== TOPIC PROGRESS STEPS (top of detail page) ========== */
.topic-progress-bar-wrap {
    margin-bottom: 1.25rem;
}
.topic-progress-steps {
    display: flex;
    align-items: center;
    gap: 0;
}
.tps-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.3rem;
    min-width: 90px;
}
.tps-dot {
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--glass-border);
    border: 2px solid var(--text-muted);
    transition: all var(--transition-normal);
}
.tps-item.tps-done .tps-dot {
    background: var(--neon-green);
    border-color: var(--neon-green);
    box-shadow: 0 0 8px var(--neon-green-glow);
}
.tps-item.tps-active .tps-dot {
    background: var(--neon-blue);
    border-color: var(--neon-blue);
    box-shadow: 0 0 8px var(--neon-blue-glow);
}
.tps-label {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-family: var(--font-header);
    font-weight: 600;
}
.tps-item.tps-done .tps-label   { color: var(--neon-green); }
.tps-item.tps-active .tps-label { color: var(--neon-blue); }
.tps-line {
    flex: 1;
    height: 2px;
    background: var(--glass-border);
    margin-bottom: 1.1rem;
    transition: background var(--transition-normal);
}
.tps-line.tps-line-done { background: var(--neon-green); }

/* ========== MAIN SECTION TABS ========== */
.tab-btn.tab-locked {
    opacity: 0.5;
    cursor: not-allowed;
}
.tab-btn.tab-locked:hover {
    background: transparent;
    color: var(--text-muted);
    border-color: var(--glass-border);
}

/* ========== SUB-TABS ========== */
.subtabs-container {
    margin-bottom: 0;
}
.subtabs-nav {
    flex-wrap: wrap;
    gap: 0.4rem;
}
.subtabs-nav .tab-btn {
    font-size: 0.8rem;
    padding: 0.5rem 0.9rem;
}

/* ========== COMPLETION BUTTON ========== */
.complete-section {
    display: flex;
    justify-content: center;
    padding: 1.5rem 0 0.5rem;
}
.complete-section.complete-done {
    font-family: var(--font-header);
    font-size: 0.95rem;
    color: var(--neon-green);
    font-weight: 700;
    gap: 0.5rem;
    border-top: 1px solid var(--glass-border);
    margin-top: 1rem;
}
.btn-complete {
    background: linear-gradient(135deg, rgba(6, 214, 160, 0.15), rgba(0, 242, 254, 0.1));
    border: 1px solid var(--neon-green);
    color: var(--neon-green);
    padding: 0.75rem 2rem;
    border-radius: 10px;
    font-family: var(--font-header);
    font-size: 0.95rem;
    font-weight: 700;
    cursor: pointer;
    transition: all var(--transition-fast);
}
.btn-complete:hover {
    background: rgba(6, 214, 160, 0.25);
    box-shadow: 0 0 20px rgba(6, 214, 160, 0.3);
    transform: translateY(-1px);
}
.btn-complete:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.btn-next-step {
    background: linear-gradient(135deg, rgba(0, 242, 254, 0.15), rgba(181, 23, 158, 0.1));
    border: 1px solid var(--neon-blue);
    color: var(--neon-blue);
    padding: 0.7rem 1.8rem;
    border-radius: 10px;
    font-family: var(--font-header);
    font-size: 0.95rem;
    font-weight: 700;
    cursor: pointer;
    transition: all var(--transition-fast);
    animation: glowPulse 1.5s ease-in-out infinite;
}
.btn-next-step:hover {
    background: rgba(0, 242, 254, 0.25);
    box-shadow: 0 0 24px rgba(0, 242, 254, 0.35);
    transform: translateX(4px);
}
@keyframes glowPulse {
    0%, 100% { box-shadow: 0 0 8px rgba(0, 242, 254, 0.2); }
    50%       { box-shadow: 0 0 20px rgba(0, 242, 254, 0.5); }
}

.complete-section.complete-done {
    gap: 1rem;
    flex-wrap: wrap;
    justify-content: center;
}

/* ========== LOCK OVERLAY ========== */
.lock-overlay {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 320px;
    border: 1px dashed var(--glass-border);
    border-radius: 16px;
    background: rgba(0,0,0,0.15);
}
.lock-overlay-inner {
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    padding: 2rem;
}
.lock-big-icon {
    font-size: 3.5rem;
    opacity: 0.6;
    animation: pulse 2s ease-in-out infinite;
}
.lock-overlay-inner h3 {
    font-family: var(--font-header);
    font-size: 1.4rem;
    color: var(--text-white);
    margin: 0;
}
.lock-overlay-inner p {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin: 0;
    max-width: 300px;
    line-height: 1.6;
}
@keyframes pulse {
    0%, 100% { opacity: 0.6; transform: scale(1); }
    50%       { opacity: 1;   transform: scale(1.08); }
}

/* ========== RESPONSIVE ========== */
@media (max-width: 900px) {
    .curriculum-row {
        grid-template-columns: 44px 1fr;
        grid-template-rows: auto auto auto;
    }
    .curriculum-steps    { grid-column: 1 / -1; }
    .curriculum-row-action { grid-column: 1 / -1; }
    .curriculum-row-name { grid-column: 2; }
}
@media (max-width: 600px) {
    .topic-progress-steps { gap: 0; overflow-x: auto; }
    .tps-item { min-width: 70px; }
}

/* ── REVIEW WIDGET ──────────────────────────────────────────────── */
.review-widget { padding: 0; overflow: hidden; }

.review-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1.25rem 1.5rem;
    background: rgba(0, 242, 254, 0.04);
    border-bottom: 1px solid var(--glass-border);
    flex-wrap: wrap;
}

.review-timer-wrap {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex: 1;
}

.review-timer {
    font-family: var(--font-header);
    font-size: 2rem;
    font-weight: 800;
    color: var(--neon-blue);
    letter-spacing: 2px;
    transition: color 0.3s;
    min-width: 5ch;
}

.review-timer.warn { color: var(--neon-pink); }

.review-meta {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.review-progress-bar {
    height: 4px;
    background: var(--glass-border);
    width: 100%;
}

.review-progress-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--neon-blue), var(--neon-purple));
    transition: width 1s linear, background 0.5s;
}

.review-progress-fill.warn {
    background: linear-gradient(90deg, var(--neon-pink), var(--neon-purple));
}

.review-questions-list {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.review-q-card {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    padding: 1.25rem;
    transition: border-color 0.3s;
}

.review-q-card.answered { border-color: var(--neon-green); }

.review-q-row {
    display: flex;
    gap: 1rem;
    align-items: flex-start;
    margin-bottom: 0.75rem;
}

.review-q-badge {
    min-width: 28px;
    height: 28px;
    border-radius: 50%;
    background: rgba(0, 242, 254, 0.12);
    color: var(--neon-blue);
    font-weight: 700;
    font-size: 0.8rem;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.review-q-text {
    color: var(--text-primary, var(--text-light));
    line-height: 1.6;
    font-size: 0.95rem;
    margin: 0;
}

.review-a-row {
    margin: 0.75rem 0;
    padding: 1rem;
    background: rgba(6, 214, 160, 0.06);
    border-left: 3px solid var(--neon-green);
    border-radius: 0 8px 8px 0;
    animation: reviewFadeIn 0.3s ease;
}

.review-a-content {
    color: var(--text-light);
    line-height: 1.7;
    font-size: 0.9rem;
    white-space: pre-line;
}

.review-user-input {
    margin: 0.5rem 0 0.25rem;
    transition: opacity 0.3s;
}

.review-textarea {
    width: 100%;
    background: rgba(0, 242, 254, 0.04);
    border: 1px solid var(--glass-border);
    border-radius: 8px;
    color: var(--text-light);
    font-family: var(--font-body);
    font-size: 0.9rem;
    padding: 0.75rem 1rem;
    resize: vertical;
    min-height: 80px;
    box-sizing: border-box;
    transition: border-color 0.2s;
}

.review-textarea:focus {
    outline: none;
    border-color: var(--neon-blue);
}

.review-textarea:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

.review-a-label {
    font-size: 0.78rem;
    color: var(--neon-green);
    font-weight: 700;
    margin-bottom: 0.3rem;
    font-family: var(--font-header);
    letter-spacing: 0.5px;
}

.review-finished-banner {
    margin: 0 1.5rem 1.5rem;
    padding: 1rem;
    background: rgba(6, 214, 160, 0.1);
    border: 1px solid var(--neon-green);
    border-radius: 10px;
    color: var(--neon-green);
    font-weight: 700;
    text-align: center;
    font-family: var(--font-header);
}

@keyframes reviewFadeIn {
    from { opacity: 0; transform: translateY(-6px); }
    to   { opacity: 1; transform: translateY(0); }
}