/* ===== CSS RESET & BASE ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Colors */
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --secondary-color: #06b6d4;
    --secondary-dark: #0891b2;
    --accent-color: #f97316;
    --accent-dark: #ea580c;
    
    --text-color: #1e293b;
    --text-light: #64748b;
    --text-white: #ffffff;
    
    --bg-color: #ffffff;
    --bg-light: #f8fafc;
    --bg-dark: #1e293b;
    --bg-card: #ffffff;
    
    --border-color: #e2e8f0;
    --border-light: #f1f5f9;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
    
    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Layout */
    --container-max-width: 1200px;
    --header-height: 80px;
    --border-radius: 0.5rem;
    --border-radius-lg: 1rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* Dark theme variables */
[data-theme="dark"] {
    --text-color: #f1f5f9;
    --text-light: #94a3b8;
    --bg-color: #0f172a;
    --bg-light: #1e293b;
    --bg-card: #334155;
    --border-color: #475569;
    --border-light: #334155;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* ===== UTILITY CLASSES ===== */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.section {
    padding: var(--spacing-3xl) 0;
}

.section__header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section__title {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section__subtitle {
    font-size: var(--font-size-lg);
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto;
}

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

.bg-light {
    background-color: var(--bg-light);
}

/* ===== BUTTONS ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    text-decoration: none;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all var(--transition-normal);
    white-space: nowrap;
}

.btn--primary {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--text-white);
    box-shadow: var(--shadow-md);
}

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

.btn--secondary {
    background-color: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

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

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

/* ===== HEADER ===== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--header-height);
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-light);
    z-index: 1000;
    transition: all var(--transition-normal);
}

[data-theme="dark"] .header {
    background-color: rgba(15, 23, 42, 0.95);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.nav__brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    color: var(--primary-color);
    text-decoration: none;
}

.nav__icon {
    font-size: var(--font-size-2xl);
}

.nav__menu {
    display: flex;
    align-items: center;
}

.nav__list {
    display: flex;
    list-style: none;
    gap: var(--spacing-xl);
}

.nav__link {
    font-weight: var(--font-weight-medium);
    color: var(--text-color);
    text-decoration: none;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius);
    transition: all var(--transition-normal);
    position: relative;
}

.nav__link:hover,
.nav__link.active {
    color: var(--primary-color);
}

.nav__link.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 50%;
    transform: translateX(-50%);
    width: 20px;
    height: 2px;
    background-color: var(--primary-color);
    border-radius: 1px;
}

.nav__actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.theme-toggle {
    background: none;
    border: none;
    color: var(--text-color);
    font-size: var(--font-size-lg);
    cursor: pointer;
    padding: var(--spacing-sm);
    border-radius: var(--border-radius);
    transition: all var(--transition-normal);
}

.theme-toggle:hover {
    background-color: var(--bg-light);
    color: var(--primary-color);
}

.nav__toggle,
.nav__close {
    display: none;
    background: none;
    border: none;
    font-size: var(--font-size-xl);
    cursor: pointer;
    color: var(--text-color);
}

/* ===== HERO SECTION ===== */
.hero {
    padding-top: calc(var(--header-height) + var(--spacing-3xl));
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.05), rgba(6, 182, 212, 0.05));
}

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

.hero__title {
    font-size: var(--font-size-5xl);
    font-weight: var(--font-weight-bold);
    line-height: 1.2;
    margin-bottom: var(--spacing-lg);
}

.hero__description {
    font-size: var(--font-size-lg);
    color: var(--text-light);
    margin-bottom: var(--spacing-2xl);
    line-height: 1.7;
}

.hero__buttons {
    display: flex;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
}

.hero__visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.hero__network {
    position: relative;
    width: 400px;
    height: 400px;
}

.network-node {
    position: absolute;
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: var(--font-size-xl);
    box-shadow: var(--shadow-lg);
    animation: pulse 2s infinite;
}

.network-node--center {
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 80px;
    height: 80px;
    font-size: var(--font-size-2xl);
    animation-delay: 0s;
}

.network-node--1 {
    top: 10%;
    left: 10%;
    animation-delay: 0.2s;
}

.network-node--2 {
    top: 10%;
    right: 10%;
    animation-delay: 0.4s;
}

.network-node--3 {
    bottom: 10%;
    left: 10%;
    animation-delay: 0.6s;
}

.network-node--4 {
    bottom: 10%;
    right: 10%;
    animation-delay: 0.8s;
}

.network-connections {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.connection-line {
    stroke: var(--primary-color);
    stroke-width: 2;
    opacity: 0.6;
    animation: flow 3s infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

@keyframes flow {
    0%, 100% { stroke-dasharray: 5, 5; stroke-dashoffset: 0; }
    50% { stroke-dashoffset: 10; }
}

/* ===== NAVIGATION CARDS ===== */
.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-xl);
}

.nav-card {
    background-color: var(--bg-card);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-2xl);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-light);
}

.nav-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.nav-card__icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-lg);
}

.nav-card__title {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-md);
    color: var(--text-color);
}

.nav-card__description {
    color: var(--text-light);
    margin-bottom: var(--spacing-lg);
    line-height: 1.6;
}

.nav-card__link {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--primary-color);
    font-weight: var(--font-weight-medium);
    text-decoration: none;
    transition: all var(--transition-normal);
}

.nav-card__link:hover {
    gap: var(--spacing-md);
}

/* ===== TOPOLOGY TABS ===== */
.topology-tabs {
    background-color: var(--bg-card);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

.tabs__nav {
    display: flex;
    background-color: var(--bg-light);
    border-bottom: 1px solid var(--border-color);
    overflow-x: auto;
}

.tab__btn {
    background: none;
    border: none;
    padding: var(--spacing-lg) var(--spacing-xl);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    color: var(--text-light);
    cursor: pointer;
    transition: all var(--transition-normal);
    white-space: nowrap;
    border-bottom: 3px solid transparent;
}

.tab__btn.active,
.tab__btn:hover {
    color: var(--primary-color);
    background-color: var(--bg-card);
}

.tab__btn.active {
    border-bottom-color: var(--primary-color);
}

.tabs__content {
    padding: var(--spacing-2xl);
}

.tab__panel {
    display: none;
}

.tab__panel.active {
    display: block;
}

.topology-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
    align-items: center;
}

.topology-visual {
    display: flex;
    justify-content: center;
}

.topology-diagram {
    width: 100%;
    max-width: 400px;
    height: 200px;
}

.bus-line {
    stroke: var(--primary-color);
    stroke-width: 4;
}

.node {
    fill: var(--secondary-color);
    stroke: var(--primary-color);
    stroke-width: 2;
}

.hub {
    fill: var(--accent-color);
    stroke: var(--primary-color);
    stroke-width: 3;
}

.connection {
    stroke: var(--primary-color);
    stroke-width: 2;
    opacity: 0.7;
}

.node-label,
.hub-label {
    fill: var(--text-color);
    font-size: 12px;
    text-anchor: middle;
    font-weight: var(--font-weight-medium);
}

.topology-info h3 {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-md);
    color: var(--text-color);
}

.topology-info p {
    color: var(--text-light);
    margin-bottom: var(--spacing-lg);
    line-height: 1.6;
}

.pros-cons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
}

.pros h4,
.cons h4 {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-medium);
    margin-bottom: var(--spacing-md);
}

.pros h4 {
    color: #10b981;
}

.cons h4 {
    color: #ef4444;
}

.pros ul,
.cons ul {
    list-style: none;
}

.pros li,
.cons li {
    padding: var(--spacing-xs) 0;
    color: var(--text-light);
    font-size: var(--font-size-sm);
}

/* ===== OS CARDS ===== */
.os-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-xl);
}

.os-card {
    background-color: var(--bg-card);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-2xl);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-light);
}

.os-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.os-card__header {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.os-card__icon {
    width: 60px;
    height: 60px;
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: var(--font-size-2xl);
}

.os-card__icon.windows {
    background: linear-gradient(135deg, #0078d4, #106ebe);
}

.os-card__icon.linux {
    background: linear-gradient(135deg, #fcc624, #f57c00);
}

.os-card__icon.macos {
    background: linear-gradient(135deg, #007aff, #5856d6);
}

.os-card__icon.mobile {
    background: linear-gradient(135deg, #34d399, #10b981);
}

.os-card__title {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    color: var(--text-color);
    margin-bottom: var(--spacing-xs);
}

.os-card__market {
    font-size: var(--font-size-sm);
    color: var(--text-light);
    background-color: var(--bg-light);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--border-radius);
}

.os-card__content p {
    color: var(--text-light);
    margin-bottom: var(--spacing-lg);
    line-height: 1.6;
}

.os-features {
    list-style: none;
}

.os-features li {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-xs) 0;
    color: var(--text-light);
    font-size: var(--font-size-sm);
}

.os-features i {
    color: #10b981;
    font-size: var(--font-size-xs);
}

/* ===== NOS SECTION ===== */
.nos-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
    align-items: start;
}

.nos-definition h3,
.nos-examples h3 {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-lg);
    color: var(--text-color);
}

.nos-definition p {
    color: var(--text-light);
    line-height: 1.7;
    margin-bottom: var(--spacing-xl);
}

.nos-features {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
}

.feature-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    background-color: var(--bg-card);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
}

.feature-item i {
    color: var(--primary-color);
    font-size: var(--font-size-xl);
}

.feature-item span {
    font-weight: var(--font-weight-medium);
    color: var(--text-color);
}

.nos-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.nos-item {
    display: flex;
    gap: var(--spacing-lg);
    padding: var(--spacing-lg);
    background-color: var(--bg-card);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
}

.nos-item:hover {
    box-shadow: var(--shadow-md);
    transform: translateX(5px);
}

.nos-item__icon {
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: var(--font-size-lg);
    flex-shrink: 0;
}

.nos-item__content h4 {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-sm);
    color: var(--text-color);
}

.nos-item__content p {
    color: var(--text-light);
    font-size: var(--font-size-sm);
    line-height: 1.5;
}

/* ===== SECURITY SECTION ===== */
.security-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-3xl);
}

.cia-triad h3,
.threats-section h3,
.protection-measures h3 {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-xl);
    text-align: center;
    color: var(--text-color);
}

.cia-diagram {
    display: flex;
    justify-content: center;
    margin-bottom: var(--spacing-xl);
}

.cia-triangle {
    position: relative;
    width: 300px;
    height: 260px;
}

.cia-point {
    position: absolute;
    width: 120px;
    height: 120px;
    border-radius: 50%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: var(--font-weight-semibold);
    text-align: center;
    box-shadow: var(--shadow-lg);
}

.cia-point i {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-sm);
}

.cia-point span {
    font-size: var(--font-size-sm);
}

.cia-confidentiality {
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    background: linear-gradient(135deg, #8b5cf6, #7c3aed);
}

.cia-integrity {
    bottom: 0;
    left: 0;
    background: linear-gradient(135deg, #10b981, #059669);
}

.cia-availability {
    bottom: 0;
    right: 0;
    background: linear-gradient(135deg, #f59e0b, #d97706);
}

.threats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.threat-card {
    background-color: var(--bg-card);
    padding: var(--spacing-xl);
    border-radius: var(--border-radius-lg);
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-light);
}

.threat-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.threat-card i {
    font-size: var(--font-size-3xl);
    color: #ef4444;
    margin-bottom: var(--spacing-lg);
}

.threat-card h4 {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-md);
    color: var(--text-color);
}

.threat-card p {
    color: var(--text-light);
    font-size: var(--font-size-sm);
    line-height: 1.5;
}

.measures-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.measure-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    padding: var(--spacing-xl);
    background-color: var(--bg-card);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-light);
}

.measure-item:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-lg);
}

.measure-item i {
    font-size: var(--font-size-2xl);
    color: #10b981;
    width: 50px;
    text-align: center;
}

.measure-item h4 {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-xs);
    color: var(--text-color);
}

.measure-item p {
    color: var(--text-light);
    font-size: var(--font-size-sm);
    line-height: 1.5;
}

/* ===== QUIZ SECTION ===== */
.quiz-container {
    max-width: 800px;
    margin: 0 auto;
    background-color: var(--bg-card);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

.quiz-progress {
    padding: var(--spacing-xl);
    background-color: var(--bg-light);
    border-bottom: 1px solid var(--border-color);
}

.progress-bar {
    width: 100%;
    height: 8px;
    background-color: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: var(--spacing-md);
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: 4px;
    transition: width var(--transition-normal);
    width: 10%;
}

.progress-text {
    font-size: var(--font-size-sm);
    color: var(--text-light);
    font-weight: var(--font-weight-medium);
}

.quiz-content {
    padding: var(--spacing-2xl);
}

.question-card {
    text-align: center;
}

.question-title {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-xl);
    color: var(--text-color);
    line-height: 1.4;
}

.answers-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.answer-btn {
    padding: var(--spacing-lg);
    background-color: var(--bg-light);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    color: var(--text-color);
    cursor: pointer;
    transition: all var(--transition-normal);
}

.answer-btn:hover {
    border-color: var(--primary-color);
    background-color: rgba(37, 99, 235, 0.1);
}

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

.answer-btn.correct {
    border-color: #10b981;
    background-color: #10b981;
    color: white;
}

.answer-btn.incorrect {
    border-color: #ef4444;
    background-color: #ef4444;
    color: white;
}

.quiz-actions {
    display: flex;
    justify-content: space-between;
    padding: var(--spacing-xl);
    background-color: var(--bg-light);
    border-top: 1px solid var(--border-color);
}

.quiz-results {
    max-width: 600px;
    margin: 0 auto;
}

.results-card {
    background-color: var(--bg-card);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-3xl);
    text-align: center;
    box-shadow: var(--shadow-lg);
}

.results-score {
    margin-bottom: var(--spacing-xl);
}

.score-circle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 120px;
    height: 120px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-lg);
}

.score-value {
    font-size: var(--font-size-3xl);
}

.score-total {
    font-size: var(--font-size-lg);
    opacity: 0.8;
}

.results-title {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-md);
    color: var(--text-color);
}

.results-message {
    color: var(--text-light);
    margin-bottom: var(--spacing-xl);
    line-height: 1.6;
}

/* ===== FOOTER ===== */
.footer {
    background-color: var(--bg-dark);
    color: var(--text-white);
    padding: var(--spacing-3xl) 0 var(--spacing-xl);
}

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

.footer__brand .nav__brand {
    color: var(--text-white);
    margin-bottom: var(--spacing-lg);
}

.footer__description {
    color: #94a3b8;
    line-height: 1.6;
    max-width: 300px;
}

.footer__links {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-xl);
}

.footer__title {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-lg);
    color: var(--text-white);
}

.footer__list {
    list-style: none;
}

.footer__list li {
    margin-bottom: var(--spacing-sm);
}

.footer__link {
    color: #94a3b8;
    text-decoration: none;
    transition: color var(--transition-normal);
}

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

.footer__bottom {
    padding-top: var(--spacing-xl);
    border-top: 1px solid #475569;
    text-align: center;
}

.footer__copy {
    color: #94a3b8;
    font-size: var(--font-size-sm);
}

/* ===== RESPONSIVE DESIGN ===== */
@media screen and (max-width: 1024px) {
    .hero__container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero__visual {
        order: -1;
    }
    
    .hero__network {
        width: 300px;
        height: 300px;
    }
    
    .topology-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }
    
    .nos-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }
    
    .footer__content {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }
}

@media screen and (max-width: 768px) {
    .nav__menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 100%;
        height: 100vh;
        background-color: var(--bg-color);
        flex-direction: column;
        justify-content: center;
        transition: right var(--transition-normal);
        z-index: 1001;
    }
    
    .nav__menu.show-menu {
        right: 0;
    }
    
    .nav__list {
        flex-direction: column;
        gap: var(--spacing-2xl);
        text-align: center;
    }
    
    .nav__link {
        font-size: var(--font-size-lg);
    }
    
    .nav__close,
    .nav__toggle {
        display: block;
    }
    
    .nav__close {
        position: absolute;
        top: var(--spacing-xl);
        right: var(--spacing-xl);
    }
    
    .hero__title {
        font-size: var(--font-size-3xl);
    }
    
    .hero__buttons {
        justify-content: center;
    }
    
    .section__title {
        font-size: var(--font-size-3xl);
    }
    
    .cards-grid {
        grid-template-columns: 1fr;
    }
    
    .tabs__nav {
        flex-wrap: wrap;
    }
    
    .tab__btn {
        flex: 1;
        min-width: 120px;
    }
    
    .os-grid {
        grid-template-columns: 1fr;
    }
    
    .pros-cons {
        grid-template-columns: 1fr;
    }
    
    .nos-features {
        grid-template-columns: 1fr;
    }
    
    .threats-grid {
        grid-template-columns: 1fr;
    }
    
    .measures-list {
        grid-template-columns: 1fr;
    }
    
    .answers-grid {
        grid-template-columns: 1fr;
    }
    
    .quiz-actions {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .cia-triangle {
        width: 250px;
        height: 220px;
    }
    
    .cia-point {
        width: 100px;
        height: 100px;
    }
    
    .cia-point i {
        font-size: var(--font-size-xl);
    }
}

@media screen and (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .section {
        padding: var(--spacing-2xl) 0;
    }
    
    .hero__title {
        font-size: var(--font-size-2xl);
    }
    
    .hero__buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    .nav-card,
    .os-card,
    .quiz-container,
    .results-card {
        padding: var(--spacing-lg);
    }
    
    .hero__network {
        width: 250px;
        height: 250px;
    }
    
    .network-node {
        width: 50px;
        height: 50px;
        font-size: var(--font-size-lg);
    }
    
    .network-node--center {
        width: 70px;
        height: 70px;
        font-size: var(--font-size-xl);
    }
}

/* ===== ANIMATIONS ===== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes fadeInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* AOS Animation Overrides */
[data-aos="fade-up"] {
    animation: fadeInUp 0.8s ease;
}

[data-aos="fade-left"] {
    animation: fadeInLeft 0.8s ease;
}

[data-aos="fade-right"] {
    animation: fadeInRight 0.8s ease;
}

/* ===== ACCESSIBILITY ===== */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    .network-node {
        animation: none;
    }
    
    .connection-line {
        animation: none;
    }
}

/* Focus styles for accessibility */
.btn:focus,
.nav__link:focus,
.tab__btn:focus,
.answer-btn:focus,
.theme-toggle:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --border-color: #000000;
        --text-light: #000000;
    }
    
    [data-theme="dark"] {
        --border-color: #ffffff;
        --text-light: #ffffff;
    }
}