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

:root {
    --primary-color: #1a365d;
    --secondary-color: #2c5282;
    --dark-bg: #0f1419;
    --light-bg: #f5f5f5;
    --card-bg: #ffffff;
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --border-color: #cbd5e0;
    --success-color: #2f855a;
    --warning-color: #c05621;
    --danger-color: #9b2c2c;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--light-bg);
}

/* Accessibility - Skip Link */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--primary-color);
    color: white;
    padding: 0.5rem 1rem;
    text-decoration: none;
    z-index: 100;
    border-radius: 0 0 4px 0;
}

.skip-link:focus {
    top: 0;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Breadcrumb Navigation */
.breadcrumb {
    margin-bottom: 1.5rem;
}

.breadcrumb ol {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.breadcrumb li {
    display: flex;
    align-items: center;
}

.breadcrumb li:not(:last-child)::after {
    content: "›";
    margin-left: 0.5rem;
    color: var(--text-secondary);
}

.breadcrumb a {
    color: var(--secondary-color);
    text-decoration: none;
    transition: color 0.2s;
}

.breadcrumb a:hover {
    color: var(--primary-color);
    text-decoration: underline;
}

/* Navbar */
.navbar {
    background: var(--primary-color);
    color: white;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    border-bottom: 1px solid #2c5282;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: bold;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-links a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover {
    color: #e2e8f0;
}

/* Hero Section */
.hero {
    background: var(--secondary-color);
    color: white;
    padding: 4rem 0;
    text-align: center;
    border-bottom: 2px solid var(--primary-color);
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    font-weight: 600;
}

.subtitle {
    font-size: 1.3rem;
    margin-bottom: 2rem;
    font-weight: 400;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    font-size: 1rem;
    line-height: 1.7;
}

.hero-content p {
    margin-bottom: 1rem;
}

.author-intro {
    background: rgba(255, 255, 255, 0.1);
    padding: 1.2rem;
    border-radius: 4px;
    border-left: 4px solid var(--secondary-color);
    font-style: italic;
    margin: 1.5rem 0;
}

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

.alt-bg {
    background-color: #ffffff;
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.section h2 {
    font-size: 2rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
    text-align: center;
    font-weight: 600;
}

.section-intro {
    text-align: center;
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
}

/* Encryption Cards */
.encryption-card {
    background: var(--card-bg);
    border-radius: 4px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.08);
    border: 1px solid var(--border-color);
}

.encryption-card:hover {
    box-shadow: 0 2px 4px rgba(0,0,0,0.12);
}

.encryption-card h3 {
    color: var(--primary-color);
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
    font-weight: 600;
}

.card-content {
    display: grid;
    gap: 2rem;
}

.info p {
    margin-bottom: 0.8rem;
    line-height: 1.8;
}

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

/* Demo Boxes */
.demo-box {
    background: #fafafa;
    padding: 1.5rem;
    border-radius: 4px;
    border: 1px solid var(--border-color);
}

.demo-box input,
.demo-box select,
.demo-box textarea {
    width: 100%;
    padding: 0.8rem;
    margin-bottom: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 3px;
    font-size: 0.95rem;
    transition: border-color 0.2s;
    background: white;
}

.demo-box input:focus,
.demo-box select:focus,
.demo-box textarea:focus {
    outline: none;
    border-color: var(--secondary-color);
}

.demo-box button {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.7rem 1.3rem;
    border-radius: 3px;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    margin-right: 0.5rem;
    margin-bottom: 0.5rem;
    transition: background 0.2s;
}

.demo-box button:hover {
    background: var(--secondary-color);
}

.demo-box button:active {
    background: #1a365d;
}

.output {
    background: white;
    padding: 0.8rem;
    border-radius: 3px;
    margin-top: 0.5rem;
    min-height: 40px;
    max-height: 120px;
    overflow-y: auto;
    word-wrap: break-word;
    font-family: 'Courier New', monospace;
    border: 1px solid var(--border-color);
    font-size: 0.9rem;
}

/* Comparison Tool */
.comparison-tool {
    background: var(--card-bg);
    border-radius: 4px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.08);
    border: 1px solid var(--border-color);
}

.comparison-tool h3 {
    color: var(--primary-color);
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    font-weight: 600;
}

.comparison-tool textarea {
    width: 100%;
    min-height: 100px;
    padding: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 3px;
    font-size: 0.95rem;
    margin-bottom: 1rem;
    font-family: inherit;
    background: white;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.9rem 1.8rem;
    border-radius: 3px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: background 0.2s;
}

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

.comparison-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.comparison-item {
    background: #fafafa;
    padding: 1.5rem;
    border-radius: 3px;
    border-left: 3px solid var(--primary-color);
    border: 1px solid var(--border-color);
    border-left: 3px solid var(--primary-color);
}

.comparison-item h4 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.comparison-item .result {
    font-family: 'Courier New', monospace;
    word-wrap: break-word;
    background: white;
    padding: 0.8rem;
    border-radius: 3px;
    margin-top: 0.5rem;
    font-size: 0.85rem;
    border: 1px solid var(--border-color);
}

/* Best Practices */
.best-practices {
    list-style: none;
    padding: 0;
}

.best-practices li {
    padding: 0.8rem 0.8rem 0.8rem 2.5rem;
    margin-bottom: 0.5rem;
    border-radius: 3px;
    font-size: 1rem;
    position: relative;
    border: 1px solid var(--border-color);
    background: white;
}

.best-practices li.recommended {
    border-left: 3px solid var(--success-color);
}

.best-practices li.recommended::before {
    content: "✓";
    position: absolute;
    left: 0.8rem;
    color: var(--success-color);
    font-weight: bold;
}

.best-practices li.not-recommended {
    border-left: 3px solid var(--danger-color);
}

.best-practices li.not-recommended::before {
    content: "✗";
    position: absolute;
    left: 0.8rem;
    color: var(--danger-color);
    font-weight: bold;
}

/* Footer */
footer {
    background: var(--dark-bg);
    color: white;
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    color: white;
}

.footer-section h4 {
    font-size: 1rem;
    margin-bottom: 0.8rem;
    color: var(--secondary-color);
}

.footer-section p {
    font-size: 0.9rem;
    line-height: 1.6;
    color: #cbd5e0;
    margin-bottom: 0.5rem;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: #cbd5e0;
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.2s;
}

.footer-section a:hover {
    color: white;
    text-decoration: underline;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 1.5rem;
    text-align: center;
    font-size: 0.85rem;
    color: #cbd5e0;
}

.footer-bottom p {
    margin-bottom: 0.5rem;
}

.footer-bottom a {
    color: #cbd5e0;
    text-decoration: none;
    margin: 0 0.5rem;
}

.footer-bottom a:hover {
    color: white;
    text-decoration: underline;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        flex-wrap: wrap;
        gap: 1rem;
        font-size: 0.9rem;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1.2rem;
    }

    .section h2 {
        font-size: 2rem;
    }

    .encryption-card {
        padding: 1.5rem;
    }

    .comparison-grid {
        grid-template-columns: 1fr;
    }

    .story-card {
        padding: 1.5rem;
    }

    .category-title {
        font-size: 1.5rem;
    }

    .best-practices-grid {
        grid-template-columns: 1fr;
    }

    .button-group {
        flex-direction: column;
    }

    .button-group button {
        width: 100%;
    }

    .mistakes-grid {
        grid-template-columns: 1fr;
    }

    .comparison-table {
        font-size: 0.85rem;
    }

    .comparison-table th,
    .comparison-table td {
        padding: 0.5rem;
    }

    /* Calculator Layout Mobile */
    .calculator-layout {
        grid-template-columns: 1fr;
    }

    .calculator-sidebar {
        position: static;
        margin-bottom: 2rem;
    }

    .calculator-nav {
        flex-direction: row;
        overflow-x: auto;
        gap: 0.3rem;
    }

    .calc-nav-link {
        white-space: nowrap;
        font-size: 0.85rem;
        padding: 0.6rem 0.8rem;
    }

    .sidebar-info {
        display: none;
    }

    .security-badge {
        position: static;
        display: inline-block;
        margin-bottom: 1rem;
    }
}

/* Learning Section Styles */
.narrator-intro {
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    font-style: italic;
    padding: 1.5rem;
    background: #f8f9fa;
    border-left: 4px solid var(--primary-color);
    border-radius: 3px;
}

.learning-category {
    margin-bottom: 4rem;
}

.category-title {
    font-size: 1.8rem;
    color: var(--primary-color);
    margin-bottom: 2rem;
    padding-bottom: 0.5rem;
    border-bottom: 3px solid var(--secondary-color);
    font-weight: 600;
}

.story-card {
    background: var(--card-bg);
    border-radius: 4px;
    padding: 2.5rem;
    margin-bottom: 2.5rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.08);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--secondary-color);
}

.story-card h4 {
    font-size: 1.6rem;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    font-weight: 600;
}

.story-content {
    line-height: 1.8;
}

.narrator-section {
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: #f8f9fa;
    border-radius: 3px;
}

.narrator-label {
    font-weight: 600;
    color: var(--secondary-color);
    font-size: 1rem;
    margin-bottom: 1rem;
    display: block;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border-bottom: 2px solid var(--secondary-color);
    padding-bottom: 0.3rem;
    display: inline-block;
}

.narrator-section p {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.technical-details {
    background: #ffffff;
    padding: 1.5rem;
    border-radius: 3px;
    border: 1px solid var(--border-color);
    margin-bottom: 2rem;
}

.section-label {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 1.1rem;
    margin-bottom: 1rem;
    display: block;
}

.technical-details p {
    margin-bottom: 0.8rem;
}

.technical-details ul {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}

.technical-details li {
    margin-bottom: 0.5rem;
}

/* Calculator Section Styles */
.calculator-layout {
    display: grid;
    grid-template-columns: 220px 1fr;
    gap: 1.5rem;
    margin-top: 1rem;
}

/* Calculator Sidebar */
.calculator-sidebar {
    background: var(--card-bg);
    border-radius: 4px;
    padding: 1rem;
    border: 1px solid var(--border-color);
    height: fit-content;
    position: sticky;
    top: 70px;
}

.calculator-sidebar h3 {
    font-size: 1rem;
    color: var(--primary-color);
    margin-bottom: 0.8rem;
    font-weight: 600;
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: 0.4rem;
}

.calculator-nav {
    display: flex;
    flex-direction: column;
    gap: 0.3rem;
    margin-bottom: 1rem;
}

.calc-nav-link {
    padding: 0.6rem 0.8rem;
    background: #f8f9fa;
    border-radius: 3px;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    font-size: 0.9rem;
    transition: all 0.2s;
    border-left: 3px solid transparent;
}

.calc-nav-link:hover {
    background: #e9ecef;
    border-left-color: var(--secondary-color);
}

.calc-nav-link.active {
    background: var(--primary-color);
    color: white;
    border-left-color: var(--secondary-color);
}

.sidebar-info {
    background: #f8f9fa;
    padding: 0.8rem;
    border-radius: 3px;
    border-left: 3px solid var(--secondary-color);
}

.sidebar-info h4 {
    font-size: 0.9rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.sidebar-info p {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-bottom: 0.3rem;
    line-height: 1.3;
}

.sidebar-info strong {
    color: var(--text-primary);
}

/* Calculator Main Area */
.calculator-main {
    min-height: 400px;
}

.calculator-section {
    display: none;
}

.calculator-section.active {
    display: block;
}

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

.section-header h3 {
    font-size: 1.4rem;
    color: var(--primary-color);
    margin-bottom: 0.3rem;
    font-weight: 600;
}

.section-description {
    color: var(--text-secondary);
    font-size: 0.85rem;
    line-height: 1.4;
}

.calculator-category {
    margin-bottom: 3rem;
}

.calculator-card {
    background: var(--card-bg);
    border-radius: 4px;
    padding: 1.2rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.08);
    border: 1px solid var(--border-color);
    position: relative;
}

.calculator-card.featured {
    border: 2px solid var(--primary-color);
    box-shadow: 0 2px 8px rgba(37, 99, 235, 0.1);
}

.calculator-card h4 {
    font-size: 1.1rem;
    color: var(--primary-color);
    margin-bottom: 0.8rem;
    font-weight: 600;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.4rem;
}

/* Security Badges */
.security-badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    padding: 0.4rem 0.8rem;
    border-radius: 3px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.security-badge:not(.insecure) {
    background: #d1fae5;
    color: var(--success-color);
    border: 1px solid var(--success-color);
}

.security-badge.insecure {
    background: #fee2e2;
    color: var(--danger-color);
    border: 1px solid var(--danger-color);
}

.calculator-content input,
.calculator-content select,
.calculator-content textarea {
    width: 100%;
    padding: 0.6rem;
    border: 1px solid var(--border-color);
    border-radius: 3px;
    font-size: 0.9rem;
    background: white;
}

.calculator-content input:focus,
.calculator-content select:focus,
.calculator-content textarea:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 0 3px rgba(44, 82, 130, 0.1);
}

.calculator-content textarea {
    resize: vertical;
    min-height: 60px;
    max-height: 100px;
    font-family: 'Courier New', monospace;
}

.calculator-content select {
    cursor: pointer;
}

/* Form Grid Layout */
.form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1rem;
}

.form-grid .form-row {
    margin-bottom: 0;
}

.form-row.full-width {
    grid-column: 1 / -1;
}

/* Form Row Styling */
.form-row {
    margin-bottom: 0.8rem;
}

.form-row label {
    display: block;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.3rem;
    font-size: 0.9rem;
}

.form-hint {
    display: block;
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 0.2rem;
    font-style: italic;
}

.button-group {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.button-group button {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.6rem 1rem;
    border-radius: 3px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: background 0.2s;
}

.button-group button:hover {
    background: var(--secondary-color);
}

.button-group .btn-secondary {
    background: #6c757d;
}

.button-group .btn-secondary:hover {
    background: #5a6268;
}

.calculator-note {
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-style: italic;
    margin-top: 0.5rem;
    line-height: 1.4;
}

.calculator-note strong {
    color: var(--text-primary);
}

/* Best Practices Grid */
.best-practices-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.practices-column h5 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
    font-weight: 600;
}

/* Confusion Highlight */
.confusion-highlight {
    border-left: 4px solid var(--warning-color);
    background: #fffbeb;
}

/* Example Boxes */
.example-box {
    background: #f0f9ff;
    border-left: 3px solid var(--primary-color);
    padding: 1.5rem;
    margin: 1.5rem 0;
    border-radius: 3px;
}

.example-box p {
    margin-bottom: 0.5rem;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
}

.warning-box {
    background: #fff5f5;
    border-left: 3px solid var(--danger-color);
}

/* Comparison Table */
.comparison-table {
    overflow-x: auto;
    margin: 2rem 0;
}

.comparison-table table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    border: 1px solid var(--border-color);
}

.comparison-table th {
    background: var(--primary-color);
    color: white;
    padding: 1rem;
    text-align: left;
    font-weight: 600;
    border: 1px solid var(--border-color);
}

.comparison-table td {
    padding: 1rem;
    border: 1px solid var(--border-color);
}

.comparison-table tbody tr:nth-child(even) {
    background: #f8f9fa;
}

.comparison-table tbody tr:hover {
    background: #e9ecef;
}

/* Mistakes Grid */
.mistakes-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.mistake-item {
    padding: 1.5rem;
    border-radius: 4px;
    border: 2px solid;
}

.mistake-item.wrong {
    background: #fff5f5;
    border-color: var(--danger-color);
}

.mistake-item.right {
    background: #f0fdf4;
    border-color: var(--success-color);
}

.mistake-item h5 {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    font-weight: 600;
}

.mistake-item.wrong h5 {
    color: var(--danger-color);
}

.mistake-item.right h5 {
    color: var(--success-color);
}

.mistake-item p {
    margin-bottom: 0.5rem;
}

.mistake-item .explanation {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-style: italic;
    margin-top: 0.5rem;
}

.comparison-card {
    border-left: 4px solid var(--secondary-color);
}

/* Animations - Removed for professional appearance */

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

::-webkit-scrollbar-track {
    background: var(--light-bg);
}

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

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-color);
}