:root {
    --primary: #2563EB;
    --primary-dark: #1D4ED8;
    --primary-light: #DBEAFE;
    --primary-50: #EFF6FF;
    --accent: #F59E0B;
    --accent-light: #FEF3C7;
    --success: #10B981;
    --success-light: #D1FAE5;
    --gray-900: #111827;
    --gray-800: #1F2937;
    --gray-700: #374151;
    --gray-600: #4B5563;
    --gray-500: #6B7280;
    --gray-400: #9CA3AF;
    --gray-300: #D1D5DB;
    --gray-200: #E5E7EB;
    --gray-100: #F3F4F6;
    --gray-50: #F9FAFB;
    --white: #FFFFFF;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
    --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);
    --radius: 12px;
    --radius-sm: 8px;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    font-family: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--gray-50);
    color: var(--gray-700);
    line-height: 1.7;
    font-size: 17px;
}
header {
    background: var(--white);
    border-bottom: 1px solid var(--gray-200);
    position: sticky;
    top: 0;
    z-index: 1000;
    overflow: visible;
}
.header-main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0.875rem 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 2rem;
    position: relative;
}
.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-shrink: 0;
}
.logo-icon {
    width: 32px;
    height: 32px;
    flex-shrink: 0;
}
.nav-desktop {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}
.nav-item {
    position: relative;
    z-index: 1001;
}
.nav-link {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.625rem 1rem;
    color: var(--gray-700);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.9375rem;
    border-radius: var(--radius-sm);
    transition: all 0.2s ease;
}
.nav-link:hover {
    background: var(--gray-100);
    color: var(--primary);
}
.nav-link svg {
    width: 16px;
    height: 16px;
    transition: transform 0.2s ease;
}
.nav-item:hover .nav-link svg {
    transform: rotate(180deg);
}
.mega-menu {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    padding: 1.5rem;
    min-width: 580px;
    opacity: 0;
    visibility: hidden;
    transition: all 0.2s ease;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
    z-index: 1002;
}
.nav-item:hover .mega-menu {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}
.mega-menu-section h4 {
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--gray-400);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.75rem;
}
.mega-menu-section a {
    display: block;
    padding: 0.375rem 0;
    color: var(--gray-600);
    text-decoration: none;
    font-size: 0.875rem;
    transition: color 0.15s ease;
}
.mega-menu-section a:hover {
    color: var(--primary);
}
.nav-mobile-toggle {
    display: none;
    background: none;
    border: none;
    padding: 0.5rem;
    cursor: pointer;
    color: var(--gray-700);
}
.nav-mobile-toggle svg {
    width: 24px;
    height: 24px;
}
.breadcrumbs {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 1.5rem;
    position: relative;
    z-index: 1;
}
.breadcrumbs-list {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    list-style: none;
    font-size: 0.875rem;
    flex-wrap: wrap;
}
.breadcrumbs-list li {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.breadcrumbs-list a {
    color: var(--gray-500);
    text-decoration: none;
    transition: color 0.15s ease;
}
.breadcrumbs-list a:hover {
    color: var(--primary);
}
.breadcrumbs-list .separator {
    color: var(--gray-400);
}
.breadcrumbs-list .current {
    color: var(--gray-700);
    font-weight: 500;
}
.main-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem 4rem;
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 3rem;
    align-items: start;
    position: relative;
    z-index: 1;
}
.article {
    background: var(--white);
    border-radius: var(--radius);
    border: 1px solid var(--gray-200);
    overflow: hidden;
}
.article-header {
    padding: 2.5rem 2.5rem 2rem;
    border-bottom: 1px solid var(--gray-100);
}
.article-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}
.article-tag {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.375rem 0.875rem;
    background: var(--primary-light);
    color: var(--primary-dark);
    font-size: 0.8125rem;
    font-weight: 600;
    border-radius: 100px;
}
.article-grade {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.375rem 0.875rem;
    background: var(--accent-light);
    color: var(--gray-700);
    font-size: 0.8125rem;
    font-weight: 600;
    border-radius: 100px;
}
.article-title {
    font-size: 2.25rem;
    font-weight: 800;
    color: var(--gray-900);
    line-height: 1.2;
    margin-bottom: 1rem;
}
.article-intro {
    font-size: 1.125rem;
    color: var(--gray-600);
    line-height: 1.7;
}
.article-body {
    padding: 2.5rem;
}
.article-body h2 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--gray-900);
    margin: 2.5rem 0 1rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--gray-100);
    scroll-margin-top: 100px;
}
.article-body h2:first-child {
    margin-top: 0;
    padding-top: 0;
    border-top: none;
}
.article-body h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-800);
    margin: 2rem 0 0.75rem;
    scroll-margin-top: 100px;
}
.article-body p {
    margin-bottom: 1.25rem;
}
.article-body ul, .article-body ol {
    margin: 1rem 0 1.5rem 1.5rem;
}
.article-body li {
    margin-bottom: 0.5rem;
}
.formula-box {
    background: linear-gradient(135deg, var(--primary-50) 0%, var(--primary-light) 100%);
    border: 2px solid var(--primary);
    border-radius: var(--radius);
    padding: 2rem;
    margin: 2rem 0;
    text-align: center;
}
.formula-box.accent {
    background: linear-gradient(135deg, var(--accent-light) 0%, #FDE68A 100%);
    border-color: var(--accent);
}
.formula-box.success {
    background: linear-gradient(135deg, var(--success-light) 0%, #A7F3D0 100%);
    border-color: var(--success);
}
.formula-label {
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--primary-dark);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 1rem;
}
.formula-box.accent .formula-label {
    color: var(--gray-700);
}
.formula-box.success .formula-label {
    color: #065F46;
}
.formula-content {
    font-size: 1.75rem;
    color: var(--gray-900);
    font-weight: 600;
}
.formula-note {
    font-size: 0.875rem;
    color: var(--gray-600);
    margin-top: 1rem;
}
.example-box {
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.5rem 2rem;
    margin: 1.5rem 0;
}
.example-box-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    color: var(--gray-800);
    margin-bottom: 1rem;
}
.example-box-header svg {
    width: 20px;
    height: 20px;
    color: var(--primary);
}
.example-step {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
    align-items: flex-start;
}
.example-step:last-child {
    margin-bottom: 0;
}
.step-number {
    width: 28px;
    height: 28px;
    background: var(--primary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.875rem;
    font-weight: 700;
    flex-shrink: 0;
}
.step-content {
    flex: 1;
    padding-top: 0.125rem;
}
.info-box {
    background: var(--primary-50);
    border-left: 4px solid var(--primary);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    padding: 1.25rem 1.5rem;
    margin: 1.5rem 0;
}
.info-box p {
    margin: 0;
    color: var(--gray-700);
}
.info-box strong {
    color: var(--gray-900);
}
.tip-box {
    background: var(--success-light);
    border-left: 4px solid var(--success);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    padding: 1.25rem 1.5rem;
    margin: 1.5rem 0;
}
.tip-box p {
    margin: 0;
    color: var(--gray-700);
}
.warning-box {
    background: #FEF2F2;
    border-left: 4px solid #EF4444;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    padding: 1.25rem 1.5rem;
    margin: 1.5rem 0;
}
.warning-box p {
    margin: 0;
    color: var(--gray-700);
}
.comparison-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    font-size: 0.9375rem;
}
.comparison-table th,
.comparison-table td {
    padding: 1rem 1.25rem;
    text-align: left;
    border: 1px solid var(--gray-200);
}
.comparison-table th {
    background: var(--gray-100);
    font-weight: 600;
    color: var(--gray-800);
}
.comparison-table td {
    background: var(--white);
}
.comparison-table tr:hover td {
    background: var(--gray-50);
}
.sidebar {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    position: sticky;
    top: 100px;
}
.sidebar-card {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.5rem;
}
.sidebar-card h3 {
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--gray-400);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 1rem;
}
.sidebar-toc a {
    display: block;
    padding: 0.5rem 0;
    color: var(--gray-600);
    text-decoration: none;
    font-size: 0.9375rem;
    border-left: 2px solid transparent;
    padding-left: 0.75rem;
    margin-left: -0.75rem;
    transition: all 0.15s ease;
}
.sidebar-toc a:hover,
.sidebar-toc a.active {
    color: var(--primary);
    border-left-color: var(--primary);
}
.sidebar-related a {
    display: flex;
    align-items: center;
    gap: 0.625rem;
    padding: 0.625rem 0;
    color: var(--gray-700);
    text-decoration: none;
    font-size: 0.9375rem;
    transition: color 0.15s ease;
}
.sidebar-related a:hover {
    color: var(--primary);
}
.sidebar-related a::before {
    content: '';
    width: 6px;
    height: 6px;
    background: var(--gray-300);
    border-radius: 50%;
    flex-shrink: 0;
}
.sidebar-related a:hover::before {
    background: var(--primary);
}
.sidebar-cta {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: white;
    text-align: center;
}
.sidebar-cta h3 {
    color: rgba(255,255,255,0.8);
}
.sidebar-cta p {
    font-size: 0.9375rem;
    margin-bottom: 1rem;
    opacity: 0.9;
}
.sidebar-cta-btn {
    display: inline-block;
    background: white;
    color: var(--primary);
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-sm);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9375rem;
    transition: transform 0.15s ease;
}
.sidebar-cta-btn:hover {
    transform: translateY(-2px);
}
.exercise-container {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    margin-top: 1.5rem;
}
.exercise {
    background: var(--white);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.5rem;
    transition: border-color 0.2s ease;
}
.exercise.correct {
    border-color: var(--success);
    background: linear-gradient(135deg, var(--success-light) 0%, var(--white) 100%);
}
.exercise.incorrect {
    border-color: #EF4444;
    background: linear-gradient(135deg, #FEF2F2 0%, var(--white) 100%);
}
.exercise-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}
.exercise-number {
    font-weight: 700;
    color: var(--gray-800);
    font-size: 1rem;
}
.exercise-difficulty {
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.25rem 0.625rem;
    border-radius: 100px;
    text-transform: uppercase;
    letter-spacing: 0.025em;
}
.exercise-difficulty.easy {
    background: var(--success-light);
    color: #065F46;
}
.exercise-difficulty.medium {
    background: var(--accent-light);
    color: #92400E;
}
.exercise-difficulty.hard {
    background: #FEE2E2;
    color: #991B1B;
}
.exercise-question {
    margin-bottom: 1.25rem;
}
.exercise-question p {
    margin-bottom: 0.5rem;
}
.exercise-formula {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-900);
}
.exercise-options {
    display: flex;
    flex-direction: column;
    gap: 0.625rem;
    margin-bottom: 1rem;
}
.exercise-option {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.875rem 1rem;
    background: var(--gray-50);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.15s ease;
}
.exercise-option:hover {
    border-color: var(--primary);
    background: var(--primary-50);
}
.exercise-option input[type="radio"] {
    width: 18px;
    height: 18px;
    accent-color: var(--primary);
    cursor: pointer;
}
.exercise-option span {
    flex: 1;
    font-size: 1rem;
    color: var(--gray-700);
}
.exercise-option.correct-answer {
    border-color: var(--success);
    background: var(--success-light);
}
.exercise-option.wrong-answer {
    border-color: #EF4444;
    background: #FEF2F2;
}
.exercise-input-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
}
.exercise-input {
    padding: 0.875rem 1rem;
    font-size: 1.125rem;
    font-family: inherit;
    border: 2px solid var(--gray-300);
    border-radius: var(--radius-sm);
    width: 150px;
    text-align: center;
    transition: border-color 0.15s ease;
}
.exercise-input:focus {
    outline: none;
    border-color: var(--primary);
}
.exercise-input.correct {
    border-color: var(--success);
    background: var(--success-light);
}
.exercise-input.incorrect {
    border-color: #EF4444;
    background: #FEF2F2;
}
.exercise-feedback {
    padding: 0.875rem 1rem;
    border-radius: var(--radius-sm);
    margin-bottom: 1rem;
    display: none;
    font-weight: 500;
}
.exercise-feedback.show {
    display: block;
}
.exercise-feedback.correct {
    background: var(--success-light);
    color: #065F46;
    border-left: 4px solid var(--success);
}
.exercise-feedback.incorrect {
    background: #FEF2F2;
    color: #991B1B;
    border-left: 4px solid #EF4444;
}
.exercise-check {
    background: var(--primary);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    font-size: 0.9375rem;
    font-weight: 600;
    font-family: inherit;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: background 0.15s ease;
}
.exercise-check:hover {
    background: var(--primary-dark);
}
.exercise-check:disabled {
    background: var(--gray-400);
    cursor: not-allowed;
}
.exercise-result {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    border-radius: var(--radius);
    padding: 2rem;
    text-align: center;
    color: white;
    margin-top: 2rem;
    display: none;
}
.exercise-result.show {
    display: block;
}
.exercise-result-header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
}
.exercise-result-icon {
    font-size: 1.5rem;
}
.exercise-result-title {
    font-size: 1.25rem;
    font-weight: 700;
}
.exercise-result-score {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}
.exercise-result-message {
    font-size: 1rem;
    opacity: 0.9;
    margin-bottom: 1.5rem;
}
.exercise-reset {
    background: white;
    color: var(--primary);
    border: none;
    padding: 0.75rem 1.5rem;
    font-size: 0.9375rem;
    font-weight: 600;
    font-family: inherit;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: transform 0.15s ease;
}
.exercise-reset:hover {
    transform: translateY(-2px);
}
footer {
    background: var(--gray-900);
    color: var(--gray-400);
    padding: 4rem 2rem 2rem;
    margin-top: auto;
}
.footer-content {
    max-width: 1200px;
    margin: 0 auto;
}
.footer-grid {
    display: grid;
    grid-template-columns: 2fr repeat(3, 1fr);
    gap: 3rem;
    margin-bottom: 3rem;
}
.footer-brand {
    max-width: 280px;
}
.footer-logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--white);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.footer-brand p {
    font-size: 0.9375rem;
    line-height: 1.6;
}
.footer-col h4 {
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--white);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 1.25rem;
}
.footer-col a {
    display: block;
    color: var(--gray-400);
    text-decoration: none;
    font-size: 0.9375rem;
    padding: 0.375rem 0;
    transition: color 0.15s ease;
}
.footer-col a:hover {
    color: var(--white);
}
.footer-bottom {
    border-top: 1px solid var(--gray-800);
    padding-top: 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
    font-size: 0.875rem;
}
.footer-links {
    display: flex;
    gap: 2rem;
}
.footer-links a {
    color: var(--gray-400);
    text-decoration: none;
    transition: color 0.15s ease;
}
.footer-links a:hover {
    color: var(--white);
}
@media (max-width: 1024px) {
    .main-container {
        grid-template-columns: 1fr;
    }
    .sidebar {
        position: static;
        display: grid;
        grid-template-columns: repeat(2, 1fr);
    }
    .sidebar-cta {
        grid-column: span 2;
    }
}
@media (max-width: 768px) {
    .nav-desktop {
        display: none;
    }
    .nav-mobile-toggle {
        display: block;
    }
    .article-header {
        padding: 1.5rem;
    }
    .article-title {
        font-size: 1.75rem;
    }
    .article-body {
        padding: 1.5rem;
    }
    .formula-content {
        font-size: 1.25rem;
    }
    .sidebar {
        grid-template-columns: 1fr;
    }
    .sidebar-cta {
        grid-column: span 1;
    }
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
}
.katex {
    font-size: 1.1em;
}
.formula-content .katex {
    font-size: 1.3em;
}

/* ==================== STARTSEITE STYLES ==================== */


/* Hero Section (Startseite) */
.hero {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    padding: 4rem 2rem;
    text-align: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    color: var(--white);
}

.hero h1 {
    font-size: 2.75rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.25rem;
    opacity: 0.95;
    margin-bottom: 2rem;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 3rem;
    flex-wrap: wrap;
}

.hero-stat {
    text-align: center;
}

.hero-stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    display: block;
}

.hero-stat-label {
    font-size: 0.9rem;
    opacity: 0.9;
}

/* Quick Nav (Startseite) */
.quick-nav {
    background: var(--white);
    border-bottom: 1px solid var(--gray-200);
    padding: 1rem 2rem;
}

.quick-nav-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    justify-content: center;
}

.quick-nav a {
    padding: 0.5rem 1rem;
    background: var(--gray-100);
    border-radius: 20px;
    text-decoration: none;
    color: var(--gray-700);
    font-size: 0.875rem;
    font-weight: 500;
    transition: all 0.2s ease;
}

.quick-nav a:hover {
    background: var(--primary);
    color: white;
}

/* Category Section (Startseite) */
.category-section {
    margin-bottom: 3rem;
}

.category-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--primary-light);
}

.category-icon {
    width: 48px;
    height: 48px;
    background: var(--primary-light);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.category-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--gray-900);
}

.category-count {
    font-size: 0.875rem;
    color: var(--gray-500);
    margin-left: auto;
}

.subcategory {
    margin-bottom: 1.5rem;
}

.subcategory-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--gray-700);
    margin-bottom: 0.75rem;
}

.topics-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.topic-link {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: 8px;
    text-decoration: none;
    color: var(--gray-700);
    font-size: 0.875rem;
    transition: all 0.2s ease;
}

.topic-link:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--primary-50);
}

/* Info Section (Startseite) */
.info-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-top: 4rem;
}

.info-card {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.5rem;
}

.info-card h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 0.75rem;
}

.info-card p {
    color: var(--gray-600);
    font-size: 0.9375rem;
    margin-bottom: 1rem;
}

.info-card ul {
    list-style: none;
}

.info-card li {
    padding: 0.25rem 0;
    padding-left: 1.5rem;
    position: relative;
    font-size: 0.9375rem;
    color: var(--gray-600);
}

.info-card li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary);
    font-weight: 600;
}

.audience-banner {
    background: var(--primary-light);
    border-radius: var(--radius);
    padding: 2rem;
    text-align: center;
    margin-top: 3rem;
}

.audience-banner h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 0.5rem;
}

.audience-banner p {
    color: var(--gray-700);
    max-width: 600px;
    margin: 0 auto;
}

/* Responsive Startseite */
@media (max-width: 768px) {
    .hero {
padding: 3rem 1.5rem;
    }
    .hero h1 {
font-size: 2rem;
    }
    .hero-subtitle {
font-size: 1.0625rem;
    }
}

/* ==================== KATEGORIE-ÜBERSICHTSSEITEN ==================== */

.category-overview {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem 3rem;
}

.category-hero {
    text-align: center;
    padding: 3rem 1.5rem;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: white;
    margin: 0 -1.5rem 2rem;
}

.category-hero-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.category-hero h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
}

.category-hero p {
    font-size: 1.125rem;
    opacity: 0.95;
    max-width: 600px;
    margin: 0 auto;
}

.category-content {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.subcategory-section {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.5rem;
}

.subcategory-section h2 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--primary-light);
}

.topic-card {
    display: inline-block;
    padding: 0.625rem 1rem;
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: 8px;
    text-decoration: none;
    color: var(--gray-700);
    font-size: 0.9375rem;
    transition: all 0.2s ease;
}

.topic-card:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--primary-light);
}

/* Topic Overview Section für Kategorieseiten */
.topic-overview {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--gray-200);
}

.topic-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1rem;
    margin-top: 1.5rem;
}

.topic-card-link {
    text-decoration: none;
}

.topic-card-mini {
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.25rem;
    transition: all 0.2s ease;
}

.topic-card-mini:hover {
    border-color: var(--primary);
    background: var(--primary-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.topic-card-mini h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 0.375rem;
}

.topic-card-link:hover .topic-card-mini h3 {
    color: var(--primary);
}

.topic-card-mini p {
    font-size: 0.875rem;
    color: var(--gray-500);
    margin: 0;
    line-height: 1.5;
}

@media (max-width: 768px) {
    .category-hero {
padding: 2rem 1rem;
    }
    
    .category-hero h1 {
font-size: 1.75rem;
    }
    
    .category-hero p {
font-size: 1rem;
    }
    
    .subcategory-section {
padding: 1rem;
    }
}

/* ==================== RECHTLICHE SEITEN (Impressum, Datenschutz) ==================== */

.legal-page {
    max-width: 800px;
    margin: 0 auto;
    padding: 3rem 1.5rem;
}

.legal-container h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: 2rem;
}

.legal-notice {
    background: var(--primary-light);
    border: 1px solid var(--primary);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 2rem;
}

.legal-notice p {
    color: var(--gray-900);
    margin: 0;
}

.legal-section {
    background: var(--white);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 1.5rem 2rem;
    margin-bottom: 1.5rem;
}

.legal-section h2 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 1rem;
}

.legal-section address {
    font-style: normal;
    margin-bottom: 1rem;
}

.legal-section a {
    color: var(--primary);
    text-decoration: none;
}

.legal-section a:hover {
    text-decoration: underline;
}

.legal-details {
    display: grid;
    gap: 0.75rem;
}

.legal-details dt {
    font-weight: 600;
    color: var(--gray-700);
}

.legal-details dd {
    margin: 0 0 0.5rem 0;
    color: var(--gray-600);
}

.legal-disclaimer {
    background: var(--accent-light);
    border: 1px solid var(--accent);
    border-radius: var(--radius);
    padding: 1.5rem 2rem;
}

.legal-disclaimer h2 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 0.75rem;
}

.legal-disclaimer p {
    color: var(--gray-700);
    margin: 0;
}

@media (max-width: 768px) {
    .legal-page {
padding: 2rem 1.5rem;
    }
    
    .legal-container h1 {
font-size: 1.5rem;
    }
    
    .legal-section {
padding: 1.5rem;
    }
}

/* ==================== SECTION LABELS (ersetzt h4) ==================== */

.mega-menu-title {
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--gray-400);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.75rem;
}

.section-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--gray-500);
    text-transform: uppercase;
    letter-spacing: 0.03em;
    margin-bottom: 0.5rem;
}

.footer-col .section-label {
    color: var(--gray-300);
    margin-bottom: 0.75rem;
}

/* Navigation Links ohne Dropdown */
.nav-link-simple {
    padding: 0.625rem 1rem !important;
}

.nav-link-simple svg {
    display: none;
}

/* Mega-Menu Titel als Links */
a.mega-menu-title {
    display: block;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--gray-500);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.75rem;
    text-decoration: none;
    transition: color 0.15s ease;
}

a.mega-menu-title:hover {
    color: var(--primary);
}

/* ==================== STARTSEITE LAYOUT ==================== */

.homepage-main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 3rem 1.5rem;
}

@media (max-width: 768px) {
    .homepage-main {
        padding: 2rem 1rem;
    }
}

/* ==================== ÜBUNGEN FEEDBACK ==================== */

.exercise-feedback {
    display: none;
    margin-top: 1rem;
    padding: 0.75rem 1rem;
    border-radius: var(--radius-sm);
}

.feedback-success {
    color: #065f46;
    background: #d1fae5;
    display: block;
    padding: 0.75rem 1rem;
    border-radius: var(--radius-sm);
    font-weight: 500;
}

.feedback-error {
    color: #991b1b;
    background: #fee2e2;
    display: block;
    padding: 0.75rem 1rem;
    border-radius: var(--radius-sm);
    font-weight: 500;
}

.exercise-option.correct {
    background: #d1fae5 !important;
    border-color: #10b981 !important;
}

.exercise-option.correct span {
    color: #065f46;
}

.exercise-option.incorrect {
    background: #fee2e2 !important;
    border-color: #ef4444 !important;
}

.exercise-option.incorrect span {
    color: #991b1b;
}

.exercise-option input:disabled + span {
    cursor: default;
}

/* ==================== MOBILE NAVIGATION ==================== */

.nav-mobile {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--white);
    z-index: 1000;
    flex-direction: column;
}

.nav-mobile.active {
    display: flex;
}

.nav-mobile-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--gray-200);
}

.nav-mobile-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--gray-600);
    padding: 0.5rem;
}

.nav-mobile-content {
    flex: 1;
    overflow-y: auto;
    padding: 1rem;
}

.nav-mobile-content a {
    display: block;
    padding: 1rem 1.5rem;
    color: var(--gray-700);
    text-decoration: none;
    font-size: 1.125rem;
    font-weight: 500;
    border-radius: var(--radius-sm);
    transition: background 0.15s ease;
}

.nav-mobile-content a:hover {
    background: var(--gray-100);
}

.nav-mobile-toggle {
    display: none;
    background: none;
    border: none;
    padding: 0.5rem;
    cursor: pointer;
}

.nav-mobile-toggle svg {
    width: 24px;
    height: 24px;
    color: var(--gray-700);
}

@media (max-width: 1024px) {
    .nav-desktop {
        display: none;
    }
    
    .nav-mobile-toggle {
        display: block;
    }
}

/* Highlight Box */
.highlight-box {
    background: var(--primary-light);
    border-left: 4px solid var(--primary);
    padding: 1rem 1.25rem;
    margin: 1.5rem 0;
    border-radius: 0 8px 8px 0;
}

.highlight-box p {
    margin: 0.5rem 0;
}

.highlight-box p:first-child {
    margin-top: 0;
}

.highlight-box p:last-child {
    margin-bottom: 0;
}

/* Table of Contents */
.toc {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.toc a {
    color: var(--gray-600);
    text-decoration: none;
    font-size: 0.9rem;
    padding: 0.25rem 0;
    transition: color 0.2s;
}

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

/* Info Table */
.info-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0;
}

.info-table th,
.info-table td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--gray-200);
}

.info-table th {
    background: var(--gray-50);
    font-weight: 600;
}

/* Print Styles */
@media print {
    .header,
    .main-nav,
    .mobile-menu-btn,
    .sidebar,
    .related-topics,
    .toc-container,
    .exercise-options,
    .check-answer-btn,
    .exercise-feedback,
    footer {
        display: none !important;
    }
    
    body {
        font-size: 12pt;
        line-height: 1.5;
        color: #000;
        background: #fff;
    }
    
    .article {
        max-width: 100%;
        margin: 0;
        padding: 0;
    }
    
    .article-title {
        font-size: 18pt;
        color: #000;
    }
    
    h2 {
        font-size: 14pt;
        page-break-after: avoid;
    }
    
    .formula-box,
    .highlight-box,
    .example-box {
        border: 1px solid #000;
        background: #f5f5f5;
        page-break-inside: avoid;
    }
    
    a {
        color: #000;
        text-decoration: underline;
    }
    
    a[href^="http"]:after {
        content: " (" attr(href) ")";
        font-size: 9pt;
    }
    
    .breadcrumbs {
        font-size: 10pt;
        margin-bottom: 1em;
    }
}

/* Dropdown Navigation */
.nav-item.dropdown {
    position: relative;
}

.dropdown-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    background: #fff;
    min-width: 220px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
    border-radius: 8px;
    padding: 0.5rem 0;
    z-index: 1000;
    list-style: none;
    margin: 0;
}

.nav-item.dropdown:hover .dropdown-menu {
    display: block;
}

.dropdown-menu li {
    margin: 0;
}

.dropdown-menu a {
    display: block;
    padding: 0.6rem 1.2rem;
    color: #374151;
    text-decoration: none;
    font-size: 0.9rem;
    transition: background 0.2s, color 0.2s;
}

.dropdown-menu a:hover {
    background: #f3f4f6;
    color: #6366f1;
}

/* Dropdown-Pfeil */
.nav-item.dropdown > .nav-link::after {
    content: ' ▾';
    font-size: 0.7em;
    opacity: 0.7;
}

/* Mobile: Dropdown immer sichtbar wenn Menü offen */
@media (max-width: 768px) {
    .dropdown-menu {
        position: static;
        box-shadow: none;
        background: #f9fafb;
        border-radius: 0;
        padding: 0;
        display: none;
    }
    
    .nav-item.dropdown.active .dropdown-menu {
        display: block;
    }
    
    .dropdown-menu a {
        padding-left: 2rem;
    }
}

/* Navigation Styles - Korrektur */
.main-nav {
    display: flex;
    align-items: center;
}

.nav-list {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: 0.5rem;
}

.nav-list > li {
    position: relative;
}

.nav-link {
    display: block;
    padding: 0.5rem 1rem;
    color: #374151;
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    border-radius: 6px;
    transition: background 0.2s, color 0.2s;
}

.nav-link:hover {
    background: #f3f4f6;
    color: #6366f1;
}

/* Header Container */
.header {
    background: #fff;
    border-bottom: 1px solid #e5e7eb;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0.75rem 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 2rem;
}

/* Logo */
.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    font-weight: 700;
    font-size: 1.25rem;
    color: #111827;
}

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

/* Mobile Menu Button */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 4px;
    padding: 8px;
    background: none;
    border: none;
    cursor: pointer;
}

.mobile-menu-btn span {
    display: block;
    width: 24px;
    height: 2px;
    background: #374151;
    transition: 0.3s;
}

/* Mobile Responsive */
@media (max-width: 1024px) {
    .main-nav {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: #fff;
        border-top: 1px solid #e5e7eb;
        box-shadow: 0 4px 6px rgba(0,0,0,0.1);
        padding: 1rem;
    }
    
    .main-nav.active {
        display: block;
    }
    
    .nav-list {
        flex-direction: column;
        gap: 0;
    }
    
    .nav-link {
        padding: 0.75rem 1rem;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .mobile-menu-btn.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .mobile-menu-btn.active span:nth-child(2) {
        opacity: 0;
    }
    
    .mobile-menu-btn.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }
    
    .dropdown-menu {
        position: static;
        box-shadow: none;
        background: #f9fafb;
        border-radius: 0;
        display: none;
        padding-left: 1rem;
    }
    
    .nav-item.dropdown.active .dropdown-menu {
        display: block;
    }
}