/* CSS Variables and Theme */
:root {
    /* Primary Scientific Palette - Updated with Mustard Yellow */
    --primary-navy: #1a2332;
    --primary-mustard: #d4a845;
    --secondary-teal: #3d7c7c;
    --accent-gold: #e6b84a;
    --accent-warm: #c7956d;
    
    /* Neutral Sophistication */
    --light-cream: #faf8f4;
    --warm-white: #ffffff;
    --soft-gray: #f5f3f0;
    --border-subtle: #e8e4de;
    --text-primary: #2c2c2c;
    --text-secondary: #5a5a5a;
    --text-muted: #888888;
    
    /* Shadows & Effects */
    --shadow-soft: 0 4px 20px rgba(26, 35, 50, 0.08);
    --shadow-medium: 0 8px 30px rgba(26, 35, 50, 0.12);
    --shadow-strong: 0 15px 50px rgba(26, 35, 50, 0.2);
    
    /* Typography Scale */
    --font-display: 'Playfair Display', serif;
    --font-body: 'Source Sans Pro', sans-serif;
    
    /* Border Radius Scale - More rounded */
    --radius-small: 12px;
    --radius-medium: 20px;
    --radius-large: 28px;
    --radius-xl: 35px;
}

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-body);
    background: linear-gradient(135deg, var(--light-cream) 0%, var(--warm-white) 100%);
    color: var(--text-primary);
    line-height: 1.7;
    overflow-x: hidden;
}

/* Background Geometric Pattern */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 20%, rgba(61, 124, 124, 0.03) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(212, 175, 55, 0.03) 0%, transparent 50%),
        linear-gradient(45deg, transparent 49%, rgba(45, 74, 107, 0.01) 50%, transparent 51%);
    pointer-events: none;
    z-index: -1;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    position: relative;
    z-index: 1;
}

/* Header */
.header {
    background: var(--primary-mustard);
    color: white;
    padding: 2rem 0;
    position: relative;
    overflow: hidden;
    border-bottom: 1px solid rgba(26, 35, 50, 0.15);
    box-shadow: 0 2px 10px rgba(26, 35, 50, 0.1);
}

.header::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 120%;
    height: 200%;
    background: radial-gradient(ellipse, rgba(26, 35, 50, 0.1) 0%, transparent 70%);
    transform: rotate(-15deg);
}

.header-symbols {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1;
}

.math-symbol {
    position: absolute;
    color: white;
    font-family: var(--font-display);
    font-weight: 700;
    line-height: 1;
    user-select: none;
}

.header-content {
    text-align: center;
    position: relative;
    z-index: 2;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.header h1 {
    font-family: var(--font-body);
    font-size: clamp(2.8rem, 5.5vw, 4.5rem);
    font-weight: 600;
    margin-bottom: 0;
    text-shadow: 2px 2px 4px rgba(26, 35, 50, 0.3);
    letter-spacing: 0.5px;
    color: white;
}

.header .subtitle {
    font-size: 1.3rem;
    font-weight: 300;
    opacity: 0.9;
    max-width: 600px;
    margin: 0 auto;
}

.header .math-accent {
    font-family: var(--font-display);
    color: var(--accent-gold);
    font-style: italic;
}

/* Topic Navigation Bar */
.topic-nav-container {
    background: linear-gradient(135deg, var(--soft-gray) 0%, var(--warm-white) 100%);
    border-bottom: 1px solid var(--border-subtle);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 101;
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.topic-nav-container .container {
    max-width: 1400px;
    padding: 0 1.5rem;
}

.topic-nav {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
}

.topic-nav-layout {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.9rem;
    min-height: 56px;
}

.topic-nav-search-wrap {
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: min(340px, 38vw);
    flex: 0 0 auto;
}

.topic-nav-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.8rem 1.5rem;
    background: var(--warm-white);
    border: 2px solid var(--border-subtle);
    border-radius: var(--radius-medium);
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.topic-nav-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(212, 168, 69, 0.1), transparent);
    transition: left 0.5s ease;
}

.topic-nav-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
    border-color: var(--primary-mustard);
    background: linear-gradient(135deg, var(--warm-white), var(--soft-gray));
}

.topic-nav-item:hover::before {
    left: 100%;
}

.topic-nav-item.active {
    background: var(--primary-mustard);
    color: white;
    border-color: var(--primary-mustard);
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(212, 168, 69, 0.3);
}

.topic-nav-item i {
    font-size: 1.1rem;
}

/* Breadcrumb Navigation */
.breadcrumb-container {
    background: var(--warm-white);
    border-bottom: 2px solid var(--border-subtle);
    padding: 1rem 0;
    position: sticky;
    top: 76px;
    z-index: 100;
    backdrop-filter: blur(10px);
    box-shadow: none;
}

.breadcrumb-container .container {
    max-width: 1400px;
    padding-left: calc(1.5rem + 160px + 1.2rem);
    padding-right: 1.5rem;
}

.breadcrumb {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    font-family: var(--font-body);
    font-size: 0.95rem;
    font-weight: 400;
}

.breadcrumb-item {
    color: var(--text-muted);
    text-decoration: none;
    padding: 0.4rem 0.8rem;
    border-radius: var(--radius-small);
    transition: all 0.3s ease;
    position: relative;
}

.breadcrumb-item:hover {
    color: var(--primary-mustard);
    background: var(--soft-gray);
}

.breadcrumb-item.current {
    color: var(--primary-navy);
    font-weight: 500;
    background: var(--soft-gray);
}

.breadcrumb-separator {
    color: var(--border-subtle);
    font-size: 0.8rem;
    user-select: none;
}

.breadcrumb-layout {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    gap: 0.9rem;
}

.breadcrumb-search {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    width: 100%;
    padding: 0.5rem 0.75rem;
    background: var(--soft-gray);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-small);
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.breadcrumb-search:focus-within {
    border-color: var(--primary-mustard);
    box-shadow: 0 0 0 3px rgba(212, 168, 69, 0.18);
}

.breadcrumb-search i {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.topic-search-input {
    width: 100%;
    border: none;
    background: transparent;
    color: var(--primary-navy);
    font-size: 0.9rem;
    outline: none;
}

.search-results {
    position: absolute;
    top: calc(100% + 0.45rem);
    left: 0;
    width: 100%;
    background: var(--warm-white);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-medium);
    box-shadow: var(--shadow-medium);
    overflow: hidden;
    z-index: 120;
}

.search-result-item {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.1rem;
    width: 100%;
    background: transparent;
    border: none;
    border-bottom: 1px solid var(--border-subtle);
    padding: 0.75rem 0.9rem;
    text-align: left;
    cursor: pointer;
}

.search-result-item:last-child {
    border-bottom: none;
}

.search-result-item:hover {
    background: var(--soft-gray);
}

.search-result-item:focus-visible {
    outline: 2px solid var(--primary-mustard);
    outline-offset: -2px;
}

.search-result-title {
    color: var(--primary-navy);
    font-size: 0.88rem;
    font-weight: 600;
}

.search-result-path {
    color: var(--text-secondary);
    font-size: 0.76rem;
}

.search-result-empty {
    padding: 0.8rem 0.9rem;
    color: var(--text-muted);
    font-size: 0.82rem;
}

/* Main Content Area with Sidebars */
.main-content {
    padding: 0;
    min-height: 60vh;
    display: flex;
    gap: 1.2rem;
    max-width: 1400px;
    margin: 0 auto;
    padding-left: 1.5rem;
    padding-right: 1.5rem;
    align-items: flex-start;
    padding-top: 1.5rem;
}

.sidebar-left {
    width: 160px;
    flex-shrink: 0;
}

.content-center {
    flex: 1;
    min-width: 0;
}

.sidebar-right {
    width: 200px;
    flex-shrink: 0;
}

/* Content Header - Remove extra margin to align with sidebars */
.content-header {
    display: none;
}

/* Left Control Panel */
.control-panel {
    position: sticky;
    top: 160px;
    display: flex;
    flex-direction: column;
    gap: 0.9rem;
    max-height: calc(100vh - 180px);
    overflow-y: auto;
    padding-right: 0.25rem;
}

.panel-section {
    background: var(--warm-white);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-medium);
    box-shadow: 0 2px 8px rgba(26, 35, 50, 0.06);
    padding: 0.75rem;
}

.panel-title {
    margin: 0 0 0.55rem;
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.45px;
    color: var(--text-muted);
    font-weight: 700;
}

.quick-link-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 0.5rem;
}

.quick-link-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    width: 100%;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-small);
    background: var(--soft-gray);
    color: var(--primary-navy);
    text-decoration: none;
    padding: 0.55rem 0.6rem;
    font-size: 0.82rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.25s ease;
}

.quick-link-btn i {
    color: var(--primary-mustard);
    font-size: 1rem;
}

.quick-link-btn:hover {
    border-color: var(--primary-mustard);
    transform: translateX(2px);
    box-shadow: 0 3px 8px rgba(212, 168, 69, 0.2);
}

/* Formula Cheatsheet Sidebar - Start at same level as content */
.formula-cheatsheet {
    position: sticky;
    top: 160px;
    max-height: calc(100vh - 180px);
    overflow-y: auto;
    padding-left: 0.5rem;
}

.formula-cheatsheet h3 {
    display: none;
}

.formula-link-list {
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
}

.formula-link-btn {
    display: flex;
    align-items: center;
    gap: 0.55rem;
    width: 100%;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-small);
    background: var(--warm-white);
    color: var(--primary-navy);
    padding: 0.62rem 0.7rem;
    font-size: 0.82rem;
    font-weight: 600;
    text-align: left;
    cursor: pointer;
    transition: all 0.25s ease;
}

.formula-link-btn i {
    color: var(--primary-mustard);
    font-size: 0.95rem;
}

.formula-link-btn:hover {
    border-color: var(--primary-mustard);
    box-shadow: 0 3px 10px rgba(212, 168, 69, 0.18);
    transform: translateY(-1px);
}

.formula-link-btn.active {
    background: var(--primary-mustard);
    border-color: var(--primary-mustard);
    color: white;
}

.formula-link-btn.active i {
    color: white;
}

.formula-link-note {
    margin: 0.15rem 0 0;
    font-size: 0.72rem;
    color: var(--text-muted);
}

.formula-item {
    background: var(--warm-white);
    border-radius: var(--radius-small);
    padding: 0.6rem 0.75rem;
    margin-bottom: 0.6rem;
    border-left: 3px solid var(--primary-mustard);
    box-shadow: 0 2px 8px rgba(26, 35, 50, 0.06);
    border: 1px solid var(--border-subtle);
}

.formula-item:last-child {
    margin-bottom: 0;
}

.formula-title {
    font-weight: 600;
    font-size: 0.75rem;
    color: var(--primary-navy);
    margin-bottom: 0.3rem;
    text-transform: uppercase;
    letter-spacing: 0.3px;
}

.formula-content {
    font-size: 0.72rem;
    color: var(--text-secondary);
    overflow-x: hidden;
    word-break: break-word;
    overflow-wrap: break-word;
}

.important-note {
    background: var(--warm-white);
    border-radius: var(--radius-small);
    padding: 0.6rem 0.75rem;
    margin-bottom: 0.6rem;
    border-left: 3px solid var(--secondary-teal);
    box-shadow: 0 2px 8px rgba(26, 35, 50, 0.06);
    border: 1px solid var(--border-subtle);
}

.important-note h4 {
    font-size: 0.8rem;
    color: var(--primary-navy);
    margin-bottom: 0.25rem;
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.important-note p {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin: 0;
}

/* Responsive Design for Sidebars */
@media (max-width: 1200px) {
    .main-content {
        flex-direction: column;
        padding-left: 2rem;
        padding-right: 2rem;
    }
    
    .sidebar-left,
    .sidebar-right {
        width: 100%;
        position: static;
    }
    
    .control-panel,
    .formula-cheatsheet {
        position: static;
        max-height: none;
        padding: 0;
    }

    .control-panel {
        display: grid;
        grid-template-columns: 1fr;
        gap: 1rem;
    }
}

.content-header {
    display: none;
}

.content-title {
    font-family: var(--font-display);
    font-size: 2.5rem;
    font-weight: 500;
    color: var(--primary-navy);
    margin-bottom: 1rem;
}

.content-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Topic Cards Grid */
.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.topic-card {
    background: var(--warm-white);
    border-radius: var(--radius-large);
    padding: 2rem 1.5rem;
    box-shadow: var(--shadow-soft);
    border: 1px solid var(--border-subtle);
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

.topic-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-mustard);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.4s ease;
}

.topic-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-medium);
}

.topic-card:hover::before {
    transform: scaleX(1);
}

.topic-icon {
    width: 50px;
    height: 50px;
    background: var(--primary-mustard);
    border-radius: var(--radius-medium);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.2rem;
    color: white;
    font-size: 1.5rem;
}

.topic-card h3 {
    font-family: var(--font-display);
    font-size: 1.4rem;
    font-weight: 500;
    color: var(--primary-navy);
    margin-bottom: 0.6rem;
    line-height: 1.3;
}

.topic-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.5;
    margin-bottom: 1.2rem;
}

.topic-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.topic-count {
    display: flex;
    align-items: center;
    gap: 0.3rem;
}

.explore-arrow {
    opacity: 0;
    transform: translateX(-10px);
    transition: all 0.3s ease;
}

.topic-card:hover .explore-arrow {
    opacity: 1;
    transform: translateX(0);
}

/* Expanded Content Area */
.expanded-content {
    background: var(--primary-navy);
    color: white;
    padding: 3rem 2rem;
    border-radius: var(--radius-large);
    margin-top: 2rem;
    box-shadow: var(--shadow-strong);
    transform: scaleY(0);
    transform-origin: top;
    transition: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    opacity: 0;
    overflow: hidden;
    position: relative;
}

.expanded-content::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, rgba(230, 184, 74, 0.1) 0%, transparent 70%);
    border-radius: 50%;
    transform: translate(30%, -30%);
}

.expanded-content.show {
    transform: scaleY(1);
    opacity: 1;
}

.expanded-content h2 {
    font-family: var(--font-display);
    font-size: 2.2rem;
    font-weight: 500;
    margin-bottom: 1.5rem;
    color: var(--accent-gold);
}

.expanded-content p {
    font-size: 1.1rem;
    line-height: 1.8;
    opacity: 0.95;
    position: relative;
    z-index: 1;
}

/* Progress Indicator */
/* Footer */
.footer {
    background: var(--primary-navy);
    color: white;
    padding: 3rem 0 2rem;
    margin-top: 4rem;
}

.footer-content {
    text-align: center;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-links a:hover {
    color: var(--accent-gold);
}

.footer-credits {
    font-size: 0.9rem;
    opacity: 0.7;
}

/* Responsive Design */
@media (max-width: 1200px) {
    .topic-nav-layout {
        position: static;
        flex-direction: column;
        align-items: stretch;
        justify-content: flex-start;
        min-height: 0;
        gap: 0.75rem;
    }

    .topic-nav-search-wrap {
        position: relative;
        left: auto;
        top: auto;
        transform: none;
        width: 100%;
    }

    .topic-nav {
        justify-content: flex-start;
        gap: 1rem;
    }

    .breadcrumb-container .container {
        padding-left: 2rem;
    }

    .topics-grid {
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: 1.2rem;
    }
}

@media (max-width: 768px) {
    .header-symbols .math-symbol:nth-child(n + 11) {
        display: none;
    }

    .topic-nav {
        gap: 1rem;
    }

    .topic-nav-layout {
        flex-direction: column;
        align-items: stretch;
        gap: 0.75rem;
    }

    .topic-nav-search-wrap {
        width: 100%;
    }
    
    .topic-nav-item {
        padding: 0.6rem 1rem;
        font-size: 0.85rem;
    }
    
    .breadcrumb-container {
        top: 60px; /* Smaller topic nav on mobile */
    }
    
    .topics-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .breadcrumb {
        font-size: 0.85rem;
        gap: 0.5rem;
    }

    .breadcrumb-search,
    .search-results {
        width: 100%;
    }

    .control-panel {
        grid-template-columns: 1fr;
    }
    
    .header {
        padding: 1.5rem 0;
    }
    
    .topic-card {
        padding: 2rem 1.5rem;
    }
    
    .expanded-content {
        padding: 2rem 1.5rem;
    }

}

/* iPad / Tablet optimization */
@media (min-width: 769px) and (max-width: 1180px) {
    .topic-nav-container .container {
        padding: 0 2rem;
    }

    .topic-nav-layout {
        position: static;
        display: grid;
        grid-template-columns: 1fr;
        min-height: 0;
        gap: 0.8rem;
    }

    .topic-nav-search-wrap {
        position: relative;
        left: auto;
        top: auto;
        transform: none;
        width: min(520px, 100%);
    }

    .topic-nav {
        justify-content: center;
        gap: 0.95rem;
    }

    .topic-nav-item {
        min-height: 48px;
        padding: 0.75rem 1.15rem;
        font-size: 0.95rem;
    }

    .breadcrumb-container .container {
        padding-left: 2rem;
        padding-right: 2rem;
    }

    .main-content {
        padding-left: 2rem;
        padding-right: 2rem;
    }

    .topics-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
        gap: 1.25rem;
    }

    .quick-link-btn {
        min-height: 48px;
        padding: 0.75rem 0.8rem;
    }

    .search-results {
        max-height: 50vh;
        overflow-y: auto;
    }
}

/* Touch devices: avoid sticky hover effects */
@media (hover: none) and (pointer: coarse) {
    .topic-card:hover {
        transform: none;
        box-shadow: var(--shadow-soft);
    }

    .topic-card:hover::before {
        transform: scaleX(0);
    }

    .topic-nav-item:hover,
    .quick-link-btn:hover {
        transform: none;
        box-shadow: none;
    }

    .topic-nav-item:hover::before {
        left: -100%;
    }
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--soft-gray);
    border-radius: var(--radius-small);
}

::-webkit-scrollbar-thumb {
    background: var(--primary-mustard);
    border-radius: var(--radius-small);
}

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

/* MathJax Styling */
.MathJax {
    color: var(--primary-navy) !important;
    max-width: 100% !important;
    overflow-x: hidden !important;
}

.header .MathJax {
    color: var(--primary-navy) !important;
    font-size: 1em !important;
    font-weight: bold !important;
}

/* MathJax in Sidebar-Formelkästen: kleinere Darstellung */
.formula-content .MathJax,
.formula-content mjx-container {
    font-size: 0.82em !important;
    max-width: 100% !important;
    overflow-x: hidden !important;
}

/* MathJax Container nie breiter als Elternelement */
mjx-container {
    max-width: 100% !important;
    overflow-x: hidden !important;
}

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

.topic-card {
    animation: fadeInUp 0.6s ease forwards;
}

.topic-card:nth-child(1) { animation-delay: 0.1s; }
.topic-card:nth-child(2) { animation-delay: 0.2s; }
.topic-card:nth-child(3) { animation-delay: 0.3s; }


/* =============================================
   Detail-Lernseite (z.B. Ableitungsregeln)
   ============================================= */

.detail-page {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    animation: fadeInUp 0.4s ease forwards;
    grid-column: 1 / -1; /* volle Breite im Grid */
}

.detail-section {
    background: var(--warm-white);
    border-radius: var(--radius-large);
    padding: 1.8rem 2rem;
    box-shadow: var(--shadow-soft);
    border: 1px solid var(--border-subtle);
}

.detail-heading {
    font-family: var(--font-display);
    font-size: 1.8rem;
    font-weight: 500;
    color: var(--primary-navy);
    margin-bottom: 0.8rem;
    border-bottom: 2px solid var(--primary-mustard);
    padding-bottom: 0.5rem;
}

.detail-subheading {
    font-family: var(--font-display);
    font-size: 1.2rem;
    font-weight: 500;
    color: var(--primary-navy);
    margin-bottom: 1rem;
}

.detail-intro {
    font-size: 1rem;
    color: var(--text-secondary);
    line-height: 1.75;
    max-width: 800px;
}

/* Konzept-Tabelle (Definition / Bedeutung) */
.concept-table {
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-medium);
    overflow: hidden;
}

.concept-row {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    border-bottom: 1px solid var(--border-subtle);
}

.concept-cell-img {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0.8rem;
}

.concept-img {
    width: 100%;
    max-height: 220px;
    object-fit: contain;
    border-radius: var(--radius-small);
}

.concept-row:last-child {
    border-bottom: none;
}

.concept-header {
    background: var(--soft-gray);
}

.concept-header .concept-cell {
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--primary-navy);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.concept-cell {
    padding: 1.2rem 1.5rem;
    font-size: 0.95rem;
    color: var(--text-secondary);
    border-right: 1px solid var(--border-subtle);
    line-height: 1.6;
}

.concept-cell:last-child {
    border-right: none;
}

.concept-label {
    font-weight: 600;
    color: var(--primary-navy);
    margin-bottom: 0.6rem;
    font-size: 0.9rem;
}

.concept-formula {
    font-size: 1rem;
    color: var(--primary-navy);
}

.concept-note {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-style: italic;
}

/* Ableitungs-Tabelle */
.deriv-table-wrapper {
    overflow-x: auto;
    border-radius: var(--radius-medium);
    border: 1px solid var(--border-subtle);
}

.deriv-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.8rem;
}

.deriv-table td {
    padding: 0.4rem 0.5rem;
    text-align: center;
    border-right: 1px solid var(--border-subtle);
    white-space: nowrap;
    vertical-align: middle;
}

/* Erste Spalte: Zeilenbezeichnung f(x) / f'(x) */
.deriv-table .deriv-label {
    background: #eef3e8;
    color: var(--primary-navy);
    font-weight: 600;
    font-size: 0.9rem;
    border-right: 2px solid #c5d9b0;
    padding: 0.4rem 0.6rem;
    white-space: nowrap;
}

/* Obere Datenzeile f(x): leicht grünlicher Hintergrund */
.deriv-row-fx td {
    background: #f7faf4;
    color: var(--primary-navy);
    font-weight: 500;
    border-bottom: 1px solid var(--border-subtle);
}

/* Untere Datenzeile f'(x): weißer Hintergrund */
.deriv-row-dfx td {
    background: var(--warm-white);
    color: var(--text-secondary);
}

/* kleine Hinweistexte wie (c∈ℝ) */
.deriv-small {
    font-size: 0.72rem;
    color: var(--text-muted);
    display: block;
}

/* Fußzeile mit Regelbezeichnungen */
.deriv-rule-row td {
    padding: 0.3rem 0.9rem 0.7rem;
    text-align: center;
    background: var(--warm-white);
    border-top: none;
    position: relative;
}

.deriv-table .rule-label {
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--text-secondary);
    position: relative;
    display: inline-block;
    padding-top: 0.6rem;
}

/* Klammer-Optik über den Regelbezeichnungen */
.deriv-table .rule-label::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 6px;
    border-left: 2px solid var(--text-muted);
    border-top: 2px solid var(--text-muted);
    border-right: 2px solid var(--text-muted);
    border-radius: 3px 3px 0 0;
}

/* Regel-Karten (Produkt-, Quotienten-, Kettenregel) */
.rules-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.2rem;
    align-items: start;
}

.rule-card {
    background: var(--soft-gray);
    border-radius: var(--radius-medium);
    padding: 1.2rem 1.4rem;
    border: 1px solid var(--border-subtle);
    border-top: 3px solid var(--primary-mustard);
    transition: box-shadow 0.3s ease;
}

.rule-card:hover {
    box-shadow: var(--shadow-medium);
}

.rule-card-title {
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--primary-navy);
    margin-bottom: 0.7rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.rule-card-title i {
    color: var(--primary-mustard);
}

.rule-card-formula {
    font-size: 1rem;
    color: var(--primary-navy);
    margin-bottom: 0.9rem;
    padding: 0.6rem 0.8rem;
    background: var(--warm-white);
    border-radius: var(--radius-small);
    border: 1px solid var(--border-subtle);
}

.rule-card-example {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.example-label {
    font-weight: 600;
    color: var(--secondary-teal);
    display: block;
    margin-bottom: 0.2rem;
}

/* Sidebar Info-Modus (Startseite / Themenebene) */
.sidebar-info-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    font-size: 0.85rem;
    color: var(--primary-navy);
    margin-bottom: 0.4rem;
}

.sidebar-info-header i {
    color: var(--primary-mustard);
    font-size: 1rem;
}

.sidebar-info-hint {
    font-size: 0.75rem;
    color: var(--text-muted);
    line-height: 1.5;
    margin-bottom: 0.6rem;
}

.sidebar-info-label {
    font-size: 0.68rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-muted);
    margin-bottom: 0.4rem;
}

.sidebar-divider {
    height: 1px;
    background: var(--border-subtle);
    margin: 0.7rem 0;
}

.sidebar-hint-item {
    display: flex;
    align-items: flex-start;
    gap: 0.5rem;
    font-size: 0.78rem;
    color: var(--text-secondary);
    padding: 0.35rem 0.5rem;
    border-radius: 8px;
    margin-bottom: 0.25rem;
    background: var(--warm-white);
    border: 1px solid var(--border-subtle);
    line-height: 1.4;
}

.sidebar-hint-item i {
    color: var(--primary-mustard);
    font-size: 0.8rem;
    margin-top: 0.1rem;
    flex-shrink: 0;
}