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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Inter', sans-serif;
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 30%, #0f4c75 100%);
    color: #333;
    line-height: 1.6;
    min-height: 100vh;
}

.hero {
    text-align: center;
    padding: 0.8rem 1rem 0.6rem;
    background: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(20px);
    color: white;
    border-bottom: 2px solid rgba(255, 215, 0, 0.6);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    min-width: 320px;
}

.progress-container {
    max-width: 300px;
    margin: 1rem auto 0;
    background: rgba(255,255,255,0.2);
    height: 6px;
    border-radius: 3px;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, #ffd700, #ffeb3b);
    border-radius: 3px;
    transition: width 0.3s ease;
    width: 0%;
}

.century-timeline {
    max-width: 600px;
    margin: 0.6rem auto 0;
    padding: 0 1rem;
    position: relative;
}

.timeline-line {
    position: relative;
    height: 12px;
    margin: 0;
    display: flex;
    align-items: center;
}

.timeline-segments {
    width: 100%;
    height: 100%;
    position: relative;
    border-radius: 6px;
    overflow: hidden;
    background: linear-gradient(90deg, rgba(255,255,255,0.2), rgba(255,255,255,0.3), rgba(255,255,255,0.2));
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.timeline-segment {
    position: absolute;
    top: 0;
    height: 100%;
    background: linear-gradient(135deg, #e3f2fd, #bbdefb);
    border-right: 1px solid rgba(255, 255, 255, 0.4);
    transition: all 0.3s ease;
    cursor: pointer;
}

.timeline-segment:last-child {
    border-right: none;
}

.timeline-segment:hover {
    background: linear-gradient(135deg, #fff3e0, #ffcc02);
    transform: scaleY(1.2);
    z-index: 2;
}

.timeline-segment.active {
    background: linear-gradient(135deg, #ff4757, #ff3742);
    transform: scaleY(1.4);
    z-index: 3;
    box-shadow: 0 2px 8px rgba(255, 71, 87, 0.6);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

.nav-link {
    color: rgba(255, 255, 255, 0.9);
    text-decoration: none;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    transition: all 0.3s ease;
    font-weight: 500;
}

.nav-link:hover {
    background: rgba(255, 255, 255, 0.2);
    color: #ffd700;
    transform: translateY(-1px);
}

.nav-divider {
    color: rgba(255, 255, 255, 0.5);
    margin: 0 0.3rem;
}

.nav-current {
    color: #ffd700;
    font-weight: 700;
    padding: 0.3rem 0.8rem;
}

.century-markers {
    position: relative;
    height: 30px;
    margin: 0.5rem 0 0 0;
    width: 100%;
}

.century-marker {
    position: absolute;
    display: flex;
    flex-direction: column;
    align-items: center;
    transform: translateX(-50%);
}

.century-tick {
    width: 2px;
    height: 8px;
    background: rgba(255, 255, 255, 0.6);
    border-radius: 1px;
}

.century-label {
    font-size: 0.7rem;
    color: rgba(255, 255, 255, 0.8);
    margin-top: 0.3rem;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.5);
    font-weight: 500;
    white-space: nowrap;
}

.timeline-markers {
    display: contents;
}

.century-mark {
    display: flex;
    flex-direction: column;
    align-items: center;
    min-width: 40px;
    transition: all 0.3s ease;
    opacity: 0.6;
}

.century-mark.active {
    opacity: 1;
    transform: scale(1.1);
}

.century-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.4);
    margin-bottom: 0.3rem;
    transition: all 0.3s ease;
}

.century-mark.active .century-dot {
    background: #ffd700;
    box-shadow: 0 0 10px rgba(255, 215, 0, 0.6);
    width: 12px;
    height: 12px;
}

.century-label {
    font-size: 0.7rem;
    color: rgba(255, 255, 255, 0.7);
    font-weight: 500;
    text-align: center;
    transition: all 0.3s ease;
}

.century-mark.active .century-label {
    color: #ffd700;
    font-weight: 700;
    text-shadow: 0 0 5px rgba(255, 215, 0, 0.3);
}

.hero h1 {
    font-size: clamp(1.4rem, 3vw, 2rem);
    margin-bottom: 0.3rem;
    text-shadow: 3px 3px 12px rgba(0,0,0,0.7);
    color: #fff;
    font-weight: 800;
    letter-spacing: -0.02em;
    background: linear-gradient(45deg, #ffd700, #ffeb3b, #fff, #ffd700);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    filter: drop-shadow(2px 2px 4px rgba(0,0,0,0.5));
}

.hero p {
    font-size: 0.9rem;
    opacity: 0.95;
    max-width: 500px;
    margin: 0 auto 0.6rem;
    text-shadow: 2px 2px 6px rgba(0,0,0,0.7);
    font-weight: 500;
}

.timeline-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 1rem 1rem 2rem;
    position: relative;
}

.timeline {
    position: relative;
}

.timeline-item {
    margin-bottom: 4rem;
    position: relative;
}

.timeline-card {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 24px;
    padding: 2rem;
    box-shadow: 0 8px 32px rgba(0,0,0,0.1), 0 0 0 1px rgba(255,255,255,0.2);
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(10px);
}

.timeline-card:hover {
    transform: translateY(-8px) scale(1.02);
    box-shadow: 0 20px 60px rgba(0,0,0,0.15);
}

.period-emoji {
    font-size: 2.5rem;
    margin-right: 1rem;
    filter: drop-shadow(0 2px 4px rgba(0,0,0,0.1));
}

.period-header {
    display: flex;
    align-items: center;
    margin-bottom: 1.5rem;
}

.period-title {
    display: flex;
    align-items: center;
    flex: 1;
}

.period-name {
    font-size: 1.6rem;
    font-weight: 800;
    color: #1a1a2e;
    margin-bottom: 0.2rem;
}

.period-subtitle {
    font-size: 1rem;
    color: #666;
    font-weight: 500;
    font-style: italic;
}

.big-question {
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    padding: 1.2rem 1.5rem;
    border-radius: 16px;
    font-size: 1.1rem;
    font-weight: 600;
    margin: 1rem 0;
    box-shadow: 0 4px 20px rgba(102, 126, 234, 0.3);
    position: relative;
}

.big-question::before {
    content: "💭 ";
    font-size: 1.3rem;
    margin-right: 0.5rem;
}

.sticky-idea {
    background: linear-gradient(135deg, #ffd700, #ffeb3b);
    color: #333;
    padding: 1rem 1.2rem;
    border-radius: 12px;
    font-weight: 700;
    font-size: 1.05rem;
    margin: 1rem 0 0.5rem;
    box-shadow: 0 4px 15px rgba(255, 215, 0, 0.3);
    text-align: center;
}

.learn-more-hint {
    text-align: center;
    color: #aaa;
    font-size: 0.8rem;
    margin-bottom: 1rem;
    opacity: 0.7;
}

.claim-item {
    padding: 0.6rem 0;
    margin: 0.3rem 0;
    border-left: 3px solid #667eea;
    padding-left: 1rem;
    transition: all 0.3s ease;
    color: #444;
    line-height: 1.5;
}

.claim-item:hover {
    border-left-color: #764ba2;
    padding-left: 1.2rem;
    color: #333;
}

.connections-section {
    margin: 1.5rem 0;
    padding-left: 1rem;
    border-left: 3px solid #4caf50;
}

.connections-section .detail-title {
    color: #2e7d32;
}

.connection-content {
    color: #555;
    font-style: italic;
    line-height: 1.6;
}

.quick-quiz {
    margin-top: 1.5rem;
    padding-left: 1rem;
    border-left: 4px solid #ff9800;
    background: rgba(255, 152, 0, 0.05);
    padding: 1rem 1rem 1rem 1.5rem;
    border-radius: 0 8px 8px 0;
}

.quiz-question {
    font-weight: 600;
    color: #e65100;
    font-style: italic;
}

.timeline-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 6px;
    background: linear-gradient(90deg, #ff6b6b 0%, #ffa726 50%, #ff8a65 100%);
    border-radius: 20px 20px 0 0;
}

.timeline-item:nth-child(even) .timeline-card::before {
    background: linear-gradient(90deg, #4ecdc4 0%, #45b7af 50%, #26d0ce 100%);
}

.timeline-item:nth-child(3n) .timeline-card::before {
    background: linear-gradient(90deg, #96ceb4 0%, #85c1a3 50%, #74b39a 100%);
}

.timeline-item:nth-child(4n) .timeline-card::before {
    background: linear-gradient(90deg, #feca57 0%, #ff9ff3 50%, #f368e0 100%);
}

.period-header {
    display: flex;
    justify-content: flex-start;
    align-items: center;
    margin-bottom: 1rem;
}

.period-title {
    flex: 1;
}

.period-name {
    font-size: 1.5rem;
    font-weight: bold;
    color: #2c3e50;
    display: inline;
    margin-right: 0.5rem;
}

.period-subtitle {
    font-size: 1.1rem;
    color: #7f8c8d;
    font-style: italic;
    font-weight: 500;
    display: inline;
}

.context-info {
    margin: 1rem 0 1.5rem 0;
    color: #666;
    font-size: 0.95rem;
    line-height: 1.6;
    font-style: italic;
}

.context-info::before {
    content: "🌍 ";
    font-size: 1.1rem;
    margin-right: 0.5rem;
}

.context-info .context-text {
    font-weight: 500;
    color: #555;
}

.key-questions {
    background: #fff3cd;
    border-left: 5px solid #f39c12;
    padding: 1.2rem;
    margin: 1.5rem 0;
    border-radius: 0 15px 15px 0;
    font-style: italic;
    font-weight: 600;
    color: #8b4513;
    box-shadow: 0 4px 20px rgba(243, 156, 18, 0.2);
}

.key-questions::before {
    content: "❓ ";
    font-size: 1.4rem;
    margin-right: 0.5rem;
}

.key-figures {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin: 1rem 0;
}

.figure-tag {
    background: #e8f4f8;
    color: #1565c0;
    padding: 0.4rem 1rem;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    border: 2px solid #81d4fa;
    transition: all 0.3s ease;
}

.figure-tag.clickable {
    cursor: pointer;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: 2px solid #667eea;
    position: relative;
    overflow: hidden;
}

.figure-tag.clickable::before {
    content: '👆';
    position: absolute;
    top: -20px;
    right: 5px;
    font-size: 0.7rem;
    opacity: 0;
    transition: all 0.3s ease;
}

.figure-tag.clickable:hover::before {
    opacity: 1;
    top: -15px;
}

.figure-tag:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(21, 101, 192, 0.3);
    background: #b3e5fc;
    color: #0d47a1;
}

.figure-tag.clickable:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
    background: linear-gradient(135deg, #764ba2 0%, #667eea 100%);
}

.details {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.details.expanded {
    max-height: 1000px;
    padding-top: 1rem;
}

.detail-section {
    margin-bottom: 1.5rem;
}

.detail-title {
    font-weight: 700;
    color: #2c3e50;
    margin-bottom: 0.8rem;
    font-size: 1.1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.detail-content {
    color: #555;
    font-size: 0.95rem;
    line-height: 1.7;
}

.expand-btn {
    background: transparent;
    border: 2px solid #667eea;
    color: #667eea;
    font-weight: 600;
    cursor: pointer;
    margin-top: 1.5rem;
    font-size: 0.9rem;
    padding: 0.8rem 1.5rem;
    border-radius: 25px;
    transition: all 0.3s ease;
    width: 100%;
}

.expand-btn:hover {
    background: #667eea;
    color: white;
    transform: translateY(-1px);
}

.today-echo {
    background: linear-gradient(90deg, #74b9ff, #0984e3);
    color: white;
    padding: 1.2rem 1.5rem;
    border-radius: 12px;
    margin: 1.5rem 0;
    box-shadow: 0 4px 15px rgba(116, 185, 255, 0.25);
    font-weight: 500;
}

@media (max-width: 768px) {
    .hero {
        padding: 0.6rem 1rem 0.5rem;
        background: rgba(0, 0, 0, 0.5);
        border-bottom: 2px solid rgba(255, 215, 0, 0.7);
    }
    
    .hero h1 {
        font-size: 1.3rem;
        margin-bottom: 0.3rem;
        text-shadow: 2px 2px 8px rgba(0,0,0,0.8);
    }
    
    .hero p {
        font-size: 0.8rem;
        line-height: 1.4;
        font-weight: 500;
        margin-bottom: 0.4rem;
        text-shadow: 2px 2px 6px rgba(0,0,0,0.7);
    }
    
    .progress-container {
        max-width: 200px;
        margin: 0.6rem auto 0;
        height: 4px;
    }
    
    .century-timeline {
        max-width: 100%;
        margin: 0.5rem auto 0;
        padding: 0 0.8rem;
    }
    
    .timeline-line {
        height: 10px;
        margin: 0;
    }
    
    .timeline-segments {
        width: 100%;
    }
    
    .century-markers {
        height: 25px;
        margin: 0.4rem 0 0 0;
    }
    
    .timeline-segment:hover {
        transform: scaleY(1.1);
    }
    
    .timeline-segment.active {
        transform: scaleY(1.3);
    }
    
    .century-tick {
        width: 1px;
        height: 6px;
    }
    
    .century-label {
        font-size: 0.6rem;
        margin-top: 0.2rem;
    }
    
    .century-label {
        font-size: 0.6rem;
        margin-top: 0.2rem;
    }
    
    .timeline-container {
        padding: 0.8rem 0.8rem 1.5rem;
    }
    
    .timeline-item {
        margin-bottom: 2rem;
    }
    
    .timeline-card {
        padding: 1rem;
        border-radius: 16px;
    }
    
    .period-header {
        flex-direction: row;
        align-items: center;
        margin-bottom: 0.8rem;
        justify-content: flex-start;
    }
    
    .period-title {
        display: flex;
        flex-direction: row;
        align-items: center;
        flex: 1;
    }
    
    .period-emoji {
        font-size: 1.8rem;
        margin-right: 0.8rem;
    }
    
    .period-name {
        font-size: 1.2rem;
        margin-bottom: 0;
        margin-right: 0.5rem;
        display: inline;
    }
    
    .period-subtitle {
        font-size: 0.85rem;
        display: inline;
    }

    .big-question {
        padding: 0.8rem 1rem;
        font-size: 1rem;
        margin: 0.8rem 0;
        border-radius: 12px;
    }

    .sticky-idea {
        padding: 0.6rem 0.8rem;
        font-size: 0.95rem;
        margin: 0.6rem 0 0.3rem;
    }

    .learn-more-hint {
        font-size: 0.75rem;
        margin-bottom: 0.8rem;
    }

    .context-info {
        margin: 0.6rem 0 0.8rem 0;
        font-size: 0.85rem;
    }

    .key-figures {
        gap: 0.25rem;
        margin: 0.6rem 0;
    }

    .figure-tag {
        padding: 0.2rem 0.5rem;
        font-size: 0.75rem;
    }

    .detail-section {
        margin-bottom: 0.8rem;
    }

    .detail-title {
        font-size: 1rem;
        margin-bottom: 0.6rem;
    }

    .detail-content {
        font-size: 0.9rem;
        line-height: 1.6;
    }

    .claim-item {
        padding: 0.4rem 0;
        margin: 0.2rem 0;
        font-size: 0.9rem;
        padding-left: 0.8rem;
    }

    .connections-section {
        margin: 0.8rem 0;
        padding-left: 0.6rem;
    }

    .quick-quiz {
        margin-top: 0.8rem;
        padding: 0.6rem 0.6rem 0.6rem 1rem;
    }

    .quiz-question {
        font-size: 0.9rem;
    }

    .today-echo {
        padding: 0.8rem 1rem;
        margin: 0.8rem 0;
        font-size: 0.9rem;
    }

    .expand-btn {
        padding: 0.5rem 1rem;
        font-size: 0.8rem;
        margin-top: 0.8rem;
    }
}

/* Policy Footer Styles for AdSense Compliance */
.policy-footer {
    background: linear-gradient(135deg, #2c2c54 0%, #1a1a2e 100%);
    color: #e8e8e8;
    padding: 2rem 1rem;
    margin-top: 3rem;
    border-top: 3px solid rgba(255, 215, 0, 0.3);
}

.policy-content {
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.7;
}

.policy-content h3 {
    color: #ffd700;
    margin-bottom: 1.5rem;
    font-size: 1.4rem;
    text-align: center;
}

.policy-content p {
    margin-bottom: 1.2rem;
    font-size: 0.95rem;
}

.policy-content strong {
    color: #ffd700;
    font-weight: 600;
}

.policy-content a {
    color: #64b5f6;
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: all 0.3s ease;
}

.policy-content a:hover {
    color: #ffd700;
    border-bottom-color: #ffd700;
}

@media (max-width: 768px) {
    .policy-footer {
        padding: 1.5rem 1rem;
        margin-top: 2rem;
    }
    
    .policy-content h3 {
        font-size: 1.2rem;
        margin-bottom: 1rem;
    }
    
    .policy-content p {
        font-size: 0.9rem;
        margin-bottom: 1rem;
    }
}