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

body {
    font-family: 'Segoe UI', system-ui, sans-serif;
    background: #f5f7fa;
    color: #333;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: 20px;
}

.container {
    max-width: 860px;
    width: 100%;
}

h1 {
    color: #1e4b69;
    text-align: center;
    font-size: 1.8rem;
    margin-bottom: 4px;
}

.subtitle {
    text-align: center;
    color: #666;
    font-size: 0.95rem;
    margin-bottom: 28px;
}

.timeline {
    position: relative;
    padding: 40px 0 20px;
    margin-bottom: 24px;
}

.timeline-track {
    position: absolute;
    top: 50%;
    left: 5%;
    right: 5%;
    height: 4px;
    background: linear-gradient(to right, #1e4b69, #2e86c1, #27ae60);
    border-radius: 2px;
    transform: translateY(-50%);
}

.feedback-loop {
    position: absolute;
    top: 4px;
    left: 10%;
    right: 10%;
    height: 30px;
}

.feedback-loop svg {
    width: 100%;
    height: 100%;
}

.feedback-label {
    position: absolute;
    top: -2px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 0.7rem;
    color: #1e4b69;
    opacity: 0.5;
    white-space: nowrap;
    font-style: italic;
}

.iterations {
    display: flex;
    justify-content: space-between;
    position: relative;
    padding: 0 3%;
}

.iteration {
    display: flex;
    flex-direction: column;
    align-items: center;
    cursor: pointer;
    position: relative;
    z-index: 2;
    flex: 1;
}

.iter-marker {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 8px;
}

.iter-dot {
    width: 18px;
    height: 18px;
    background: #1e4b69;
    border-radius: 50%;
    border: 3px solid #fff;
    box-shadow: 0 0 0 2px #1e4b69;
    transition: transform 0.2s, box-shadow 0.2s;
}

.iteration:hover .iter-dot {
    transform: scale(1.3);
    box-shadow: 0 0 0 3px #2e86c1, 0 0 12px rgba(46, 134, 193, 0.4);
}

.iteration.active .iter-dot {
    background: #27ae60;
    box-shadow: 0 0 0 3px #27ae60, 0 0 12px rgba(39, 174, 96, 0.4);
    transform: scale(1.3);
}

.iter-version {
    font-size: 0.7rem;
    font-weight: 700;
    color: #1e4b69;
    margin-top: 4px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.iter-card {
    background: #fff;
    border-radius: 8px;
    padding: 10px 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    text-align: center;
    transition: transform 0.2s, box-shadow 0.2s;
    width: 100%;
    max-width: 130px;
}

.iteration:hover .iter-card {
    transform: translateY(-4px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.12);
}

.iteration.active .iter-card {
    border: 2px solid #27ae60;
}

.iter-title {
    font-size: 0.8rem;
    font-weight: 700;
    color: #1e4b69;
    margin-bottom: 4px;
}

.iter-users {
    font-size: 0.7rem;
    color: #888;
}

.detail-panel {
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 2px 16px rgba(0, 0, 0, 0.08);
    overflow: hidden;
    display: none;
    animation: slideUp 0.3s ease;
}

.detail-panel.active {
    display: block;
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(16px); }
    to { opacity: 1; transform: translateY(0); }
}

.detail-header {
    padding: 16px 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    color: #fff;
}

.detail-header h2 {
    font-size: 1.2rem;
}

.detail-badge {
    background: rgba(255, 255, 255, 0.2);
    padding: 4px 14px;
    border-radius: 14px;
    font-size: 0.8rem;
    font-weight: 500;
}

.detail-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    padding: 20px 24px;
}

.detail-section {
    padding: 0;
}

.detail-section h3 {
    color: #1e4b69;
    font-size: 0.95rem;
    margin-bottom: 8px;
    border-bottom: 2px solid #f0f0f0;
    padding-bottom: 4px;
}

.detail-section ul {
    list-style: none;
    padding: 0;
}

.detail-section li {
    padding: 4px 0 4px 18px;
    position: relative;
    font-size: 0.85rem;
    color: #555;
    line-height: 1.4;
}

.detail-section li::before {
    content: '+';
    position: absolute;
    left: 2px;
    color: #27ae60;
    font-weight: 700;
}

.lesson-section {
    grid-column: 1 / -1;
    background: #f0f7fc;
    padding: 14px 16px;
    border-radius: 8px;
    border-left: 3px solid #2e86c1;
}

.lesson-section h3 {
    border-bottom: none;
    padding-bottom: 0;
}

.lesson-section p {
    color: #555;
    font-size: 0.9rem;
    line-height: 1.6;
    font-style: italic;
}

.metric-item {
    display: flex;
    justify-content: space-between;
    padding: 6px 0;
    border-bottom: 1px solid #f5f5f5;
    font-size: 0.85rem;
}

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

.metric-label {
    color: #888;
}

.metric-value {
    font-weight: 700;
    color: #1e4b69;
}

@media (max-width: 600px) {
    .iterations {
        flex-wrap: wrap;
        gap: 12px;
        justify-content: center;
    }

    .iteration {
        flex: 0 0 auto;
    }

    .timeline-track {
        display: none;
    }

    .feedback-loop {
        display: none;
    }

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

    h1 { font-size: 1.3rem; }
}