:root {
    --primary: #1e4b69;
    --accent: rgb(70, 180, 200);
    --bg: #f5f7fa;
    --write-color: #e74c3c;
    --read-color: #2980b9;
    --sync-color: #27ae60;
}

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

body {
    font-family: 'Segoe UI', system-ui, sans-serif;
    background: var(--bg);
    color: #333;
    padding: 20px;
    display: flex;
    justify-content: center;
}

.container {
    max-width: 900px;
    width: 100%;
}

h1 {
    color: var(--primary);
    text-align: center;
    font-size: 1.6rem;
    margin-bottom: 4px;
}

.subtitle {
    text-align: center;
    color: #666;
    margin-bottom: 20px;
    font-size: 0.95rem;
}

.toggle-bar {
    display: flex;
    justify-content: center;
    gap: 12px;
    margin-bottom: 24px;
}

.toggle-btn {
    padding: 10px 28px;
    border: 2px solid var(--primary);
    border-radius: 8px;
    background: white;
    color: var(--primary);
    font-weight: 700;
    cursor: pointer;
    transition: all 0.25s;
    font-size: 0.95rem;
}

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

.toggle-btn.active[data-mode="write"] {
    background: var(--write-color);
    border-color: var(--write-color);
    color: white;
}

.toggle-btn.active[data-mode="read"] {
    background: var(--read-color);
    border-color: var(--read-color);
    color: white;
}

.architecture-area {
    background: white;
    border-radius: 12px;
    padding: 40px 30px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    position: relative;
    min-height: 300px;
}

.arch-layout {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}

.node {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
    transition: opacity 0.4s, transform 0.4s;
}

.node.dimmed {
    opacity: 0.25;
}

.node-box {
    padding: 16px 20px;
    border-radius: 12px;
    text-align: center;
    border: 2px solid #dce3e8;
    background: white;
    min-width: 120px;
    transition: all 0.4s;
}

.node-box.active-write {
    border-color: var(--write-color);
    box-shadow: 0 0 20px rgba(231, 76, 60, 0.2);
    background: #fdf2f0;
}

.node-box.active-read {
    border-color: var(--read-color);
    box-shadow: 0 0 20px rgba(41, 128, 185, 0.2);
    background: #f0f5fa;
}

.node-box.active-sync {
    border-color: var(--sync-color);
    box-shadow: 0 0 20px rgba(39, 174, 96, 0.2);
    background: #f0faf4;
}

.node-icon {
    font-size: 2rem;
    margin-bottom: 4px;
}

.node-label {
    font-weight: 700;
    color: var(--primary);
    font-size: 0.95rem;
}

.node-sublabel {
    font-size: 0.78rem;
    color: #888;
}

.connection {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    flex: 1;
    min-width: 60px;
    transition: opacity 0.4s;
}

.connection.dimmed {
    opacity: 0.15;
}

.conn-line {
    height: 3px;
    width: 100%;
    background: #ddd;
    border-radius: 2px;
    position: relative;
    overflow: hidden;
    transition: background 0.4s;
}

.conn-line.active-write {
    background: var(--write-color);
}

.conn-line.active-read {
    background: var(--read-color);
}

.conn-line.active-sync {
    background: var(--sync-color);
}

.conn-line .pulse {
    position: absolute;
    top: 0;
    left: -30%;
    width: 30%;
    height: 100%;
    background: rgba(255, 255, 255, 0.6);
    animation: pulse-move 1.5s infinite;
}

@keyframes pulse-move {
    0% { left: -30%; }
    100% { left: 130%; }
}

.conn-label {
    font-size: 0.72rem;
    color: #999;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.replicas-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.sync-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.metrics-bar {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-top: 20px;
    flex-wrap: wrap;
}

.metric {
    background: white;
    border-radius: 10px;
    padding: 14px 20px;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
    min-width: 140px;
    transition: all 0.3s;
}

.metric-value {
    font-size: 1.3rem;
    font-weight: 800;
    color: var(--primary);
}

.metric-label {
    font-size: 0.8rem;
    color: #888;
    margin-top: 2px;
}

@media (max-width: 700px) {
    .arch-layout {
        flex-direction: column;
    }

    .connection {
        min-width: unset;
        width: 80%;
    }

    .conn-line {
        height: 3px;
        width: 100%;
    }
}