body {
    background: aliceblue;
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 1rem 1.5rem;
}

h2 {
    text-align: center;
    color: #333;
    margin: 0.25rem 0 0.75rem;
    font-size: 1.3rem;
}

.chart-container {
    position: relative;
    width: 100%;
    max-height: 420px;
}

.controls {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.5rem;
    margin: 0.75rem 0 0.25rem;
}

.controls button {
    padding: 0.4rem 1rem;
    border: 2px solid #3F51B5;
    border-radius: 4px;
    background: white;
    color: #3F51B5;
    font-size: 0.85rem;
    cursor: pointer;
    transition: background 0.2s, color 0.2s;
}

.controls button.active {
    background: #3F51B5;
    color: white;
}

.controls button:hover:not(.active) {
    background: #e8eaf6;
}

.source {
    text-align: center;
    font-size: 0.75rem;
    color: #888;
    margin: 0.5rem 0 0;
}

@media (max-width: 600px) {
    .container {
        padding: 0.5rem;
    }
    h2 {
        font-size: 1.1rem;
    }
    .controls button {
        font-size: 0.75rem;
        padding: 0.3rem 0.7rem;
    }
}