body {
    background-color: #1a1a1a;
    color: white;
    font-family: 'Arial', sans-serif;
    margin: 0;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

h1 {
    margin-bottom: 20px;
    color: #aaa;
}

.controls {
    margin-bottom: 20px;
    background: #2a2a2a;
    padding: 10px;
    border-radius: 10px;
}

button {
    background: transparent;
    border: 1px solid #4CAF50;
    color: #4CAF50;
    padding: 8px 16px;
    margin: 0 5px;
    cursor: pointer;
    border-radius: 5px;
    font-size: 1rem;
    transition: 0.3s;
}

button:hover, button.active {
    background: #4CAF50;
    color: white;
}

.chart-container {
    position: relative;
    height: 60vh;
    width: 90vw;
    max-width: 1000px;
    background: #222;
    padding: 20px;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
}

.back-link {
    margin-top: 20px;
    color: #888;
    text-decoration: none;
}

.back-link:hover {
    text-decoration: underline;
    color: white;
}