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

body {
    font-family: Arial, sans-serif;
    background-color: #f5f5f5;
    color: #333;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background-color: white;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

h1 {
    text-align: center;
    margin-bottom: 20px;
    color: #2c3e50;
    font-size: 28px;
}

.loading-msg {
    text-align: center;
    padding: 20px;
    color: #3498db;
    font-size: 16px;
    font-weight: bold;
}

.controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    margin-bottom: 20px;
}

.controls label {
    font-weight: bold;
    color: #2c3e50;
    white-space: nowrap;
}

.model-picker {
    display: flex;
    gap: 0;
}

.model-btn {
    padding: 8px 18px;
    font-size: 15px;
    border: 1px solid #ddd;
    background-color: white;
    color: #333;
    cursor: pointer;
    margin-right: -1px; /* collapse borders between buttons */
}

.model-btn:first-child { border-radius: 4px 0 0 4px; }
.model-btn:last-child  { border-radius: 0 4px 4px 0; margin-right: 0; }

.model-btn.active {
    background-color: #2c3e50;
    color: white;
    border-color: #2c3e50;
    z-index: 1;
}

#chart {
    margin: 0 auto;
}

#contact {
    text-align: center;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid #ddd;
    color: #7f8c8d;
    font-size: 13px;
}

#contact a {
    color: #3498db;
    text-decoration: none;
}

#contact a:hover {
    text-decoration: underline;
}

@media (max-width: 768px) {
    .container {
        padding: 15px;
    }

    h1 {
        font-size: 20px;
        margin-bottom: 15px;
    }

    .model-btn {
        flex: 1;
        font-size: 16px;
        padding: 10px;
    }
}