body {
    font-family: sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    background-color: #f4f4f4;
}

.container {
    background-color: #fff;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    text-align: center;
}

.chart-area {
    position: relative;
    display: inline-block; /* To contain the absolute positioned bar */
    margin-top: 20px;
    border: 1px solid #ccc;
}

.chart-area img {
    display: block; /* Remove extra space below image */
    max-width: 100%;
    height: auto;
}

.age-bar {
    position: absolute;
    top: 0;
    left: 0; /* Will be updated by JS */
    width: 6px;
    height: 100%;
    background-color: rgba(220, 53, 69, 0.85); /* Premium semi-transparent red */
    border-radius: 3px;
    cursor: grab;
    z-index: 10;
    box-shadow: 0 0 6px rgba(0, 0, 0, 0.4);
    transition: width 0.1s ease, background-color 0.1s ease, box-shadow 0.1s ease;
}

.age-bar:hover {
    width: 8px;
    background-color: rgba(220, 53, 69, 1.0);
    box-shadow: 0 0 8px rgba(220, 53, 69, 0.6);
}

.controls {
    margin-top: 20px;
}

input[type="number"] {
    padding: 8px;
    margin-left: 10px;
    border: 1px solid #ccc;
    border-radius: 4px;
}