body, html {
    margin: 0;
    padding: 0;
    height: 100%;
    font-family: Arial, sans-serif;
    background-color: #333;
}

#map {
    height: 100vh;
    width: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 1; /* behind UI */
}

#ui-container {
    position: absolute;
    top: 20px;
    left: 50%;
    transform: translateX(-50%);
    width: 80%;
    max-width: 800px;
    background: rgba(255, 255, 255, 0.9);
    padding: 15px 30px;
    border-radius: 10px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    z-index: 1000; /* above map */
    text-align: center;
}

.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
}

.header h1 {
    margin: 0;
    font-size: 1.5em;
    color: #333;
}

.year-display {
    font-size: 1.2em;
    font-weight: bold;
    color: #0056b3;
}

.controls {
    display: flex;
    align-items: center;
    gap: 15px;
}

#play-btn {
    padding: 8px 15px;
    background-color: #0056b3;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-weight: bold;
    font-size: 1em;
}

#play-btn:hover {
    background-color: #003d82;
}

#time-slider {
    flex-grow: 1;
    -webkit-appearance: none;
    appearance: none;
    height: 10px;
    background: #ddd;
    outline: none;
    border-radius: 5px;
}

#time-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    background: #0056b3;
    cursor: pointer;
    border-radius: 50%;
}

#time-slider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    background: #0056b3;
    cursor: pointer;
    border-radius: 50%;
}