body {
    font-family: Arial, sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    background-color: #2c3e50;
    color: white;
    padding: 20px;
}

#game-stage {
    width: 400px;
    height: 300px;
    border: 5px solid #3498db;
    overflow: hidden;
    position: relative;
    margin: 20px 0;
    display: flex;
    justify-content: center;
    align-items: center;
}

#target-container {
    /* This element is the filter application point */
    width: 100%;
    height: 100%;
    transition: filter 0.1s linear; /* Smooth visual feedback */
    display: flex;
    justify-content: center;
    align-items: center;
}

#hidden-image {
    max-width: 100%;
    max-height: 100%;
    display: block;
}

/* --- Controls Styling --- */
#controls {
    width: 400px;
    padding: 20px;
    background-color: #34495e;
    border-radius: 5px;
}

.control-group {
    display: flex;
    align-items: center;
    margin-bottom: 10px;
}

.control-group label {
    flex: 2;
    margin-right: 10px;
}

.control-group input[type="range"] {
    flex: 4;
}

.control-group span {
    flex: 1;
    text-align: right;
}

#check-button {
    padding: 10px 20px;
    background-color: #2ecc71;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    margin-top: 15px;
}