.btn {
    border-radius: 5px;
    background-color: rgba(0, 0, 0, 0);
    border-width: 3px;
    color : whitesmoke;
    border-color: whitesmoke;
}

#board {
    margin: 0;
    padding: 0;
    width: 40%;
    height: 80%;
    position: relative;
}

#popup {
    background-color: rgba(112, 110, 110, 0.646);
    height: auto;
    border-radius: 5px;
    text-align: center;
    box-shadow: 2px;
    font-size : 16px;
    margin-left: 15%;
    margin-right: 15%;
}

/* Slider controls */
.slider {
    -webkit-appearance: none;
    height: 10px;
    background: none;
    border-radius: 4px;
    outline: white solid 2px;
    -webkit-transition: .2s;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 15px;
    height: 15px;
    border-radius: 50%;
    background: #ffffff;
    cursor: pointer;
}