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

html {
    height: 100%;
}

body {
    height: 100%;
    width: 100%;
}

.content {
    background-image: url(../image/background.jpg);
    background-repeat: repeat-y;
    background-size: cover;
    width: 100%;
    height: 100%;
}

.block-keys {
    position: relative;
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;
    width: 95%;
    align-items: center;
    justify-content: center;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
}

.keys {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    width: 80px;
    height: 80px;
    border: 2px solid rgb(255, 0, 0);
    margin: 18px;
    transition: all 0.08s ease;
    background-color: rgb(255, 48, 48, 0.1);
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
    color: #145eff;
}

.keys:hover {
    cursor: pointer;
}

kbd {
    display: block;
    font-size: 26px;
    font-weight: bolder;
    color: red;
}

span {
    padding-top: 10%;
    font-size: 16px;
}

.on-play {
    transform: scale(1.2);
    color: yellow;
    background-color: rgb(255, 48, 48, 0.8);
    box-shadow: 0.5px 0.5px 2px rgb(247, 80, 42),
                -0.5px 0.5px 2px rgb(247, 80, 42);
}