*{
    box-sizing:border-box;
}

body{
    margin:0;
    padding:15px;
    text-align:center;
    font-family:Verdana, sans-serif;
    background:#0f172a;
    color:#e2e8f0;
}

h4{
    margin-bottom:25px;
    font-size:24px;
}

.box1{
    background:#1e293b;
    padding:25px;
    border-radius:16px;
    width:90%;
    max-width:420px;
    margin:auto;
    box-shadow:0 10px 25px rgba(0,0,0,.3);
}

.box{
    width:130px;
    height:130px;
    margin:15px auto;
    border-radius:12px;
    border:3px solid #334155;
}

.slider-row{
    margin:18px 0;
    text-align:left;
}

.slider-row label{
    display:block;
    margin-bottom:8px;
    font-weight:bold;
}

input[type=range]{
    width:100%;
    cursor:pointer;
}

/* h3{
    margin-top:20px;
    font-size:23px;
} */

.on{
    padding: 12px 20px;
    font-size: 16px;
    background-color: #333;
    color: white;
    border: none;
    border-radius: 15px;

    box-shadow: 0 5px #eee;
    cursor: pointer;
}

.on:active {
    transform: translateY(3px);
    box-shadow: 0 2px #eee;
}

@media(max-width:500px){

    body{
        padding:12px;
    }

    h2{
        font-size:26px;
    }

    .box1{
        width:100%;
        padding:18px;
    }

    .box{
        width:100px;
        height:100px;
    }

    h3{
        font-size:20px;
    }
}