index.css

@import url('https://fonts.googleapis.com/css?family=Poppins:200,300,400,500,600,700,800,900&display=swap');
*
{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
}
body
{
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: #161623;
}
body::before
{
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(#e91e63,#ffc107);
    clip-path: circle(23% at 30% 20%);
}
body::after
{
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(#2196f3,#e91e63);
    clip-path: circle(20% at 70% 90%);
}

.container{
    text-align: center;
    z-index: 10;
    background: rgba(255,255,255,0.05);
    border-radius: 6px;
    overflow: hidden;
    backdrop-filter: blur(15px);
    border-top: 1px solid rgba(255,255,255,0.2);
    border-left: 1px solid rgba(255,255,255,0.2);
    box-shadow: 5px 5px 30px rgba(255,255,255,0.2);
}

.heading{
color: whitesmoke;
font-family: 'Courier New', Courier, monospace;

}

.calculator{
    display: grid;
    position: relative;
    align-items: stretch;
    width: 380px;
    height: 530px;
    margin: 30px;
    background: transparent;
    overflow: hidden;
   

}
table{
    margin: auto;
}
input{
    grid-column: span 4;
    height: 100px;
    width: 395px;
    font-size: 34px;
    font-weight: 100;
    background: transparent;
    color: whitesmoke;
    border: none;
    
    padding: 10px;
    outline: none;
    border-bottom: 1px solid rgba(255,255,255,0.05);
    border-right: 1px solid rgba(255,255,255,0.05);
}
.btn{
    display: grid;
    place-items: center;
    height: 66px;
    width: 90px;
    font-weight: 300;
    cursor: pointer;
    font-size: 20px;
    user-select: none;
    color: white;
    border-radius: 0px;
    grid-column: span;
    border: none;
    background: transparent;
    border-bottom: 1px solid rgba(255,255,255,0.05);
    border-right: 1px solid rgba(255,255,255,0.05);
    margin: 1px;
    transition: 0.5s;
}

.btn:hover{
    transition: 0.2s;
    font-size: 23px;
    background: rgba(255,255,255,.3);
    box-shadow: 0 0 10px #fff, 0 0 40px #f0f8ff, 0 0 80px #f0ffff;
    /* text-shadow: 0 0 10px #fff, 0 0 40px #fff, 0 0 80px #fff; */
}

.btn:active{
    box-shadow: none;
}