style.css

  @import url('https://fonts.googleapis.com/css2?family=Dosis:wght@200;800&family=Kanit:wght@500&family=Montserrat:wght@100;400;900&family=Roboto:ital,wght@0,400;1,300;1,700&family=Tilt+Neon&family=Ubuntu&display=swap');

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'dosis' sans-serif;
     
}
body{
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;/* make content horizontaly center*/
    align-items: center;/* make item verticlly center*/
    background: linear-gradient(50deg,#921235, #732154);
}
.cal{
    border: 1px solid white;
    padding: 20px;
    border-radius: 16px;
    background: transparent;
    box-shadow: 0px 3px 10px;
}
input{
    width: 100%;
    border: none;
    padding: 24px;
    margin: 10px;
    background: transparent;
    box-shadow: 0px 3px 15px;
    font-size: 40px;
    text-align: right;
    cursor: pointer;  
    color: white;
}
button{
    border: none;
    width: 120px;
    height: 60px;
    margin: 10px;
    border-radius: 10%;
    background: transparent;
    color: white;
    font-size: 20px;
    box-shadow: -8px -8px 15px rgba(255, 255, 255, 0.1);
    cursor: pointer; 
}
.eq{
background-color: orange;
}
.op{
background-color: #6dee0a;
}