style.css

@import url('https://fonts.googleapis.com/css2?family=Roboto&display=swap');
*{
    margin: 0;
    padding: 0;
    font-family: 'Roboto', sans-serif;
    box-sizing: border-box;
}
body{
    width: 100%;
    height: 100vh;
    background: linear-gradient(45deg,#36454F, #301934);
    display: flex;
    justify-content: center;
    align-items: center;
}
.calculater{
    border: 1px solid #36454F;
    border-radius: 12px;
    padding: 20px;
    box-shadow: rgba(87, 87, 87, 0.35) 0px 5px 15px;
}
input{
    width: 320px;
    padding: 25px;
    margin: 15px;
    font-size: 35px;
    background: transparent;
    border: none;
    text-align: right;
    cursor: pointer;
    color: #ffffff;
}
input::placeholder{
    color: #ffffff;
}
button{
    border: none;
    width: 60px;
    height: 60px;
    margin: 10px;
    border-radius: 50px;
    background: transparent;
    color: #ffffff;
    font-size: 20px;
    box-shadow: -8px -8px 15px rgba(255, 255, 255, 0.1);
    cursor: pointer;
}
.equalBtn{
    background: rgb(141, 141, 14);
}
.operator{
    color: rgb(174, 255, 0);
}