style.css

@import  url('https://fonts.googleapis.com/css2?family=Nunito&display=swap');

* {
    margin: 0%;
    padding: 0%;
}

body {
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: coral;
}

.calculator {
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: rgb(36, 36, 36);
    border-radius: 20px;
    width: 400px;
    height: 500px;
    box-shadow: 0px 0px 15px 5px black;
}

.ui {
    display: flex;
    border-radius: 20px;
    width: 375px;
    height: 475px;
    flex-direction: column;
}

.display {
    display: flex;
    justify-content: center;
    align-items: center;
    flex: 1;
}

#screen {
    display: flex;
    justify-content: end;
    flex-direction: column;
    background-color: rgba(121, 121, 121, 0.787);
    border-radius: 10px;
    font-size: 25px;
    width: 370px;
    height: 110px;
    color: rgb(0, 166, 0);
    overflow: hidden;
}

.input {
    display: flex;
    justify-content: end;
    align-items: center;
    height: 50px;
    color: rgb(0, 161, 0);
    word-wrap: wrap;
    padding: 5px;
}

.result {
    display: flex;
    justify-content: end;
    align-items: center;
    height: 50px;
    color: white;
    padding: 5px;
}

.num-btn-pad {
    flex: 3;
    border: 2px solid rgb(17, 17, 17);
    border-radius: 10px;
    flex-direction: column;
}

.row {
    display: flex;
    justify-content: space-around;
    align-items: center;
    height: 70px;
    flex-direction: row;
}

button {
    border-radius: 100px;
    width: 60px;
    height: 60px;
    background-color: rgb(66, 66, 66);
    text-decoration: none;
    border: none;
    color: white;
    font-family: 'Nunito', sans-serif;
    font-size: 22px;
    box-shadow: 5px 5px 8px black;
    transition: .2s;
}

button:hover {
    transform: scale(1.1);
    background-color: rgb(202, 202, 202);
    color: rgb(21, 21, 21);
}

.equal-btn {
    width: 150px;
    background-color: indianred;
}

.opp-btn, .clear-btn, .delete-btn {
    background-color: coral;
}