calci.css

* {
    background-color: #fefff3;
    margin: 15px;
    padding: 0%;
    box-sizing: border-box;
    outline: none;
    font-family: sans-serif;
}

.container {
    height: 500px;
    justify-content: center;
    align-items: center;
    display: flex;
}

.calculator {
    background-color: rgb(0, 249, 255);
    padding: 15px;
    border-radius: 12px;
    box-shadow: inset 3px 3px 7px rgba(0, 0, 0, 0.23),
        inset -3px -3px 5px rgba(0, 0, 0, 0.289);
    display: grid;
    grid-template-columns: repeat(4, 75px);
}

input {
    grid-column: span 4;
    height: 78px;
    width: 282px;
    background-color: rgb(239, 248, 255);
    box-shadow: inset -5px -5px 3px rgba(0, 0, 0, 0.174),
        inset 5px 5px 3px rgba(0, 0, 0, 0.173);
    border: none;
    border-radius: 7px;
    color: black;
    font-size: 55px;
    text-align: end;
    margin: auto;
    margin-top: 4opx;
    margin-bottom: 20px;
    padding: 20px;
}

button {
    height: 50px;
    width: 60px;
    background-color: rgba(255, 255, 255, 0.971);
    box-shadow: -2px -2px 5px rgba(0, 0, 0, 0.442),
        2px 2px 5px rgba(13, 13, 13, 0.474);
    margin: 8px;
    border-radius: 5px;
    border: none;
    font-size: 30px;
    cursor: pointer;
}

button:hover {
    height: 50px;
    width: 60px;
    color: rgb(255, 255, 255);
    background-color: rgb(1, 2, 0);
    box-shadow: -2px -2px 5px rgba(0, 0, 0, 0.442),
        2px 2px 5px rgba(13, 13, 13, 0.474);
    margin: 8px;
    border-radius: 5px;
    border: none;
    font-size: 30px;

}

.btn2 {
    height: 50px;
    width: 137px;
    background-color: rgb(252, 255, 244);
    box-shadow: -2px -2px 5px rgba(0, 0, 0, 0.581),
        2px 2px 5px rgba(13, 13, 13, 0.585);
    margin: 8px;
    border-radius: 5px;
    border: none;

}

.btn2:hover {
    color: rgb(1, 255, 255);
    background-color: rgb(0, 0, 0);
    height: 50px;
    width: 137px;
    border-radius: 5px;
}

h1 {
    color: rgb(0, 0, 0);
    text-align: center;
    font-size: 50px;
    border-radius: 5px;
}
h6 {
    color: rgb(137, 137, 137);
    text-align: center;
    font-size: 30px;
    border-radius: 5px;
}