style.css

@import url('https://fonts.googleapis.com/css2?family=Oswald:wght@200..700&family=Roboto+Slab:wght@100..900&display=swap');

* {
    margin: 0%;
    padding: 0%;
    box-sizing: border-box;
    font-family: 'poppins', sans-serif;

}

body {
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(45deg, #4d3737, #da1515);
}

.calculator {
    border: 1px solid#eee7e7;
    padding: 20px;
    border-radius: 15px;
    background-color: transparent;
    /* background-color: #0dad22; */
    box-shadow: 0px 3px 15px rgba(10, 20, 20, 0.85);

}

input {
    width: 320px;
    border: 1px solid #eee7e7;
    border-radius: 15px;
    padding: 24px;
    margin: 10px;
    box-shadow: 8px 8px 8px rgba(0, 0, 0, 0.4);
    background: transparent;
    box-shadow: 0px 3px 15px rgbs(84, 84, 84, 0.1);
    font-size: 40px;
    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(0, 0, 0, 0.7);
    cursor:pointer;
}

.equalBtn {
    background: #ff0000;
}

.operator {
    color: #48ff00;
    font-size: 20px;
    font-weight:bold;
}