style.css

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.container {
    height: 100vh;
    width: 100%;
    background-color: rgba(255, 255, 0, 0.585);
    display: flex;
    justify-content: center;
    align-items: center;
}

.main-container {
    background-color: rgb(244, 122, 88);
    box-shadow: 0px 5px 10px rgba(0, 0, 0, 0.5);
    display: grid;
    place-content: center;
    gap: 3rem;
    /* height: 40vh; */
    width: 40vw;
    border: 2px solid black;
    padding: 2rem;
}

.heading {
    font-size: 1.5rem;
}

.calculation {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
}

input , select {
    width: 20%;
    height: 1.5rem;
    font-style: italic;
    font-size: 1rem;
}

input {
    border: none;
    padding: 10px;
    border-radius: 5px;
    font-size: 2rem;
    height: 2vw;
    width: 7vw;
}

select {
    height: 2vw;
    width: 7vw;
    font-size: 1rem;
    border: none;
    border-radius: 5px;
}

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

.submit-btn {
    font-size: 1rem;
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 5px;
    background-color: rgb(42, 95, 211);
    color: white;
    font-weight: bolder;
    box-shadow: 0px 5px 15px rgba(114, 57, 41,0.7);
    transition: all 0.1s ease-in-out;
}

.submit-btn:hover{
    transform: scale(1.05);
    background-color: rgb(72, 112, 200);
    transition: all 0.1s ease-in-out;
}

.result {
    text-align: center;
    font-size: 2rem;
    font-weight: 600;
}