style.css

/* General styles */
*,
*::before,
*::after {
    box-sizing: border-box;
    padding: 0;
    margin: 0;
}

html {
    overflow-y: scroll;
    overflow-x: hidden; 
}
body {
    min-height: 100vh;
    height: 100vh;
    font-family: 'Montserrat', sans-serif;
    background-color: #F9FBFC;
    color:rgb(62, 76, 117);
    display: flex;
    flex-direction: column;
    justify-content: space-around;
    margin: 0 auto;
    position: relative;
    text-align: center;
}

.calculator {
    padding: 1rem;
    margin: 0 auto;
    background-color: rgba(62, 76, 117, 0.4);
    width: 28rem;
    border: 2px solid rgb(62, 76, 117);
    border-radius: 6px;
}

.numbers-container {
    width: 100%;
}

.display {
    background-color: #F9FBFC;
    padding: 0.5rem;
    height: 8rem;
    max-width: 100%;
    margin-bottom: 1rem;
    border-radius: 3px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    overflow-wrap: break-word;
    text-align: right;
    font-size: 2.5rem;
    font-weight: 500;
}

.big-number {
    font-size: 2rem;
}

.delete-clear {
    display: flex;
    justify-content: space-evenly; 
    align-items: center; 
    width: 100%;
    margin-bottom: 1rem;
}
.delete,.clear {
    width: 45%;
}
.delete {
    background-color: #0b95e6;
}

.clear {
    background-color: #ec5418;
}

.number-row {
    margin-bottom: 1rem;
    display: flex;
    justify-content: space-evenly; 
    align-items: center; 
}

button {
    min-width: 90px;
    font-size: 1rem;
    font-weight: 400;
    border: none;
    outline: none;
    background-color: rgb(62, 76, 117);
    color: rgb(255, 255, 255);
    padding: 1rem 1rem;
    border-radius: 3px;
}

button:hover {
    border: none;
    cursor: pointer;
    opacity: 0.8;
}

/* Footer */
.attribution {
    text-align: center;
    width: 100%;
    padding-bottom: 0.3rem;
    font-size: 0.7rem;
    position: absolute;
    bottom: 0;
    left: 0;
    z-index: 999;
}

.attribution a {
    margin-left: 0.3rem;
}