style.css

@import url('https://fonts.googleapis.com/css2?family=Mulish:wght@300&display=swap');

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: 'Mulish', sans-serif;
    background-color: #3faafc;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    overflow: hidden;
}


.calculator {
    width: 23rem;
    background-color: #fff;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 2px 2px 20px 5px rgba(0,0,0,0.2);

}

.answer-section {
   align-self: flex-end;
   display: flex;
   flex-direction: column;
   justify-content: space-between;
   height: 7rem;
   max-height: 11rem;
   width: 100%;
}

.answer-section .currentText {
    color: #12567c;
    margin-top: 0;
    text-align: right;
    font-size: 40px;
    height: 4rem;
    word-wrap: break-word;
    word-break: break-all;
}

.answer-section .prevText {
    color: #12567c;
    font-size: 1.5rem;
    height: 1.2rem;
    width: 100%;
    text-align: right;
    margin-top: 0;
}

.line {
    width: 100%;
    height: 1px;
    background-color: rgba(121, 125, 128,0.3);
    margin-bottom: 1rem;
}

.controls {
    display: grid;
    grid-template-columns: repeat(4, 4rem);
    grid-auto-rows: 4rem;
    grid-gap: 0.9rem;
}

button {
    cursor: pointer;
    font-size: 1.2rem;
    border: none;
    border-radius: 5px;
    background-color: #f5fafa;
    color: #797d80;
    box-shadow: 0 1px 4px rgba(0,0,0,0.1);
    transition: all 0.2s ease;
    outline: none;
}

button:active {
    transform: scale(0.97);
    background-color: rgba(63, 170, 252,0.3);
}

#zero {
    grid-column: span 2;
}

#clear,
#backspace,
#percent,
#division,
#multiply,#minus,#plus,#equals {
    background-color: #d9eeff;
    color: #71b2e4;
}