style.css

:root {
    --orange: #f1a33b;
    --gray: #a5a5a5;
    --black: #333333;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    flex-direction: column;
    font-size: em;
    font-family: 'Inter', sans-serif;
    font-weight: 700;
    background-color: #84846d;
}

.calculator {
    border: 1px solid black;
    padding: 1em;
    display: flex;
    flex-direction: column;
    align-items: center;
    border-radius: 30px;
    color: #fff;
    background-color: #000;
}

.calculator__body {
    display: flex;
    justify-content: space-around;
}

.calculator__display {
    border: 1px solid black;
    height: 1em;
    text-align: right;
    align-self: stretch;
    font-size: 2.5em;
    margin: 2.5em 0.4em 0.4em 0.4em;
}

.calculator__buttons {
    display: flex;
    flex-direction: column;
}

.numbers__list {
    display: flex;
    flex-direction: column;
}

.list__line {
    display: flex;
    justify-content: space-around;
}

.line__number {
    border: 1px solid black;
    margin: 0.2em;
    cursor: pointer;
    background-color: var(--black);
}

.operations__list {
    display: flex;
    flex-direction: column;
}

.list__operacao {
    margin-bottom: 0.4em;
    margin: 0 0.2em 0.4em 0.2em;
    cursor: pointer;
    background-color: var(--orange);
    transition: 0.5s;
}

.list__operacao_selection {
    background-color: #fff;
    color: var(--orange);
    transition: 0.5s;
}

.list__operacao:first-child {
    margin-top: 0.2em;
}

.line__number,
.list__operacao {
    width: 1em;
    height: 1em;
    text-align: center;
    border-radius: 352px;
    padding: 1em;
    border: none;
    font-size: 1.5em;
}

.options {
    background-color: var(--gray);
}

.zero {
    flex-grow: 2;
}