*, *::before, *::after {
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
}

body {
    background: linear-gradient(to left, lightskyblue, rgb(255, 215, 140));
    margin: 0;
    padding: 0;
    max-height: 100vh;
}

.calculator {
    align-content: center;
    display: grid;
    grid-template-columns: repeat(4, 100px);
    grid-template-rows: repeat(6, 100px);
    justify-content: center;
    min-height: 100vh;
}

.calculator > button {
    border: 2px solid rgb(49, 36, 36);
    cursor: pointer;
    font-size: 2rem;
    outline: none;
}

.operand, .decimal {
    background-color: rgb(104, 103, 103);
    transition: 0.2s;
}

.operand:hover,
.decimal:hover {
    background-color: rgb(180, 178, 178);
}

.special {
    background-color: rgb(167, 167, 253);
    transition: 0.2s;
}

.special:hover {
    background-color: rgb(214, 214, 255);
}

.operator {
    background-color: orange;
    transition: 0.2s;
}

.operator:hover {
    background-color: rgb(255, 195, 82);
}

.span-two {
    grid-column: span 2;
}

.output {
    align-items: flex-end;
    background-color: lightgrey;
    border: 5px solid rgb(49, 36, 36);
    display: flex;
    flex-direction: column;
    grid-column: 1 / -1;
    justify-content: space-around;
    overflow: hidden;
    padding: 10px;
}

.output .previous-input {
    opacity: 50%;
    font-size: 1.5rem;
}

.output .current-input {
    font-size: 2.5rem;
}

footer {
    background-color: darkblue;
    cursor: pointer;
    margin-top: auto;
    padding: 10px 0;
    text-align: center;
}

.github-link {
    color: white;
    text-decoration: none;
    transition: all 0.3s;
}

.github-link:hover {
    color: rgb(140, 199, 255);
}