* {
    box-sizing: border-box;
}

html, body {
    margin: 0;
    padding: 0;
}

.container {
    width: 90%;
    height: 90%;
    margin: auto;
}

h1 {
    font-family: "Berkshire Swash", sans-serif;
    text-align: center;
    letter-spacing: 3px;
    font-size: 3em;
    margin: 0.25em;
    color: #c0392b;
}

.calc-body {
    width: 40em;
    height: fit-content;
    margin: 2em auto;
    padding: 0 0 2em 0;
    border: #c0392b solid 2px;
}

.input {
    width: 95%;
    padding: 1em 1em 0.5em;
    margin: auto;
}

input {
    display: block;
    width: 100%;
    margin: auto;
    font-size: 2em;
    font-family: "Berkshire Swash", 'Courier New', Courier, monospace;
    color: #f1c40f;
    background-color: #c0392b;
    border: none;
    border-radius: 10px;
    letter-spacing: 2px;
    padding: 0.5em 0.25em;
    caret-color: transparent;
}

input:focus, input:active {
    outline-color: transparent;
}

.row {
    width: 95%;
    padding: 0.25em 1em 0.25em;
    margin: auto;
}

.cell {
    display: inline-block;
    width: 24.4%;
}

.cell button {
    display: block;
    width: 100%;
    border-radius: 0.25em;
}

.light {
    position: relative;
    background: #d35400;
    padding: 1rem 1rem;
    font-size: 1.6rem;
    border: none;
    color: white;
    cursor: pointer;
    outline: none;
    overflow: hidden;
}

.light span {
    position: relative;
}

.light::before {
    --size: 0;
    content: '';
    position: absolute;
    left: var(--x);
    top: var(--y);
    width: var(--size);
    height: var(--size);
    background: radial-gradient(circle closest-side, #f39c12, transparent);
    transform: translate(-50%, -50%);
    transition: width .3s ease, height .3s ease;
}

.light:hover::before {
    --size: 250px;
}