styles.css

body {
    text-align: center;
    background-color: #008080;
}
.card {
    
    border: 1px solid #ddd;
    border-radius: 4px;
    box-shadow: 2px 10px 10px 2px #808080;
    background-color: #c0c0c0;
}

h1 {
    font-family: Monoton;
    font-size: 70px;
    margin: 0.2em;
}

h2 {
    margin: 1em 0 0.25em;
    font-family: "28 days later";
    color: #dc1432;
}

h2:first-of-type {
    margin-top: 0.5em;
}

table,
tr,
td {
    border: 1px solid black;
}

table {
    border-collapse: collapse;
    margin: 0 auto;
}

tr {
    height: 20px;
}

td {
    width: 20px;
}

input[type=number] {
    width: 6em;
}

.error {
    border-radius: 0;
    content:"";
    position: absolute;
    top: 0; left: 0;
    width: inherit; height: inherit;
    border-radius: 999px;
    box-shadow: inset 30px 0 0 rgba(226, 82, 88, 0.4),
    inset 0 30px 0 rgba(255, 93, 84, 0.97),
    inset -30px 0 0 rgba(255, 135, 88, 0.94),
    inset 0 -30px 0 rgba(245, 105, 145, 0.4);
    animation: shadowsdancing 4s infinite;
}