:root {
    /*
    the block angle represent the vertex position of the triangle,
    it has four values:
    0 - the vertex at top-left
    90 - the vertex at top-right
    180 - the vertex at bottom-right
    270 - the vertex at bottom-left
    */
    --block-angle-1: 0;
    --block-angle-2: 0;
    --block-angle-3: 0;
    --block-angle-4: 0;
}

body {
    margin: 0 auto;
    height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    font-size: 0.75em;
    font-family: sans-serif;
    background: linear-gradient(to right bottom, lightcyan, lightblue);
}

h1 {
    font-weight: normal;
    margin: 2em;
    letter-spacing: 0.1em;
}

main {
    display: flex;
    justify-content: space-between;
    width: 65em;
}

.sample {
    width: 20em;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.sample > .tile {
    margin-bottom: 4em;
}

.sample > .tile .block {
    cursor: pointer;
}

.sample .pattern-list {
    font-size: 0.2em;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 5em;
}

.sample .pattern-list .tile {
    cursor: pointer;
}

/* the color of default pattern is a lighter color */
.sample .pattern-list .tile:first-child .block {
    color: lightgrey;
}

.production {
    width: 40em;
}

.production .floor {
    --count-of-per-side: 2;
    display: grid;
    grid-template-columns: repeat(var(--count-of-per-side), 1fr);
    font-size: calc(2em / var(--count-of-per-side));
}

.production .grid-list {
    display: flex;
    justify-content: space-around;
    margin-top: 2em;
}

.production .grid-list button {
    font-size: 1.5em;
    width: 6em;
    letter-spacing: 0.4em;
    cursor: pointer;
}

.tile {
    width: 20em;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
}

.tile .block {
    width: 10em;
    height: 10em;
    border: 1px solid grey;
    box-sizing: border-box;
    color: dimgray;
    position: relative;
    transition: 0.2s;
}

.tile .block::before {
    content: '';
    position: absolute;
    border-width: calc(5em - 1px);
    border-style: solid;
    border-color: currentColor transparent transparent currentColor;
}

.tile .block:nth-child(1) {transform: rotate(calc(var(--block-angle-1) * 1deg));}
.tile .block:nth-child(2) {transform: rotate(calc(var(--block-angle-2) * 1deg));}
.tile .block:nth-child(3) {transform: rotate(calc(var(--block-angle-3) * 1deg));}
.tile .block:nth-child(4) {transform: rotate(calc(var(--block-angle-4) * 1deg));}

.sample > .tile,
.production .floor {
    box-shadow: 
        0 0 0 9px lightcyan,
        0 0 0 10px grey;
}