style.css

html {
	height: 100%;
	padding: 0.8em;
	display: flex;
	background: hsl(220 10% 50%);
}

body {
	--padding: 0.8em 1.2em 2em;

	box-sizing: border-box;
	margin: auto;
	padding: var(--padding);
	border-radius: 0.5em;
	background: hsl(0 0% 100% / 0.9);
	box-shadow: 1px 1px 10px rgb(0 0 0 / 0.5);
	font: var(--font-size-lh) Helvetica Neue, sans-serif;
	text-align: center;
}

body:not(:has(footer)) {
	padding-bottom: 1em;
}

h1 {
	font-size: 130%;
}

h1 a {
	display: block;
}

body img {
	display: block;
	margin: 0 auto;
	height: 4em;
	block-size: 4em;
}

a[href] {
	word-break: break-all;
}

#backend_list {
	list-style-type: none;

	max-width: 80%;
	padding: 0;
	margin: 0.5em auto 2em;

	display: grid;
	gap: 0.5em;
	grid-template-columns: repeat(auto-fit, minmax(4.5em, 1fr));
}

.backend {
	display: flex;
	flex-direction: column;
	gap: 0.2em;
	justify-content: space-between;
}

.backend img {
	display: block;
	margin: 0 auto;
	height: 3em;
	aspect-ratio: 1;
}

#auth {
	max-width: 60ch;
}

footer {
	display: flex;
	flex-direction: column;
	gap: 0.7em;
}

button {
	flex: 1;
	padding: 0.8em 0.5em;
	border: none;
	border-radius: 0.3em;
	font: inherit;
	font-weight: bold;
	text-wrap: balance;
	color: white;
	cursor: pointer;
	box-shadow: 0 0 hsl(0 0% 100% / 0.2) inset;
	transition: 0.4s box-shadow;
}

button:hover {
	box-shadow: 0 1em hsl(0 0% 100% / 0.2) inset;
}

button.yes {
	background: hsl(85 80% 45%);
}

button.no {
	background: hsl(0 80% 45%);
}

@media screen and (min-width: 425px) {
	footer {
		flex-direction: row;
		gap: 1em;
	}
}

@media screen and (min-width: 540px) {
	body {
		--padding: 1em 3em 2em;
		--font-size-lh: 120%/1.2;

		max-width: 85vw;
	}
}

@media screen and (min-width: 685px) {
	body {
		--font-size-lh: 150%/1.5;
	}
}