style.css

@import url('https://fonts.googleapis.com/css2?family=Open+Sans:ital,wght@0,300;0,400;0,500;0,600;0,700;0,800;1,300;1,400;1,500;1,600;1,700;1,800&display=swap');
@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;0,800;1,100;1,200;1,300;1,400;1,500;1,600;1,700;1,800&display=swap');

:root {
	--fonts: "Open Sans", Helvetica, system-ui, sans-serif;
	--mono-fonts: "JetBrains Mono", "Menlo", "Courier", monospace;
	--text-color: #bacbde;
	--background-color: #121a21;
	--button-bg-color: #3f6187;
	--txt-background-color: #273747;
	--border-color: #283848;
	--link-hover-color: #7b8da3;
}

* {
	font-family: var(--fonts);
	font-size: 1em;
	text-align: center;
	color: var(--text-color);
}

html {
	color-scheme: dark;
}

body {
	background-color: var(--background-color);
}

main {
	display: flex;
	flex-direction: column;
	align-items: center;
	width: min(128ch, calc(100% - 4rem));
	margin-inline: auto;
	padding: 1.5rem;
}

footer {
	background-color: #31495e7f;
	padding: 1.5rem;
	font-size: 0.875em;
}

strong {
	font-weight: 500;
}

button {
	background-color: var(--button-bg-color);
	border: none;
	font-size: 0.875em;
	border-radius: 1em 1em;
	padding: 0.625em 1.25em;
	cursor: pointer;
	margin-top: 1rem;
	margin-bottom: 1rem;
}

h1, h2, h3 {
	text-wrap: balance;
}

a {
	color: var(--text-color);
	text-align: center;
	text-decoration: underline;
	transition: color 250ms ease-in-out;
}

a:hover {
	color: var(--link-hover-color);
	text-decoration: underline;
}

mark {
	background-color: #6c91b27f;
}

h1 {
	font-weight: 800;
	font-size: 2em;
}

h2 {
	font-weight: 700;
	font-size: 1.5625em;
}

h3 {
	font-weight: 600;
	font-size: 1.325em;
}

textarea {
	width: 24em;
	height: 21em;
	font-family: var(--mono-fonts);
	background-color: var(--txt-background-color);
	border-color: var(--border-color);
	border-width: 0.15em;
	margin-bottom: 0.5rem;
	margin-top: 0.5rem;
	font-weight: 400;
	font-size: 0.85em;
	text-align: left;
	border-radius: 1em 1em;
}

p {
	font-weight: 300;
	text-align: justify;
}

pre {
	border-color: var(--border-color);
	background-color: var(--txt-background-color);
	border-width: 0.15em;
	border-radius: 1em 1em;
	padding: 1em;
	font-size: 0.85em;
	font-family: var(--mono-fonts);
	text-align: left;
}

::selection {
	background-color: #31495e7f;
}