styles.css

/* https://fonts.google.com/share?selection.family=Atkinson+Hyperlegible|Courier+Prime|Cousine|Geologica|Merriweather|Ubuntu+Mono */
@import url('https://fonts.googleapis.com/css2?family=Atkinson+Hyperlegible&family=Courier+Prime&family=Cousine&family=Geologica&family=Merriweather&family=Ubuntu+Mono&display=swap');

* {
	box-sizing: border-box;
}

/*
font-family: 'Atkinson Hyperlegible', sans-serif;
font-family: 'Courier Prime', monospace;
font-family: 'Cousine', monospace;
font-family: 'Geologica', sans-serif;
font-family: 'Merriweather', serif;
font-family: 'Ubuntu Mono', monospace;
*/

:root {
	font-size: 16px;
	--mainFont: 'Cousine', monospace;
	--mainFontSize: 20px;
}

@media (max-width: 750px) {
	:root {
		font-size: 14px;
	}
}

@media (max-width: 360px) {
	:root {
		font-size: 12px;
	}
}

html, body {
	display: block;
	width: 100%;
	height: 100%;
	margin: 0;
	padding: 0;
}

main {
	display: block;
	margin: 0 auto;
	padding-top: 2rem;

	max-width: 750px;
	height: 90%;
}

textarea {
	display: block;
	width: 100%;
	height: 100%;
	padding: 0 0.5rem;

	color: #333;
	tab-size: 4;
	font-size: var(--mainFontSize);
	font-family: var(--mainFont), monospace;

	word-break: normal;
	overflow-wrap: break-word;
	white-space: pre-wrap;

	resize: none;
	outline: none;
	box-shadow: none;
	border: none;
}

textarea::-webkit-scrollbar {
	display: none; /* Chrome, Safari and Opera */
}

textarea {
	-ms-overflow-style: none;  /* IE and Edge */
	scrollbar-width: none;  /* Firefox */
}

footer {
	display: block;
	width: 100%;
	height: 10%;

	margin: 0 auto;
	padding: 1.3rem 0 0 0;

	color: #555;
	font-family: 'Cousine', monospace;
	font-size: 0.9rem;

	line-height: 1.5;
	text-align: center;
}

footer div.footerControls, footer span.separator {
	user-select: none;
}

footer span.separator {
	padding: 0 0.5rem;
}

select#fontSelector {
	font-family: 'Cousine', monospace;
	padding: 0.1rem 0.2rem;
	border: 1px solid #CCC;
	max-width: 8rem;
	border-right: none;
}

input#fontSize {
	font-family: 'Cousine', monospace;
	padding: 0.1rem 0 0.1rem 0.3rem;
	border: 1px solid #CCC;
	max-width: 4rem;
}