Some "user styles" overrides I use to make Github Gists more printable. Well, PDF-izable.

gist-printable.css

@media print {
	
	div.js-header-wrapper,
	.pagehead-actions,
	.pagehead .note a,
	.pagehead div.d-flex.flex-md-row,
	.file-actions,
	.js-discussion
	{ display: none !important; }
	
	.file { border-width: 0; }
	
	.p-5 { border: 0; padding-left: 0 !important; padding-right: 0 !important; padding-top: 16px !important; }
	
	.file-header { background: transparent; }
	
	.markdown-body table { width: 100% !important; display: table; }
	.markdown-body thead,
	.markdown-body tbody,
	.markdown-body tr,
	.markdown-body th,
	.markdown-body td
	{ width: auto; page-break-inside: avoid; }
	
	.markdown-body pre {
		padding: 0 !important;
	}
	
	.markdown-body blockquote { color: #444; }
	
	.markdown-body h3 { margin-top: 0; }
	h1, h2, h3, h4, h5, h6 { page-break-after: avoid; break-after: avoid; }
	h1 + *, h2 + *, h3 + *, h4 + *, h5 + *, h6 + * { page-break-before: avoid; break-before: avoid; }
	
	.markdown-body a { color: black; font-weight: bold; }
	.markdown-body a:not([href^="#"])::after {
		display: inline;
		content: ' (' attr(href) ')';
		font-weight: normal;
	}
	
}