Fix bugs in pdf exporter

_sass/_main.scss

@@ -159,6 +159,10 @@ footer a:hover {
 		font-size: 11pt;
 	}
 
+	footer {
+		display: none;
+	}
+
 	#container {
 		max-width: none;
 		margin: 0;

utils/convert_to_pdf.js

@@ -33,7 +33,7 @@ var links = {{ site.data.links_en | jsonify }};
 			// page.pdf() is currently supported only in headless mode.
 			// @see https://bugs.chromium.org/p/chromium/issues/detail?id=753118
 			const margin = "0.2in"
-			const file_seg = link.num ? link.num.pad() : ("0_" + link.title.replace(".", "_"))
+			const file_seg = link.num ? link.num.pad() : ("00_" + link.title.replace(".", "_"))
 			await page.pdf({
 				path: "tmp/page_" + file_seg + ".pdf",
 				format: "A5",