https://www.circuloromanico.com/admin/textsizer.js

1//Specify affected tags. Add or remove from list:
2var tgs = new Array( 'span','a','div','td','tr');
3
4//Specify spectrum of different font sizes:
5var szs = new Array('xx-small','x-small','small','medium','large');
6var startSz = 1;
7
8function ts( trgt,inc ) {
9	if (!document.getElementById) return
10	var d = document,cEl = null,sz = startSz,i,j,cTags;
11	
12	sz += inc;
13	if ( sz < 0 ) sz = 0;
14	if ( sz > 4 ) sz = 4;
15	startSz = sz;
16		
17	if ( !( cEl = d.getElementById( trgt ) ) ) cEl = d.getElementsByTagName( trgt )[ 0 ];
18
19	cEl.style.fontSize = szs[ sz ];
20
21	for ( i = 0 ; i < tgs.length ; i++ ) {
22		cTags = cEl.getElementsByTagName( tgs[ i ] );
23		for ( j = 0 ; j < cTags.length ; j++ ) 
24		cTags[ j ].style.fontSize = szs[ sz ];
25	}
26}