function getElementsByClass(searchClass, node, tag) { 
var classElements = new Array(); 
if ( node == null ) 
node = document; 
if ( tag == null ) 
tag = '*'; 
var els = node.getElementsByTagName(tag); 
var elsLen = els.length; 
var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)"); 
for (i = 0, j = 0; i < elsLen; i++) { 
if ( pattern.test(els[i].className) ) { 
classElements[j] = els[i]; 
j++; 
} 
} 
return classElements; 
} 

        // Xavier Borderie
function tailleFonte(classe, taille) { 
cibles = getElementsByClass(classe); 
for (i = 0; i < cibles.length; i++) { 
        cibles[i].style.fontSize = taille; 
        } 
    }