How to edit the CSS of an iFrame?

I've just done with jquery using a proxy, now I just work with the css and script to run the tabs, but that's what I leave with you :

jquery:

$('#divframe').load(
    'http://www.corsproxy.com/' +
    'www.cptec.inpe.br/widget/widget.php?p=3819&w=h&c=474647&f=ffffff .tabtop',  function() {
         $('#divframe').html( $('#divframe').html().replace(new RegExp('src="', 'g'),'src="http://www.cptec.inpe.br/widget/'));});

HTML:

<divid="divframe"></div>

jsfiddle: link

EDIT: jsfiddle with the tabs script running: link

Alternative with proper proxy in PHP:

proxy.php (with only this content, and nothing else)

<?php
$cache_file = 'proxy_cache.html'; // nome do arquivo para salvar cache

if (!@file_exists($cache_file) || (time() - @filemtime($cache_file) > (60 * 60 * 6))) { // verificar se o cache expirou e fazer uma nova requisição ao cptec.inpe.br
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, "http://www.cptec.inpe.br/widget/widget.php?p=3819&amp;w=h&amp;c=474647&amp;f=ffffff");
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $retorno = str_replace('src="','src="http://www.cptec.inpe.br/widget/',curl_exec($ch));//adicionaroendereçoabsolutoatodosossrccurl_close($ch);file_put_contents($cache_file,$retorno);//salvarconteudonoarquivodecache}else{//cachenãoexpirouabriroconteudodoarquivosemnovarequisiçãoaocptec.inpe.br$retorno=file_get_contents($cache_file);}echo$retorno;//imprimiroconteudo?>

  

Thecontentbelowmustbeinanotherfile,alongwithcssand  everythingelse...exfile: test.html

jquery:

$('#divframe').load(
    'proxy.php .tabtop',  function() {
         $('#divframe .tab_content').hide();
         $('#divframe .tabs li:first').addClass('active');
         $('#divframe .tab_content:first').show();
         $('#divframe .tabs li').click(function(){
             $('#divframe .tabs li').removeClass('active');
             $(this).addClass('active');
             $('#divframe .tab_content').hide();
             $($(this).children('a').attr('href')).show();
         });
    });

HTML:

<div id="divframe"></div>

By definition, iframe allows you to open an external document, whether it is on the same server or in others. Some javascript solutions can help you do what you want, but only if it's a document on the same server.

So in principle the answer is no.

But, you can create a copy of the external page on your server using PHP:

file_get_contents(/* string: url da página */)

And apply the CSS styles you want in the returned string, and you can even create a "version" of the original page on your server, with your own styles and scripts.