Voila le code CSS et le code HTML qui me sont fournit par Aweber:
<!-- AWeber Web Form Generator 3.0 -->
<style type="text/css">
#af-form-831156797 .af-body .af-textWrap{width:98%;display:block;float:none;}
#af-form-831156797 .af-body a{color:#094C80;text-decoration:underline;font-style:normal;font-weight:normal;}
#af-form-831156797 .af-body input.text, #af-form-831156797 .af-body textarea{background-color:#FFFFFF;border-color:#919191;border-width:1px;border-style:solid;color:#000000;text-decoration:none;font-style:normal;font-weight:normal;font-size:12px;font-family:Verdana, sans-serif;}
#af-form-831156797 .af-body input.text:focus, #af-form-831156797 .af-body textarea:focus{background-color:#FFFAD6;border-color:#030303;border-width:1px;border-style:solid;}
#af-form-831156797 .af-body label.previewLabel{display:block;float:none;text-align:left;width:auto;color:#000000;text-decoration:none;font-style:normal;font-weight:normal;font-size:12px;font-family:Verdana, sans-serif;}
#af-form-831156797 .af-body{padding-bottom:15px;padding-top:15px;background-repeat:no-repeat;background-position:inherit;background-image:none;color:#000000;font-size:11px;font-family:Verdana, sans-serif;}
#af-form-831156797 .af-footer{padding-right:15px;padding-left:15px;background-color:#transparent;border-width:1px;border-bottom-style:none;border-left-style:none;border-right-style:none;border-top-style:none;color:#000000;font-size:12px;font-family:Verdana, sans-serif;}
#af-form-831156797 .af-header{padding-bottom:9px;padding-top:9px;padding-right:10px;padding-left:10px;background-image:url('http://forms.aweber.com/images/auto/body/009/5ff/005/999');background-position:top left;background-repeat:repeat-x;background-color:#005999;border-width:1px;border-bottom-style:none;border-left-style:none;border-right-style:none;border-top-style:none;color:#FFFFFF;font-size:16px;font-family:Verdana, sans-serif;}
#af-form-831156797 .af-quirksMode .bodyText{padding-top:2px;padding-bottom:2px;}
#af-form-831156797 .af-quirksMode{padding-right:15px;padding-left:15px;}
#af-form-831156797 .af-standards .af-element{padding-right:15px;padding-left:15px;}
#af-form-831156797 .bodyText p{margin:1em 0;}
#af-form-831156797 .buttonContainer input.submit{background-image:url("http://forms.aweber.com/images/auto/gradient/button/07c.png");background-position:top left;background-repeat:repeat-x;background-color:#0057ac;border:1px solid #0057ac;color:#FFFFFF;text-decoration:none;font-style:normal;font-weight:normal;font-size:14px;font-family:Verdana, sans-serif;}
#af-form-831156797 .buttonContainer input.submit{width:auto;}
#af-form-831156797 .buttonContainer{text-align:center;}
#af-form-831156797 body,#af-form-831156797 dl,#af-form-831156797 dt,#af-form-831156797 dd,#af-form-831156797 h1,#af-form-831156797 h2,#af-form-831156797 h3,#af-form-831156797 h4,#af-form-831156797 h5,#af-form-831156797 h6,#af-form-831156797 pre,#af-form-831156797 code,#af-form-831156797 fieldset,#af-form-831156797 legend,#af-form-831156797 blockquote,#af-form-831156797 th,#af-form-831156797 td{float:none;color:inherit;position:static;margin:0;padding:0;}
#af-form-831156797 button,#af-form-831156797 input,#af-form-831156797 submit,#af-form-831156797 textarea,#af-form-831156797 select,#af-form-831156797 label,#af-form-831156797 optgroup,#af-form-831156797 option{float:none;position:static;margin:0;}
#af-form-831156797 div{margin:0;}
#af-form-831156797 fieldset{border:0;}
#af-form-831156797 form,#af-form-831156797 textarea,.af-form-wrapper,.af-form-close-button,#af-form-831156797 img{float:none;color:inherit;position:static;background-color:none;border:none;margin:0;padding:0;}
#af-form-831156797 input,#af-form-831156797 button,#af-form-831156797 textarea,#af-form-831156797 select{font-size:100%;}
#af-form-831156797 p{color:inherit;}
#af-form-831156797 select,#af-form-831156797 label,#af-form-831156797 optgroup,#af-form-831156797 option{padding:0;}
#af-form-831156797 table{border-collapse:collapse;border-spacing:0;}
#af-form-831156797 ul,#af-form-831156797 ol{list-style-image:none;list-style-position:outside;list-style-type:disc;padding-left:40px;}
#af-form-831156797,#af-form-831156797 .quirksMode{width:225px;}
#af-form-831156797.af-quirksMode{overflow-x:hidden;}
#af-form-831156797{background-color:#F0F0F0;border-color:#CFCFCF;border-width:1px;border-style:solid;}
#af-form-831156797{display:block;}
#af-form-831156797{overflow:hidden;}
.af-body .af-textWrap{text-align:left;}
.af-body input.image{border:none!important;}
.af-body input.submit,.af-body input.image,.af-form .af-element input.button{float:none!important;}
.af-body input.text{width:100%;float:none;padding:2px!important;}
.af-body.af-standards input.submit{padding:4px 12px;}
.af-clear{clear:both;}
.af-element label{text-align:left;display:block;float:left;}
.af-element{padding:5px 0;}
.af-form-wrapper{text-indent:0;}
.af-form{text-align:left;margin:auto;}
.af-header,.af-footer{margin-bottom:0;margin-top:0;padding:10px;}
.af-quirksMode .af-element{padding-left:0!important;padding-right:0!important;}
.lbl-right .af-element label{text-align:right;}
body {
}
</style>
<form method="post" class="af-form-wrapper" action="http://www.aweber.com/scripts/addlead.pl" >
<div style="display: none;">
<input type="hidden" name="meta_web_form_id" value="831156797" />
<input type="hidden" name="meta_split_id" value="" />
<input type="hidden" name="listname" value="articles_rel" />
<input type="hidden" name="redirect" value="http://www.reussirenlicence.com/et-maintenant-verifie-tes-emails/" id="redirect_cc64ddd573aabf66e2e3a4d02ee6ee0b" />
<input type="hidden" name="meta_adtracking" value="Popup" />
<input type="hidden" name="meta_message" value="1" />
<input type="hidden" name="meta_required" value="name,email" />
<input type="hidden" name="meta_tooltip" value="name||Votre prenom (sans accent),,email||Votre adresse email" />
</div>
<div id="af-form-831156797" class="af-form"><div id="af-header-831156797" class="af-header"><div class="bodyText"><p> </p></div></div>
<div id="af-body-831156797" class="af-body af-standards">
<div class="af-element">
<label class="previewLabel" for="awf_field-37067249"></label>
<div class="af-textWrap">
<input id="awf_field-37067249" type="text" name="name" class="text" value="Votre prenom (sans accent)" onfocus=" if (this.value == 'Votre prenom (sans accent)') { this.value = ''; }" onblur="if (this.value == '') { this.value='Votre prenom (sans accent)';} " tabindex="500" />
</div>
<div class="af-clear"></div></div>
<div class="af-element">
<label class="previewLabel" for="awf_field-37067250"></label>
<div class="af-textWrap"><input class="text" id="awf_field-37067250" type="text" name="email" value="Votre adresse email" tabindex="501" onfocus=" if (this.value == 'Votre adresse email') { this.value = ''; }" onblur="if (this.value == '') { this.value='Votre adresse email';} " />
</div><div class="af-clear"></div>
</div>
<div class="af-element buttonContainer">
<input name="submit" class="submit" type="submit" value="Envoyer" tabindex="502" />
<div class="af-clear"></div>
</div>
</div>
<div id="af-footer-831156797" class="af-footer"><div class="bodyText"><p> Vos coordonnées sont protégées.</p></div></div>
</div>
<div style="display: none;"><img src="http://forms.aweber.com/form/displays.htm?id=HMyMjKxs7Jzs" alt="" /></div>
</form>
<script type="text/javascript">
<!--
(function() {
var IE = /*@cc_on!@*/false;
if (!IE) { return; }
if (document.compatMode && document.compatMode == 'BackCompat') {
if (document.getElementById("af-form-831156797")) {
document.getElementById("af-form-831156797").className = 'af-form af-quirksMode';
}
if (document.getElementById("af-body-831156797")) {
document.getElementById("af-body-831156797").className = "af-body inline af-quirksMode";
}
if (document.getElementById("af-header-831156797")) {
document.getElementById("af-header-831156797").className = "af-header af-quirksMode";
}
if (document.getElementById("af-footer-831156797")) {
document.getElementById("af-footer-831156797").className = "af-footer af-quirksMode";
}
}
})();
-->
</script>
<!-- /AWeber Web Form Generator 3.0 -->
Merci encore pour votre aide !