.post-sig {
  margin:12px 0 0 0;
  padding:0 20px;
  border-top:1px dashed #704C23;
}

<script type="text/javascript">
$(document).ready(function(){
$('h1.title-logo span').wrapInner('<a href="https://forum.mybb.ru/" style="color:#fff;text-decoration:none;"></a>');
$(window).scroll(function(){if($(this).scrollTop()>100){$('.scrollup').fadeIn();}else{$('.scrollup').fadeOut();}});$('.scrollup').click(function(){$("html, body").animate({scrollTop:0},600);return false;});});
function select_text(elem){if(window.getSelection){var s=window.getSelection();if(s.setBaseAndExtent){s.setBaseAndExtent(elem,0,elem,elem.innerText.length-1);}
else{var r=document.createRange();r.selectNodeContents(elem);s.removeAllRanges();s.addRange(r);}}
else if(document.getSelection){var s=document.getSelection();var r=document.createRange();r.selectNodeContents(elem);s.removeAllRanges();s.addRange(r);}
else if(document.selection){var r=document.body.createTextRange();r.moveToElementText(elem);r.select();}}
var div=document.getElementById('pun-main').getElementsByTagName('div');for(x in div){if(div[x].className=='code-box'){div[x].getElementsByClassName('legend')[0].innerHTML='<a href="#" onclick="select_text(this.parentNode.parentNode.childNodes[1].getElementsByTagName(\'pre\')[0]); return false;">Выделить код</a>';}}
$('.post-content').each(function() {$(this).html($(this).html().replace(/<p><br><br>/g,'</div><p>').replace(/<p><br>/g,'</div><p>').replace(/<\/div><p><\/p>/g,'</div>'));});
</script>