Have you got troubles with your prestashop template after updating to 1.5.4.1 version? There is a quick fix for this issue. For the first, you have to open the themes directory. Open the header.tpl file located in your theme. You've got there something like:
<div id="header_right" class="grid_6 omega"> {$HOOK_TOP} </div>
all you have to do is to use grid_9 instead the grid_6:
<div id="header_right" class="grid_9 omega"> {$HOOK_TOP} </div>
If you've got troubles with the logo (white space between the menu and top of the page) open the file: themes/your_theme/css/global.css and look for:
#header_logo { float: left; display: block; margin-top: 30px; }
change it to:
#header_logo { position: absolute; top: 30px; z-index: 1; }