Actually, you would modify the size of the header – and the call for your new logo image – within the relative CSS rules.
for example . . .
the CSS for the height/width of the header can be found within file path –> /nieuw/t3-assets/dev/abstract/templates.ja_mero.less.style.less.css
at line 1
.ja-header {
padding-bottom: 20px;
padding-top: 20px;
}
and the CSS rule governing the display of your logo can be found several lines below:
.logo-image a {
background-image: url("../../../templates/ja_mero/images/themes/abstract/logo.png");
background-repeat: no-repeat;
height: 41px;
width: 151px;
}
This is where you can add/modify the height and width property values to adjust them for you client’s logo
Hope That Helps