If you added the following lines to your layout's <style> section, the flag will have sam width, but different height:
img.s2t-flag {
width: 70px;
height: auto;
}
You may also use the follwoing code to fix width and height, but will then display the flags uf UK and Germany with a wrong aspect ratio.
img.s2t-flag {
width: 62px;
height: 42px;
}