Spaces/new lines don't matter in PHP they get ignored so the code above is hard to read and it is definitely not clean you should read PHP Standards Recommendations - PHP-FIG
in order to remove this "bugs" with the web design use:
https://necolas.github.io/normalize.css/
DON'T use <center> use css
DON'T use <font> use css
if you can always use css and html5