My Suggestion :
Bootstrap[
^] is one of the best solution for the variant screen device 's UI development.
A percentage means that depending on the width of the window, the width will change. A pixel width means that no matter the window size, the width will always be the same.
One has application for fluid-layouts (%) and the other for fixed-width layouts (px).
TorubleShooting : Try setting
style="float:left;"
For your application where the size of the screen is not fixed , go for (%). And the child content inside the
must to be specified with (%) percentage.