Your only solution is to open your page in all browsers you are going to support and check that it really renders everywhere mostly correctly. 99.9% probability that you will not be able to reach pixel-perfect identical rendering.
After you have found any discrepancy in some specific browser you open the development tools in this browser and search what CSS rule fails. After that you google about this issue seeking what browser-agnostic (if you’re lucky) or browser-specific (in most cases) hack you should introduce. After that, you change your CSS accordingly.
Repeat this method until you get satisfying result in all browsers you are going to support. Of course if your website is javascript-heavy, you have to check that all behavior on your page is identical across all browsers you are going to support.
There’s no silver bullet to instantly make your website look identically in all browsers.
solved Webpage not displaying correctly on every browser [closed]