News homepage using grid and flexbox

This is my solution to the news homepage, I only use HTML, CSS and Javascript, its responsive for all devices. I had some problems to set the size of some images, I still have some doubts, because at first I wanted to use percentages, but it worked differently in firefox and chrome, I ended up setting a fixed value. Finally the navbar had some strange behaviours, already in mobile devices, when just loaded the page had a space on the right where I hid the navbar and the overflow-x: hidden did not work, I put it in the body tag, finally I find a solution on internet, but I'm not clear why that happened. If you see some mistakes or bad practice, please, let me know, I appreciate any feedback, Thanks