Responsive newsletter built with React.js

Hi everyone,

Here is my newsletter project. I built it with react.js. One question I have is what is the best way to set dimensions for an image within a container. Should I make the image have fixed dimensions? Or should I make the dimensions set to percentages i.e. width:100%, height: 100%?

If I fixed the dimensions, the image won't be responsive. And sometimes if I make the dimensions percentages, The dimensions become a bit unpredictable when the screen shrinks and grows.

Any advice is greatly appreciated. Thanks in advance! Happy coding :)