The divs overlapping when minimizing the browser

Question

This is my two divs:

This is the screen:

when I minimuse the browser, this overlapping happens

what should I do please?

To make it clear

the left div size is keep static even when I mimizie the browser, that is why the right div becoems over the left div

Edit2

when i tried Ruddy's solution, I got this:

Answer 1

好吧，它可以通过响应式设计完美解决，但是您可以尝试的一件事是对大多数html元素使用percents（％）来管理元素重叠问题，这可能会帮助您扩展某些范围，否则响应式网页设计是必要的解决方案！

Answer 2

Try min-width on the right hand container div.

Eg

min-width: 200px;