Solution 1 :

Create a div like this on absolute position

<div style="background: red; width:1px; height: 100%; position: absolute; left: 100px; top:0"></div>

Solution 2 :

You can just add an div with length of 100%, width of 2-5px and background-color of your liking.

Problem :

I have a React project. I use React-Bootstrap as UI library.

I want to create vertical lines like this, but i want it always visible over the content. How should I write CSS for this?

enter image description here