STEP 1: Create CSS file:-

We have to create CSS file in the following directory:

STEP 2: Give path of your CSS file:-

Now put the following code in the xml file of the report.
In this code I have inherited the “minimal_layout” template of the
layout.xml file of the report module and gave path of the CSS file.

<template id=”minimal_layout_inherit” inherit_id=”report.minimal_layout”>
<xpath expr=”//head” position=”inside”>
<link rel=’stylesheet’ href=”/<module_name>/static/src/css/<file_name>.css”/>