I cannot made changings in Point-of-sale page

Hello everyone, I am working on erpnext. My task is to change the layout of Erp next Point of sale page. I have tried by changing the css of all files containing POS css. But it is not working. I am already on developer mode.Following commands :
bench build
bench migrate
bench restart
I have to change This page to

this :

For Modifying Css, First you need to create an App.

Find hooks.py and modify app_include_css = “/assets/app-name/css/css_name.css”

Then create a file in app-name/css/css_name.css
Put all css values which need to override.