@SiddharthDixit
In your css.txt file, you have written
#base=css
css/layout.css
which is totally wrong. this should be written as
#base=css
layout.css
or
just css/layout.css
because #base property denotes the root folder.
Note. you also have to update your clientlib category name inside your page templates component
e.g. /components/structure/page/headlibs.html