Zend certified PHP/Magento developer

New extended theme from luma doesnt show style-l or style-m css

I have created the registration.php, theme.xml,composer.json in app/design/frontend/myvendorname/themename_theme/ and _extends.less in app/design/frontend/myvendorname/themename_theme/web/css/source.

Ran the following commands

rm -r /home/magento/pub/static/* /home/magento/var/view_preprocessed/* /home/magento/var/cache/*

cp /root/.htaccess /home/magento/pub/static/ 
#re-copying htaccess above to static folder just in case it got lost

magento cache:flush
magento setup:static-content:deploy -f
chown -R www-data:www-data /home/magento
chmod -R 777 /home/magento

So when the magento frontend loads, everything is broken since no style-l or style-m is inherited from luma and no css from _extends.less shows up. The _extends.less only contains body{background-color:yellow;} . I have also tried with renaming _extends.less to _extend.less or _extend.css . In one of the iterations I saw the frontend load properly though WITHOUT my css when I had mistakenly not included the css folder inside the web folder.

What am I doing wrong? I have been at it for the last 2 days!