Css can't read content in new area code for theme deploy

Question

Here is my scenario. I have create new area for my theme (Not adminhtml , frontend).
Used Developer mode and no symlinks config in admin
I have create new module simple for define new area theme

etc/di.xml

<type name="Magento\Theme\Model\View\Design">
    <arguments>
        <argument name="themes" xsi:type="array">
            <item name="vendors" xsi:type="string">Vendor/vendor</item>
        </argument>
    </arguments>
</type>

Just like magento does in frontend and adminhtml
From here i have created new area vendors

Now i go to app\design create new folder vendors and put my theme in that.
My theme path will be

app\design\vendors\Vendor\vendor

But now problem happen i can't deploy less files Got issue

The contents from the "/var/www/html/pub/static/vendors/Vendor/vendor/en_US
/css/styles-m.css" file can't be read

Content of styles-m.less below

@import (reference) 'source/_extends.less';

//
//  Magento Import instructions
//  ---------------------------------------------

//@magento_import 'source/_module.less'; // Theme modules

//
//  Media queries collector
//  ---------------------------------------------

@import 'source/_responsive.less';

@media-target: 'mobile'; // Sets target device for this file

//
//  Global variables override
//  ---------------------------------------------

@import 'source/_theme.less';

//
//  Extend for minor customisation
//  ---------------------------------------------

//@magento_import 'source/_extend.less';

All files less already created and valid but not sure why magento can't read css compiled. I expect compile will success without red error warn

Answer 1

first of delete the cache folder inside your var directory then navigate to pub-> static->front-end and delete all files from here.

now run the following commands if you are in default mode

php bin/magento setup:di:compile  
php bin/magento setup:static-content:deploy -f
php bin/magento cache:clean
php bin/magento cache:flush

hope this will solve your problem.

Answer 2

Seem my problem come from "Some less file with empty selector declare rule got issue with compile"
I'm feeling stupid here

Solutions: Remove empty rules (selector without do anything)