Css not getting reflected in preview mode

I am trying to override the default css of accordion from the editor itself via

tag it is not getting reflected in preview mode. Scenarion: Other application is getting the content via rest API and html ported is

title1

Content1

But in drupal side the content is modified as I have tried on other application to replicate the structure and while editing on drupal as source adding style .ckeditor-accordion-container > dl dt > a {background-color:#eff7fd;color: #000000}

But in preview mode or view mode the style is not getting overriden i am not sure what is going missing.