Guys, I'm wondering what do you put in your CVs.
Do you only mention what you master?
Do you mention things you only worked with once?
Do you mention things you only have theoretical knowledge about?
Do you mention mainstream skills ( HTML/CSS) that almost developer knows?
Please, I'm struggling.

Higlight you money skills at the beginning. And some pages later make a detailed section where you mention everything you know.

I try to keep under two pages on a CV as most people get bored after that. Headline (skills certifications (only relevant to job you are applying for))
Work experience( last three jobs or five years if you move about a lot) other experience, things you are learning, hobbies activities etc

...and a bit later in your career cite metrics on the value your systems / apps provided in terms of savings, revenue, process improvement... If you show enough value they will interview you.

I keep my CV under 2 pages, with 2 major parts : professional experience and side projects. Under professional experience I mention the projects/products I have worked on, what technology was used, how much I contributed (my role) and how have they impacted the company in terms of relevant metrics.

In case of side projects, I mention why I created it, what technologies I used and relevant link to the project

If you have to make the selection between projects, keep the more recent ones and remove those which are now old or keep their details short.

Apart from the above I also add a skills section at the top with summary of tech I am familiar with and a certification and education section at the bottom which contains bullet points with relevant info.

Hope this helps

About knowing HTML and CSS: believe me, there's a difference to being able to creating a <div> element to fully understanding HTML. And don't even get me started on CSS. If you truly know those two languages you should put it down.

I usually rank my skills in different languages, that way I can include those I do not know that well.