Improve skins' CSS resets

[Piotrek Koszuliński]

The new samples proved that the current CSS reset rules are insufficient. For instance - margin of sourcearea's textarea, underline and color of links.

[Piotrek Koszuliński]

I've been thinking about this and I've got few observations:

1. We can't obviously create a bulletproof skin. If someone decides to style #content div { float: left; border: solid 5px red } it's his problem.
2. .cke_reset_all * {} has lower specificity than .mycontent a {}... That was really surprising for me and it's sad because it makes our reset rules less significant than usual .mycontent sometag {} styles.
3. It's pretty common to style some very specific tags (by specific I mean for instance links, but not divs or spans) with rules of specificity 1 - e.g. all links on the page, or all inputs. With this we deal pretty well thanks to our reset.
4. But it's even more common to style specific tags in some container (specified by class or id). With the id we can't do anything, but with the class we can and I saw on many occasions that our certain styles get overridden.

In my opinion links cause the biggest problem. We don't have right not a rule with specificty 11+ which clean them. Another tag which I saw touched is the sourceare and that's because it's not inside any cke_reset_all element.

I pushed ​branch:t/13119 with a manual test in which I styled content accordingly to the above rules - that we can't be bulletproof, but we can do better with specific elements rules (I chose only link and textarea) which have specificity 11 and set some reasonable (popular) styles.

I also made necessary changes to our reset.css (added .cke_reset_all a, .cke_reset_all textarea rules) and tuned related rules so they have specificity of 11+ too.

WDYT about the above? Please remember that the patch is not meant to solve all problems, but simply improve the situation for most common scenarios.

PS. This small research was pretty interesting and was a good lesson that we could use when working on CKEditor 5 or any new skin that we'll build. It proves that CSS reset should be based on rules of specificity 11+ for as many elements that we use in our UI as possible. It can't be done for moono or kama now, because if I added .cke_reset_all span for instance it would make all other rules based on classes only (specificty = 10) ignored.

[Piotrek Koszuliński]

We changed samples framework styling a little bit, so the issues that we had are gone. I'm removing milestone, but I still wait for your feedback.

[Piotrek Koszuliński]

The issue is back in SDK.

[Wiktor Walc]

In basic sample there is some empty space above the source code.

[Piotrek Koszuliński]

WFM (see ​http://dev.ckeditor.com/attachment/ticket/13119/Screen%20Shot%202015-04-21%20at%2014.51.26.png - I can't attach it in this comment because Trac can't deal with spaces :D)

[Piotrek Koszuliński]

Uh, I confirm this issue on Firefox.

[Piotrek Koszuliński]

And the problem is that it has the default display:inline, while it should have display:block to be independent on line heights and font sizes.

[Piotrek Koszuliński]

I pushed more fixes to ​branch:t/13119. Both skins are improved.

[Olek Nowodziński]

Even if something's wrong with the changes, we'll get a chance to spot it in the course of development. So better merge it sooner than later.

[Olek Nowodziński]

Merged into major in ​git:2e0eee9.