Custom sidebar width & content width for all schemes.

[ivan-nginx]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines.
• Tests for the changes have been added (for bug fixes / features).
  • Muse | Mist have been tested.
  • Pisces | Gemini have been tested.
• Docs have been added / updated (for bug fixes / features).

PR Type

What kind of change does this PR introduce?

• Bugfix.
• Feature.
• Code style update (formatting, local variables).
• Refactoring (no functional changes, no api changes).
• Build related changes.
• CI related changes.
• Documentation content changes.
• Other... Please describe:

What is the current behavior?

Issue Number(s): #150, #184
Pull Number(s): #111, #103

What is the new behavior?

1. [BR]: Removed max_content_width setting (which was only for Gemini scheme).
2. [BR]: renamed sidebar_width to sidebar.width option (moved from global to section to section under sidebar).
3. Added desktop-largest() condition and setted to >1600px. Old desktop-large() now redefined to >1200px. Added new $content-desktop-largest variable.
4. Replaced $main-desktop & $main-desktop-large variables with standard $content-desktop & $content-desktop-large for Pisces/Gemini schemes.
5. Moved $sidebar-desktop variable from global base.styl variables file to Pisces.styl (because it's only for Pisces/Gemini).
6. Moved layout global styles variables from Gemini.styl to Pisces.styl.

How to use?

Change sidebar width

In NexT _config.yml:

-# Manual define the max content width 
-# !!Only available for Gemini Scheme currently 
-# Leave it empty for the default 75% (suggest not less than 1000px) 
-#max_content_width: 1000px 
 
-# Manual define the sidebar width 
-# !!Only available for Gemini Scheme currently 
-# Leave it empty for the default 240 
-sidebar_width: 

sidebar:
  # Manual define the sidebar width. 
  # If commented, will be default for: 
  # Muse | Mist: 320 
  # Pisces | Gemini: 240 
  width: 300 

Change content width

By default, Pisces and Gemini schemes adapted under high-screen resolutions.
Muse and Mist have old 900px value with >=1600px desktop.
You can change variables in source/css/_variables/custom.styl:

$content-desktop         = XXX
$content-desktop-large   = XXX
$content-desktop-largest = XXX

For example, for Muse / Mist under high-screen resolutions:

$content-desktop         = 90%
$content-desktop-large   = 90%
$content-desktop-largest = 90%

OR

$content-desktop         = 50em
$content-desktop-large   = 55em
$content-desktop-largest = 60em

P.S. Docs will be ASAP in site. Please, be patient and wait.

Does this PR introduce a breaking change?

• Yes.
• No.

[jiangtj]

Old config max_content_width is set max-width property, but new variables is set width property in different resolution.
For me, max_content_width is performed well. And redo with below config

variables.styl
$content-desktop         = 75%
$content-desktop-large   = 75%
$content-desktop-largest = 75%

styles.styl
.header-inner {
  max-width: 1000px
}
.main-inner {
  max-width: 1000px
}
.footer-inner{
  max-width: 1000px
}
.header {
  max-width: 1000px
}

This is a little hard.