1. currentColor property
  2. CSS’s currentColor property (that we mostly all know and love) allows you to use the current color of an element as the value for another property. This is useful for things like borders, outlines, and box shadows. But did you know that you can adjust the transparency dynamically?

    body {
      font-family: sans-serif;
      color: lightpink;
      background-color: black;
    }
    
    div {
      padding: 16px;
      border-style: solid;
      border-color: color-mix(in srgb, transparent 60%, currentColor);
    }

    The color-mix function in CSS returns a new color value by mixing two colors together by a given percentage. The first argument is the color space, the second is the percentage, and the third is the color to mix with. Combined with currentColor, it is very useful.

  3. how I installed Sass on Ubuntu 16.04
  4. $ sudo apt-get install ruby
    $ ... 
    $ sudo gem install sass --no-user-install
    … after the second of the above invocations I got the following:
    Fetching: rb-fsevent-0.10.2.gem (100%)
    Successfully installed rb-fsevent-0.10.2
    Fetching: ffi-1.9.18.gem (100%)
    Building native extensions.  This could take a while...
    ERROR:  Error installing sass:
    ERROR: Failed to build gem native extension.
    
        current directory: /var/lib/gems/2.3.0/gems/ffi-1.9.18/ext/ffi_c
    /usr/bin/ruby2.3 -r ./siteconf20170913-1057-1vplk2n.rb extconf.rb
    mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h
    
    extconf failed, exit code 1
    
    Gem files will remain installed in /var/lib/gems/2.3.0/gems/ffi-1.9.18 for inspection.
    Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/ffi-1.9.18/gem_make.out
          
    … following the advice given here I then did:
    sudo apt-get install ruby-dev
    … at which point the
    sudo gem install sass --no-user-install
    succeeded.