fix sass linting errors

[marcobiedermann]

Fix the majority of sass linting errors

• ColorKeyword: Color green should be written in hexadecimal form as #008000
• Comment: Use // comments everywhere
• DuplicateProperty: Property already defined
• EmptyLineBetweenBlocks: Rule declaration should be followed by an empty line
• Indentation: Line should be indented 4 spaces, but was indented 3 spaces
• LeadingZero: 0.2 should be written without a leading zero as .2
• PropertySortOrder: Properties should be ordered alphabetically
• PseudoElement: Begin pseudo elements with double colons: ::
• Remove vendor prefixes
• Shorthand: Shorthand form for property border-color should be written more concisely as $primary-color transparent instead of $primary-color transparent $primary-color transparent
• SingleLinePerSelector: Each selector in a comma sequence should be on its own single line
• SpaceAfterComma: Commas in function arguments should be followed by a single space
• SpaceAfterPropertyColon: Colon after property should be followed by one space
• SpaceAroundOperator: $amount/2 should be written with a single space on each side of the operator: $amount / 2
• StringQuotes: Prefer single quoted strings
• TrailingSemicolon: Declaration should be terminated by a semicolon
• TrailingWhitespace: Line contains trailing whitespace
• UnnecessaryMantissa: 0.0 should be written without the mantissa as 0
• ZeroUnit: 0px should be written without units as 0

[marcobiedermann]

I'm closing this issue because this project is no longer being maintained