v0.40.3

This release fixes some long-running bugs:

• Decrease package size by excluding non-essential files (thanks @vinkla)
• Add JSON and HTML to files to check for CSS as well (thanks @seandellis)
• Support HSL in all files just like HSLA (thanks @paulequilibrio)
• Fix marker background attachment (thanks @JoryHogeveen)
• Basic support for Javascript variables (thanks @imerkle)
• Fix invisible gutter (thanks @hossamyehia)