use\n// this to tweak colors on an as-needed basis. This aesthetic change is based on\n// WebKit's default styles, but applicable to a wider range of browsers. Its\n// usability and accessibility should be taken into account with any change.\n//\n// Example usage: change the default blue border and shadow to white for better\n// contrast against a dark gray background.\n@mixin form-control-focus($ignore-warning: false) {\n  &:focus {\n    color: $input-focus-color;\n    background-color: $input-focus-bg;\n...