CSS Filter Effects
Method of applying filter effects using the `filter` property to elements, matching filters available in SVG. Filter functions include blur, brightness, contrast, drop-shadow, grayscale, hue-rotate, invert, opacity, sepia and saturate.
Method of setting the transparency level of an element
#rrggbbaa hex color notation
The CSS Color Module Level 4 defines new 4 & 8 character hex notation for color to include the opacity level.
SVG (basic support)
Method of displaying basic Vector Graphics features using the embed or object elements. Refers to the SVG 1.1 spec.
css property: opacity: support for percentage opacity values
css property: shape-image-threshold: support for percentage opacity values
types: filter-function: `opacity()`
svg element: stop: stop-opacity