(vii) Learn the Filter property of CSS

Filter:alpha (opacity=, finishopacity=0, style=2)???

Alpha is to set the transparency, and its basic properties are Filter:alpha (opacity,finishopacity,
style,startx,starty,finishx,finishy).
Opacity represents the number of transparencies, the selected value is 0-100, 0 is completely transparent, and 100 is opaque.
The finishopacity is used to set the transparency at the end to achieve a gradient effect. The range of values is also 0-100.style refers to the gradient type, 0 is no change, 1 is a line line gradient, 2 is a radial gradient, and 3 is an X-type gradient.

Defines a filter:alpha (opacity=), why a opacity is added later:0.7???

Standard transparency is opacity,filter only IE to use, other browsers support opacity,

(vii) Learn the Filter property of CSS