What does fuzzy distance mean in css? _html/css_WEB-ITnose

h1{  text-shadow: 5px 5px 5px #FF0000;}

Horizontal shadow 5px, vertical shadow 5px, blur distance 5px
What is the effect of the blur distance here?
Is it completely blurry at 5px? But the effect doesn't look like it. . .

Reply to discussion (solution)

This is the effect of text projection. Blur is the effect obtained by reference to the original text. 0 means no blur effect, which is the clearest, original effect. The copy of , the larger the value, the blurrier it becomes. When it reaches a certain value, it becomes a fog and cannot be seen clearly.