maybe fix relative len for sized span

src/layout/widget.rs

@@ -10,7 +10,6 @@ pub trait Widget: Any {
 }
 
 pub struct SizeCtx<'a> {
-    pub screen_size: Vec2,
     pub size: Vec2,
     pub text: &'a mut TextData,
     pub textures: &'a mut Textures,