no font is set in circuit

now in `block.typ` the radius is optional
and the font can be set in the canvas

src/circuit.typ

@@ -9,6 +9,5 @@
 /// - length (length, ratio): Optional base unit
 /// -> none
 #let circuit(body, length: 2em) = {
-  set text(font: "Source Sans 3")
   canvas(length: length, body)
 }

src/elements/block.typ

@@ -1,9 +1,9 @@
 #import "@preview/cetz:0.3.2": draw
 #import "element.typ"
 
-#let draw-shape(id, tl, tr, br, bl, fill, stroke) = {
+#let draw-shape(id, tl, tr, br, bl, fill, stroke, radius: 0.5em) = {
   let f = draw.rect(
-    radius: 0.5em,
+    radius: radius,
     inset: 0.5em,
     fill: fill,
     stroke: stroke,
@@ -27,13 +27,14 @@
   ports: (),
   ports-margins: (),
   fill: none,
+  radius: 0.5em,
   stroke: black + 1pt,
   id: "",
   debug: (
     ports: false
   )
 ) = element.elmt(
-  draw-shape: draw-shape,
+  draw-shape: draw-shape.with(radius: radius),
   x: x,
   y: y,
   w: w,