added lifeline-style

src/utils.typ

@@ -24,4 +24,20 @@
     }
   }
   return (min-i, max-i)
+}
+
+#let get-style(base-name, mods) = {
+  let style = if base-name == "lifeline" {(
+    fill: white,
+    stroke: black + 1pt
+  )}
+
+  if mods == auto {
+    return style
+  }
+  if type(mods) == dictionary {
+    return style + mods
+  }
+
+  panic("Invalid type for parameter mods, expected auto or dictionary, got " + str(type(mods)))
 }