fix: more sensible :margins borders

Author: cfoust

docs/src/layouts/nodes/margins.md

@@ -20,6 +20,8 @@ A `:margins` node puts transparent margins around its child allowing the current
 
 These properties set the size of the node inside of the `:margins` node; they do not refer to the width of the margins. A value of 0 for either property means that the node will use the full space available to it in that dimension.
 
+These values do not work like margins do in CSS. A value of `80` for `:cols` means that the `:margins` node will render its contents with a _maximum_ width of 80 columns and center it. The `:border` property below will only render borders if the size of the inner node (after applying `:cols`) is _smaller_ than the size of the `:margins` node.
+
 `:border`
 
 The [border style](#border-styles) for the borders around the node.

pkg/layout/margins/module.go

@@ -197,13 +197,6 @@ func (l *Margins) getInner(outer geom.Size) geom.Rect {
 		C: geom.Max(getSize(outer.C, factor.C), 1),
 	}
 
-	if value, ok := l.config.Border.GetPreset(); ok && !value.None() {
-		inner.C = geom.Max(
-			inner.C-2,
-			1,
-		)
-	}
-
 	return geom.Rect{
 		Position: outer.Center(inner),
 		Size:     inner,