feat: Pagebreak headings if the page is too far advanced

Can be configured using the `heading_pagebreak_percentage` property

chapters/01-Introduction.typ

@@ -26,6 +26,13 @@ you can supply it if it is not "Introduction" using the `first_chapter_title` pa
   caption: [Code example explaining how to configure language and a different first chapter]
 )
 
+// By default, the template will *not* apply a pagebreak
+// on non-top-level headings to avoid headings without content
+// on the same page but can be enabled.
+// The threshold percentage on the page can be configured
+// by providing the `heading_pagebreak_percentage` propery like `0.7` or `none`.
+// Top-level headings will always have a (weak) pagebreak.
+
 == Bibliography
 
 As for bibliography / reference listing,

template.typ

@@ -140,6 +140,12 @@
 	// This is required to generate the content section correctly
 	first_chapter_title: "Introduction",
 
+	// Factor of page location when to pagebreak headings
+	// to avoid a heading without content on the same page.
+	// Can be disabled by setting it to none
+	// WARNING: can result in "layout did not converge within 5 attempts" issue
+	heading_pagebreak_percentage: none,
+
 	// set automatically by using the template via `#show: thesis.with(...)
 	body,
 ) = [
@@ -207,6 +213,21 @@
 		// (weak = no pagebreak on already blank pages)
 		if it.level == 1 {
 			pagebreak(weak: true)
+		} else if heading_pagebreak_percentage != none {
+			// If a heading would start at the very end of a page,
+			// it would not look right => pagebreak
+			context {
+			  let here_abs = here().position().y
+				let here_rel = here_abs.abs / page.height
+
+				if  here_rel > heading_pagebreak_percentage {
+					// Write but hide to assess location correctly
+					// Hidden will not have any influence
+					// on the output besides correct calculation
+					hide[#here_abs.abs #page.height rel: #here_rel%]
+					pagebreak(weak: true)
+				}
+			}
 		}
 
 		[

thesis.typ

@@ -36,4 +36,4 @@ but I am too lazy to explain.
 
 = Summary and Conclusion
 
-#lorem(100)
+#lorem(250)