diff --git a/courses/223015b/slides/2025-12-19-termin-0-intro.md b/courses/223015b/slides/2025-12-19-termin-0-intro.md
index afdb5a3..af2de57 100644
--- a/courses/223015b/slides/2025-12-19-termin-0-intro.md
+++ b/courses/223015b/slides/2025-12-19-termin-0-intro.md
@@ -20,8 +20,14 @@ section.invert {
 section {
   font-size: 1.7rem;
 }
+h1 {
+  color: #1e5f8a;
+}
+section.invert h1 {
+  color: #fff;
+}
 h2 {
-  color: var(--color-highlight);
+  color: #1f2937;
 }
 pre {
   background: #0f0f23;
diff --git a/courses/223015b/slides/2025-12-19-termin-1-grundlagen-text-audio.md b/courses/223015b/slides/2025-12-19-termin-1-grundlagen-text-audio.md
index b006254..f950518 100644
--- a/courses/223015b/slides/2025-12-19-termin-1-grundlagen-text-audio.md
+++ b/courses/223015b/slides/2025-12-19-termin-1-grundlagen-text-audio.md
@@ -20,8 +20,14 @@ section.invert {
 section {
   font-size: 1.7rem;
 }
+h1 {
+  color: #1e5f8a;
+}
+section.invert h1 {
+  color: #fff;
+}
 h2 {
-  color: var(--color-highlight);
+  color: #1f2937;
 }
 pre {
   background: #0f0f23;
diff --git a/courses/223015b/slides/2026-01-09-termin-2-bild-audio-video.md b/courses/223015b/slides/2026-01-09-termin-2-bild-audio-video.md
index 634a15d..01cb67c 100644
--- a/courses/223015b/slides/2026-01-09-termin-2-bild-audio-video.md
+++ b/courses/223015b/slides/2026-01-09-termin-2-bild-audio-video.md
@@ -20,8 +20,14 @@ section.invert {
 section {
   font-size: 1.7rem;
 }
+h1 {
+  color: #1e5f8a;
+}
+section.invert h1 {
+  color: #fff;
+}
 h2 {
-  color: var(--color-highlight);
+  color: #1f2937;
 }
 pre {
   background: #0f0f23;
@@ -474,7 +480,7 @@ Lösung: Portfolio-Websites (eigene Kontrolle)
 
 ---
 
-![bg right:25%](./assets/qr/squoosh.png)
+![bg contain right:25%](./assets/qr/squoosh.png)
 
 # Hands-On: Kompression vergleichen
 
diff --git a/courses/223015b/slides/2026-01-23-termin-3-speichermedien-schnittstellen.md b/courses/223015b/slides/2026-01-23-termin-3-speichermedien-schnittstellen.md
index 0e3b4e4..598fb86 100644
--- a/courses/223015b/slides/2026-01-23-termin-3-speichermedien-schnittstellen.md
+++ b/courses/223015b/slides/2026-01-23-termin-3-speichermedien-schnittstellen.md
@@ -20,8 +20,14 @@ section.invert {
 section {
   font-size: 1.7rem;
 }
+h1 {
+  color: #1e5f8a;
+}
+section.invert h1 {
+  color: #fff;
+}
 h2 {
-  color: var(--color-highlight);
+  color: #1f2937;
 }
 pre {
   background: #0f0f23;
diff --git a/courses/223015b/slides/2026-01-30-termin-4-distribution-apis-zukunft.md b/courses/223015b/slides/2026-01-30-termin-4-distribution-apis-zukunft.md
index 33b0299..b22808d 100644
--- a/courses/223015b/slides/2026-01-30-termin-4-distribution-apis-zukunft.md
+++ b/courses/223015b/slides/2026-01-30-termin-4-distribution-apis-zukunft.md
@@ -20,8 +20,14 @@ section.invert {
 section {
   font-size: 1.7rem;
 }
+h1 {
+  color: #1e5f8a;
+}
+section.invert h1 {
+  color: #fff;
+}
 h2 {
-  color: var(--color-highlight);
+  color: #1f2937;
 }
 pre {
   background: #0f0f23;
diff --git a/courses/223015b/slides/2026-xx-xx-termin-5-vertiefung-offene-fragen.md b/courses/223015b/slides/2026-xx-xx-termin-5-vertiefung-offene-fragen.md
index 20d6b1d..ee01d2e 100644
--- a/courses/223015b/slides/2026-xx-xx-termin-5-vertiefung-offene-fragen.md
+++ b/courses/223015b/slides/2026-xx-xx-termin-5-vertiefung-offene-fragen.md
@@ -20,8 +20,14 @@ section.invert {
 section {
   font-size: 1.7rem;
 }
+h1 {
+  color: #1e5f8a;
+}
+section.invert h1 {
+  color: #fff;
+}
 h2 {
-  color: var(--color-highlight);
+  color: #1f2937;
 }
 pre {
   background: #0f0f23;