add consistent dark theme styling across all slides

- add CSS variables for colors (foreground, highlight, dimmed)
- style code blocks with dark background and blue accent
- improve inline code appearance
- update link colors
- add deploy restriction to CLAUDE.md

slides/2026-01-23-termin-3-speichermedien-schnittstellen.md

@@ -9,11 +9,38 @@ title: Dateiformate, Schnittstellen, Speichermedien & Distributionswege
 ---
 
 <style>
+:root {
+  --color-foreground: #1a1a2e;
+  --color-highlight: #5da9e9;
+  --color-dimmed: #4a4a6a;
+}
+section.invert {
+  --color-foreground: #fff;
+}
 section {
   font-size: 1.7rem;
 }
 h2 {
-  color: var(--color-dimmed);
+  color: var(--color-highlight);
+}
+pre {
+  background: #0f0f23;
+  color: #5da9e9;
+  border-radius: 8px;
+  border-left: 3px solid #5da9e9;
+}
+pre code {
+  background: transparent;
+  color: inherit;
+}
+code {
+  background: #1a1a2e;
+  color: #5da9e9;
+  padding: 0.15em 0.4em;
+  border-radius: 4px;
+}
+a {
+  color: var(--color-highlight);
 }
 </style>