diff --git a/Makefile b/Makefile
index b137b62..27fc053 100644
--- a/Makefile
+++ b/Makefile
@@ -1,48 +1,92 @@
 # Makefile for Marp Slides Project
 
-.PHONY: help build dev watch pdf html clean install deploy
+.PHONY: help build dev watch pdf html clean install deploy assemble
+
+# Slide components
+SLIDES_DIR = slides
+BUILD_DIR = build
+HEADER = $(SLIDES_DIR)/_frontmatter.md
+INTRO = $(SLIDES_DIR)/_intro.md
+OUTRO = $(SLIDES_DIR)/_outro.md
+
+# Termin files (date-topic naming convention)
+TERMIN_1 = 2025-12-19-termin-1-grundlagen-text-audio
+TERMIN_2 = 2026-01-09-termin-2-bild-audio-video
+TERMIN_3 = 2026-01-23-termin-3-speichermedien-schnittstellen
+TERMIN_4 = 2026-01-30-termin-4-distribution-apis-zukunft
+TERMIN_5 = 2026-xx-xx-termin-5-vertiefung-offene-fragen
+TERMINS = $(TERMIN_1) $(TERMIN_2) $(TERMIN_3) $(TERMIN_4) $(TERMIN_5)
 
 # Default target
 help:
 	@echo "Available commands:"
-	@echo "  make build    - Build slides from Markdown"
-	@echo "  make dev      - Start development server with live reload"
-	@echo "  make watch    - Watch for changes and rebuild automatically"
-	@echo "  make pdf      - Export slides to PDF format"
-	@echo "  make html     - Export slides to HTML format"
-	@echo "  make clean    - Remove generated files"
-	@echo "  make install  - Install dependencies"
-	@echo "  make deploy   - Deploy slides to server"
+	@echo ""
+	@echo "  Development:"
+	@echo "    make dev        - Start dev server (browse all files at localhost:1312)"
+	@echo ""
+	@echo "  Build:"
+	@echo "    make build      - Build all slides (HTML + PDF)"
+	@echo "    make pdf        - Export all slides to PDF"
+	@echo "    make html       - Export all slides to HTML"
+	@echo ""
+	@echo "  Other:"
+	@echo "    make assemble   - Assemble all termin files in build/"
+	@echo "    make clean      - Remove generated files"
+	@echo "    make install    - Install dependencies"
+	@echo "    make deploy     - Deploy slides to server"
 
-# Build slides
-build:
-	@echo "Building slides..."
-	npm run build
+# Ensure build directory exists
+$(BUILD_DIR)/.exists:
+	@mkdir -p $(BUILD_DIR)
+	@touch $@
 
-# Start development server
-dev:
-	@echo "Starting development server..."
-	PORT=1312 npm run dev
+# Assemble all termin files
+assemble: $(BUILD_DIR)/.exists
+	@echo "Assembling slides..."
+	@for f in $(TERMINS); do \
+		echo "  $$f.md"; \
+		cat $(HEADER) $(INTRO) $(SLIDES_DIR)/$$f.md $(OUTRO) > $(BUILD_DIR)/$$f.md; \
+	done
+	@echo "  all.md"
+	@cat $(HEADER) $(INTRO) $(foreach t,$(TERMINS),$(SLIDES_DIR)/$(t).md) $(OUTRO) > $(BUILD_DIR)/all.md
+	@cp -r assets $(BUILD_DIR)/ 2>/dev/null || true
+
+# Development server - serves build/ with file picker
+dev: assemble
+	@echo "Starting dev server..."
+	@echo "Open: http://localhost:1312"
+	PORT=1312 npx @marp-team/marp-cli --server $(BUILD_DIR)/
 
 # Watch for changes
-watch:
-	@echo "Watching for changes..."
-	npm run watch
+watch: assemble
+	npx @marp-team/marp-cli --watch $(BUILD_DIR)/all.md
 
-# Export to PDF
-pdf:
+# Build all slides (HTML + PDF)
+build: assemble
+	@echo "Building all slides..."
+	@for f in $(TERMINS); do \
+		echo "Building $$f..."; \
+		npx @marp-team/marp-cli $(BUILD_DIR)/$$f.md -o $(BUILD_DIR)/$$f.html; \
+		npx @marp-team/marp-cli $(BUILD_DIR)/$$f.md --pdf --allow-local-files -o $(BUILD_DIR)/$$f.pdf; \
+	done
+	@echo "Building all.md..."
+	npx @marp-team/marp-cli $(BUILD_DIR)/all.md -o $(BUILD_DIR)/all.html
+	npx @marp-team/marp-cli $(BUILD_DIR)/all.md --pdf --allow-local-files -o $(BUILD_DIR)/all.pdf
+
+# Export to PDF (all slides combined)
+pdf: assemble
 	@echo "Exporting to PDF..."
-	npm run export:pdf -- --allow-local-files
+	npx @marp-team/marp-cli $(BUILD_DIR)/all.md --pdf --allow-local-files -o $(BUILD_DIR)/all.pdf
 
-# Export to HTML
-html:
+# Export to HTML (all slides combined)
+html: assemble
 	@echo "Exporting to HTML..."
-	npm run export:html
+	npx @marp-team/marp-cli $(BUILD_DIR)/all.md -o $(BUILD_DIR)/all.html
 
 # Clean generated files
 clean:
 	@echo "Cleaning generated files..."
-	rm -rf dist/ build/ *.pdf *.html
+	rm -rf $(BUILD_DIR)/ *.pdf *.html
 
 # Install dependencies
 install:
@@ -52,5 +96,5 @@ install:
 # Deploy slides
 deploy: build
 	@echo "Deploying slides..."
-	scp build/index.html tengo@tuttle.uberspace.de:/home/tengo/html/malta/
-	scp -r build/assets/ tengo@tuttle.uberspace.de:/home/tengo/html/malta/
+	scp $(BUILD_DIR)/all.html tengo@tuttle.uberspace.de:/home/tengo/html/malta/index.html
+	scp -r $(BUILD_DIR)/assets/ tengo@tuttle.uberspace.de:/home/tengo/html/malta/
diff --git a/PLAN-split-slides.md b/PLAN-split-slides.md
deleted file mode 100644
index 768556f..0000000
--- a/PLAN-split-slides.md
+++ /dev/null
@@ -1,65 +0,0 @@
-# Plan: Split index.md into multiple files
-
-## Current state
-- ~4200 lines, 5 sessions + intro/outro
-- Shared: frontmatter, styles, intro slides (title, about, schedule, survey, overview)
-- Per-session: actual content
-
-## Proposed structure
-
-```
-slides/
-├── _frontmatter.yml      # shared marp config
-├── _styles.md            # shared CSS
-├── _intro.md             # title, about, schedule, survey, overview
-├── termin-1.md           # Session 1 content
-├── termin-2.md           # Session 2 content
-├── termin-3.md           # Session 3 content
-├── termin-4.md           # Session 4 content
-├── termin-5.md           # TBA session
-└── _outro.md             # Q&A, license
-```
-
-## Makefile targets
-
-```makefile
-# Shared parts
-HEADER = slides/_frontmatter.yml slides/_styles.md
-INTRO  = slides/_intro.md
-OUTRO  = slides/_outro.md
-
-# Build single termin (intro + content + outro)
-build-termin-%:
-	cat $(HEADER) $(INTRO) slides/termin-$*.md $(OUTRO) > build/termin-$*.md
-	marp build/termin-$*.md -o build/termin-$*.html
-
-# Dev mode for single termin
-dev-%:
-	cat $(HEADER) $(INTRO) slides/termin-$*.md $(OUTRO) > build/.dev.md
-	PORT=1312 marp --server build/
-
-# Build all
-build-all:
-	cat $(HEADER) $(INTRO) slides/termin-*.md $(OUTRO) > build/all.md
-	marp build/all.md -o build/all.html
-```
-
-## Usage
-
-```bash
-make dev-1          # preview termin 1
-make dev-3          # preview termin 3
-make build-termin-2 # build termin 2
-make build-all      # build everything
-```
-
-## Trade-offs
-- Requires intermediate file generation
-- Can't use `marp --watch` directly on source (need wrapper)
-- But: clean separation, single source of truth for styles
-
-## Status
-- [ ] Learn Marp/Marpit in depth first
-- [ ] Implement split
-- [ ] Update Makefile
-- [ ] Test all targets