Add citation utility class and improve grid naming

- Rename layout-2col grid area 'footer' to 'buffer' for clarity
- Add .cite utility class for bottom-left citations
- Include citation examples in both demo presentations
- Document citation usage in README

1 files changed, 5 insertions, 3 deletions

diff --git a/demo-standard.md b/demo-standard.md
index 20d887f..1e1ea75 100644
--- a/demo-standard.md
+++ b/demo-standard.md
@@ -72,13 +72,15 @@ A minimal, grid-based setup for Marp presentations:
 
 The TF-IDF model for term weighting:
 
-$$\text{tf-idf}(t, d, D) = \text{tf}(t, d) \times \text{idf}(t, D)$$
+$\text{tf-idf}(t, d, D) = \text{tf}(t, d) \times \text{idf}(t, D)$
 
 Where term frequency is:
-$$\text{tf}(t, d) = \frac{f_{t,d}}{\sum_{t'\in d} f_{t',d}}$$
+$\text{tf}(t, d) = \frac{f_{t,d}}{\sum_{t'\in d} f_{t',d}}$
 
 And inverse document frequency:
-$$\text{idf}(t, D) = \log \frac{|D|}{|\{d \in D : t \in d\}|}$$
+$\text{idf}(t, D) = \log \frac{|D|}{|\{d \in D : t \in d\}|}$
+
+<div class="cite">[Sparck Jones, 1972]</div>
 
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