fix(manim-video): recommend monospace fonts — proportional fonts have broken kerning in Pango

Manim's Pango text renderer produces broken kerning with proportional
fonts (Helvetica, Inter, SF Pro, Arial) at all sizes and resolutions.
Characters overlap and spacing is inconsistent. This is a fundamental
Pango limitation.

Changes:
- Recommend Menlo (monospace) as the default font for ALL text
- Proportional fonts only acceptable for large titles (>=48, short strings)
- Set minimum font_size=18 for readability
- Update all code examples to use MONO='Menlo' pattern
- Remove Inter/Helvetica/SF Pro from recommendations

skills/creative/manim-video/SKILL.md

@@ -108,14 +108,18 @@ project-name/
 
 ### Fonts
 
-Always specify fonts explicitly — the default renders poorly. See `references/visual-design.md` for full recommendations.
+**Use monospace fonts for all text.** Manim's Pango renderer produces broken kerning with proportional fonts at all sizes. See `references/visual-design.md` for full recommendations.
 
 ```python
-Text("Title", font_size=48, font="Inter", weight=BOLD)       # body text
-Text("code()", font_size=24, font="JetBrains Mono")           # monospaced
-MathTex(r"\nabla L")                                           # math (uses LaTeX)
+MONO = "Menlo"  # define once at top of file
+
+Text("Fourier Series", font_size=48, font=MONO, weight=BOLD)  # titles
+Text("n=1: sin(x)", font_size=20, font=MONO)                  # labels
+MathTex(r"\nabla L")                                            # math (uses LaTeX)
 ```
 
+Minimum `font_size=18` for readability.
+
 ### Per-Scene Variation
 
 Never use identical config for all scenes. For each scene:
@@ -141,11 +145,12 @@ BG = "#1C1C1C"
 PRIMARY = "#58C4DD"
 SECONDARY = "#83C167"
 ACCENT = "#FFFF00"
+MONO = "Menlo"
 
 class Scene1_Introduction(Scene):
     def construct(self):
         self.camera.background_color = BG
-        title = Text("Why Does This Work?", font_size=48, color=PRIMARY)
+        title = Text("Why Does This Work?", font_size=48, color=PRIMARY, weight=BOLD, font=MONO)
         self.add_subcaption("Why does this work?", duration=2)
         self.play(Write(title), run_time=1.5)
         self.wait(1.0)

skills/creative/manim-video/references/visual-design.md

@@ -60,35 +60,40 @@ BG="#0A0A0A"; PRIMARY="#00F5FF"; SECONDARY="#FF00FF"; ACCENT="#39FF14"
 
 ## Font Selection
 
-Manim's default `Text()` uses the system's default sans-serif font, which often renders with poor kerning. Always specify a font explicitly.
+**Use monospace fonts for all text.** Manim's Pango text renderer produces broken kerning with proportional fonts (Helvetica, Inter, SF Pro, Arial) at all sizes and resolutions. Characters overlap and spacing is inconsistent. This is a fundamental Pango limitation, not a Manim bug.
+
+Monospace fonts have fixed character widths — zero kerning issues by design.
 
 ### Recommended Fonts
 
 | Use case | Font | Fallback |
 |----------|------|----------|
-| Body text, titles | `"Inter"`, `"SF Pro Display"` | `"Helvetica Neue"`, `"Arial"` |
-| Code, terminal | `"JetBrains Mono"`, `"SF Mono"` | `"Menlo"`, `"Courier New"` |
-| Math labels | Use `MathTex` (renders via LaTeX, not system fonts) | — |
+| **All text (default)** | `"Menlo"` | `"Courier New"`, `"DejaVu Sans Mono"` |
+| Code, labels | `"JetBrains Mono"`, `"SF Mono"` | `"Menlo"` |
+| Math | Use `MathTex` (renders via LaTeX, not Pango) | — |
 
 ```python
-# Clean body text
-title = Text("Gradient Descent", font_size=48, font="Inter", weight=BOLD)
+MONO = "Menlo"  # define once at top of file
 
-# Monospaced code
-code_label = Text("loss.backward()", font_size=24, font="JetBrains Mono")
+title = Text("Fourier Series", font_size=48, color=PRIMARY, weight=BOLD, font=MONO)
+label = Text("n=1: (4/pi) sin(x)", font_size=20, color=BLUE, font=MONO)
+note = Text("Convergence at discontinuities", font_size=18, color=DIM, font=MONO)
 
 # Math — always use MathTex, not Text
 equation = MathTex(r"\nabla L = \frac{\partial L}{\partial w}")
 ```
 
+### When Proportional Fonts Are Acceptable
+
+Large title text (font_size >= 48) with short strings (1-3 words) can use proportional fonts without visible kerning issues. For anything else — labels, descriptions, multi-word text, small sizes — use monospace.
+
 ### Font Availability
 
-Not all fonts are installed on all systems. Manim falls back silently to a default if the font is missing. Use widely available fonts:
-- **macOS**: SF Pro Display, SF Mono, Menlo, Helvetica Neue
-- **Linux**: DejaVu Sans, Liberation Sans, Ubuntu, Noto Sans
-- **Cross-platform**: Inter (install via Google Fonts), JetBrains Mono (install from jetbrains.com)
+- **macOS**: Menlo (pre-installed), SF Mono
+- **Linux**: DejaVu Sans Mono (pre-installed), Liberation Mono
+- **Cross-platform**: JetBrains Mono (install from jetbrains.com)
 
-For maximum portability, use `"Helvetica Neue"` (body) and `"Menlo"` (code) — both available on macOS and have Linux equivalents.
+`"Menlo"` is the safest default — pre-installed on macOS, and Linux systems fall back to DejaVu Sans Mono.
 
 ### Fine-Grained Text Control
 
@@ -99,15 +104,15 @@ For maximum portability, use `"Helvetica Neue"` (body) and `"Menlo"` (code) —
 MarkupText('<span letter_spacing="6000">HERMES</span>', font_size=18, font="Menlo")
 
 # Bold specific words
-MarkupText('This is <b>important</b>', font_size=24)
+MarkupText('This is <b>important</b>', font_size=24, font="Menlo")
 
 # Color specific words
-MarkupText('Red <span foreground="#FF6B6B">warning</span>', font_size=24)
+MarkupText('Red <span foreground="#FF6B6B">warning</span>', font_size=24, font="Menlo")
 ```
 
-### Text Rendering Quality
+### Minimum Font Size
 
-Manim's text rendering quality depends heavily on output resolution. At `-ql` (480p), text kerning looks noticeably poor. Always preview text-heavy scenes at `-qm` (720p) or higher. See `references/rendering.md` for quality preset guidance.
+`font_size=18` is the minimum for readable text at any resolution. Below 18, characters become blurry at `-ql` and barely readable even at `-qh`.
 
 ## Visual Hierarchy Checklist