[CSSFrancis]

Follow-up to #83, stacked on it: this branch contains #83's commit plus two more. Merge #83 first and this diff shrinks to the follow-up commits, or merge this alone to land both.

Fixes

1. fontweight was lost on TeX labels. _drawMarkerText called _drawTex without weight, and _drawTex rebuilds ctx.font from opts.weight. So fontweight="bold" with "$\mathrm{Fe}_{K\alpha}$" drew in normal weight. It now passes weight: ms.fontweight.
2. A single $ changed plain labels. Any $ sent a label to _drawTex, where _texRuns treats each unescaped $ as switching math mode on or off. So "Cost $5" lost its dollar sign, and "$$$" drew nothing. Labels are now typeset only when they have an even, non-zero number of unescaped dollars, matching matplotlib's cbook.is_math_text. Axis labels are unchanged; they always go through _drawTex.

Tests: test_bold_survives_tex_typesetting (1-D and 2-D) and test_odd_dollars_stay_literal ("$$$", "Cost $5"), as screenshot tests. All four fail on #83 and pass here; test_text_style.py passes 45/45.

Example

Examples/Markers/plot_fonts_and_labels.py, a Fonts and Labels gallery page with one figure per topic:

• the panel's own title, axis labels and colorbar label with fontsize and TeX;
• size and weight;
• an outline (halo) over a busy image;
• rotation in radians about the anchor;
• a 3×3 grid of horizontal and vertical alignments, with the anchor points marked;
• math in markers (sub/superscripts, Greek, \mathrm, bold TeX) next to a plain $5 label;
• a live set(...) update.

I rendered every figure in headless Chromium to check the layout. One limitation surfaced: the mini-TeX parser doesn't support TeX spacing commands. \, draws a comma and \ drops the space, so the example uses plain spaces.

Assisted-by: claude-code:claude-opus-5-5

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.07%. Comparing base (01b6b12) to head (3ae27c7).
⚠️ Report is 26 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #85      +/-   ##
==========================================
+ Coverage   91.26%   92.07%   +0.80%     
==========================================
  Files          41       42       +1     
  Lines        5004     5489     +485     
==========================================
+ Hits         4567     5054     +487     
+ Misses        437      435       -2     

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