[CSSFrancis]

Follow-up to CSSFrancis#83, based on its branch, so merging this adds two commits to CSSFrancis#83.

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 CSSFrancis#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

[CSSFrancis]

Superseded by CSSFrancis#85 (same branch, opened against main so CI runs).