style(fix[fonts]): Load all used font weights and replace unsupported 650 (#11)

Browsers were synthesizing font variants for two missing weights:
`font-weight: 650` had no Fontsource file (falling back to synthetic
bold), and weight 300 — used by Furo and sphinx-design for lighter
text — was never loaded.

- **IBM Plex Sans weights**: `[400, 500, 600, 700]` → `[300, 400, 500, 600, 700]`
- **IBM Plex Mono weights**: `[400]` → `[300, 400]`
- **Badge font-weight 650 → 700**: sphinx-autodoc-pytest-fixtures,
  sphinx-gptheme, and docs custom CSS

Author: tony

CHANGES

@@ -28,6 +28,17 @@ $ uv add gp-sphinx --prerelease allow
   return annotations — alias names are preserved and linked rather than
   expanding to the underlying union or generic type (#9)
 
+### Bug fixes
+
+- Load font weight 300 for IBM Plex Sans and IBM Plex Mono
+  ([Furo](https://github.com/pradyunsg/furo) and sphinx-design use
+  `font-weight: 300` for lighter text, but the weight was never loaded,
+  causing browsers to synthesize a light variant)
+- Replace `font-weight: 650` with `700` in badge CSS across
+  `sphinx-autodoc-pytest-fixtures`, `sphinx-gptheme`, and docs (650 is not
+  a standard Fontsource weight, so browsers were synthesizing bold instead
+  of using the real font file)
+
 ### Workspace packages
 
 - `sphinx-autodoc-pytest-fixtures` — Sphinx autodocumenter for pytest fixtures.

docs/_static/css/custom.css

@@ -395,7 +395,7 @@ h4:has(> .sd-badge[role="note"][aria-label^="Safety tier:"]) {
 
 .sd-badge[role="note"][aria-label^="Safety tier:"] {
   gap: 0.28rem;
-  font-weight: 650;
+  font-weight: 700;
   letter-spacing: 0.01em;
   border: 1px solid transparent;
 }

packages/gp-sphinx/src/gp_sphinx/defaults.py

@@ -195,15 +195,15 @@ class FontConfig(_FontConfigRequired, total=False):
         "family": "IBM Plex Sans",
         "package": "@fontsource/ibm-plex-sans",
         "version": "5.2.8",
-        "weights": [400, 500, 600, 700],
+        "weights": [300, 400, 500, 600, 700],
         "styles": ["normal", "italic"],
         "subset": "latin",
     },
     {
         "family": "IBM Plex Mono",
         "package": "@fontsource/ibm-plex-mono",
         "version": "5.2.7",
-        "weights": [400],
+        "weights": [300, 400],
         "styles": ["normal", "italic"],
         "subset": "latin",
     },

packages/sphinx-autodoc-pytest-fixtures/src/sphinx_autodoc_pytest_fixtures/_static/css/sphinx_autodoc_pytest_fixtures.css

@@ -183,7 +183,7 @@ dl.py.fixture > dt .spf-badge-group {
   position: relative;  /* positioning context for the CSS-only tooltip */
   display: inline-block;
   font-size: var(--spf-badge-font-size, 0.67rem);
-  font-weight: 650;
+  font-weight: 700;
   line-height: normal;
   letter-spacing: 0.01em;
   padding: var(--spf-badge-padding-v, 0.16rem) 0.5rem;

packages/sphinx-gptheme/src/sphinx_gptheme/theme/static/css/custom.css

@@ -271,7 +271,7 @@ h4:has(> .sd-badge[role="note"][aria-label^="Safety tier:"]) {
 
 .sd-badge[role="note"][aria-label^="Safety tier:"] {
   gap: 0.28rem;
-  font-weight: 650;
+  font-weight: 700;
   letter-spacing: 0.01em;
   border: 1px solid transparent;
 }