docs/_static/custom.css: sync with amaranth upstream.

docs/_static/custom.css

@@ -20,3 +20,17 @@ a { text-decoration: underline; }
 
 /* Many of our diagnostics are even longer */
 .rst-content pre.literal-block, .rst-content div[class^="highlight"] pre, .rst-content .linenodiv pre { white-space: pre-wrap; }
+
+/* Work around https://github.com/readthedocs/sphinx_rtd_theme/issues/1301 */
+.py.property { display: block !important; }
+
+/* Avoid excessively tiny font in the sidebar */
+.wy-menu-vertical li.toctree-l2, .wy-menu-vertical li.toctree-l3, .wy-menu-vertical li.toctree-l4 { font-size: 0.97em; }
+/* For some cursed reason the RTD theme was decreasing the font size twice! */
+.wy-menu-vertical a { font-size: 100%; }
+
+/* Work around images in docstrings being glued to the paragraph underneath */
+.rst-content section dd>img { margin-bottom: 24px; }
+
+/* No switchable color schemes */
+img { color-scheme: light; }