fix(a11y): preserve report focus and data contrast

.Jules/palette.md

@@ -23,3 +23,10 @@
 ## 2026-08-04 - Status Semantics and Numeric Alignment for Reports
 **Learning:** Explicit status semantics can make conditionally rendered empty states easier to discover with assistive technology, while tabular numerals improve visual comparison of metric columns. Focus-reveal behavior must not depend only on `:focus-visible`, and hover styling must not reduce the contrast of unrelated rows.
 **Action:** Use `role="status"` for genuine conditionally rendered status messages, apply `font-variant-numeric: tabular-nums` to numeric report tables, reveal skip links on `:focus`, retain a visible `:focus-visible` indicator, and avoid opacity-based dimming of non-hovered content.
+## 2026-08-05 - Avoid Dimming Non-Hovered Content
+**Learning:** Using CSS `opacity: 0.5` on non-hovered rows in data charts and tables violates WCAG contrast requirements and harms legibility for visually impaired users.
+**Action:** Avoid opacity-based dimming of non-hovered content to maintain sufficient contrast when users interact with components like charts or data tables.
+
+## 2026-08-05 - Ensure Hidden Elements Reveal on Any Focus
+**Learning:** Depending solely on `:focus-visible` to reveal hidden accessibility elements (like 'skip-to-content' links) can fail in some browsers or non-visual focus mechanisms, effectively hiding them from users who need them.
+**Action:** Ensure hidden accessibility elements are revealed on both `:focus` and `:focus-visible` states to support full keyboard accessibility.

python/fast_mlsirm/report.py

@@ -573,6 +573,7 @@ def _css() -> str:
   font-weight: bold;
 }
 
+.skip-link:focus,
 .skip-link:focus-visible {
   top: 0;
   outline: 3px solid var(--teal);
@@ -694,10 +695,6 @@ def _css() -> str:
   margin-bottom: 16px;
 }
 
-.bar-chart:hover .bar-row:not(:hover) {
-  opacity: 0.5;
-}
-
 .bar-row {
   display: grid;
   grid-template-columns: minmax(104px, 180px) 1fr minmax(64px, auto);
@@ -830,10 +827,6 @@ def _css() -> str:
   background: var(--hover-bg);
 }
 
-tbody:hover tr:not(:hover) {
-  opacity: 0.5;
-}
-
 .empty-state {
   margin: 0;
   padding: 14px;