[Bug]: Instruction list has low contrast in dark mode

### Description

When viewing the [SDM site](https://intel.github.io/SDM/sdm.html) in dark mode, the menu items and instruction names in the sidebar have very low contrast with their background. In Firefox 156, the computed text color is `#0c61a4`, and the background is `#323138`. This results in:

- [1.99:1 WCAG 2 contrast ratio](https://webaim.org/resources/contrastchecker/?fcolor=0C61A4&bcolor=323138)
- [Lc -14.9 ACPA-W3 contrast value](https://apcacontrast.com/?BG=323138&TXT=0c61a4&DEV=G4g&BUF=A22)

### Screenshots

### Environment
- OS: macOS 26.6.2
- Browser: Firefox
- Version: 156.0b2

### Additional Context

- [WCAG 2.2 Contrast (Minimum) Success Criterion](https://www.w3.org/WAI/WCAG22/Understanding/contrast-minimum.html)
- [ARC Bronze Simple Mode](https://readtech.org/ARC/tests/bronze-simple-mode/)

Open the SDM site in Firefox dark mode and inspect the sidebar menu items and instruction names, comparing their computed text and background colors. Adjust the relevant styling so the text meets WCAG 2.2 contrast minimum, then verify the sidebar remains readable in dark mode.

Written by the indexing model from the issue text.