[Bug] Markdown bold rendering too weak / invisible in OpenCode Desktop Markdown

Description

In OpenCode Desktop, Markdown bold **text** is rendered too weakly or not visibly different from normal text. It is hard to distinguish bold and non-bold content.

In comparison, the same **text** renders correctly on GitHub/web.

Steps to Reproduce

1. Open OpenCode Desktop
2. Send or view a message containing **Je m'appelle Haoran.** and Je m'appelle Haoran.
3. Observe the two lines look identical

Expected

Bold text should be clearly thicker/darker than normal text.

Actual

Bold and normal text look almost the same, no clear visual difference.

Environment

• App: OpenCode Desktop
• OS: macOS (darwin)
• Screenshot: attached

Suggestion

Increase font-weight for strong / b to 700+ or add distinct color, do not rely on subtle weight change.