Scrollbar mismatching browser theme

[chuanqisun]

Describe the bug
The light theme scrollbar is appearing when browser is using the dark theme by default

Bug area (choose one)

• Site builder: anything broken during in the GitHub action
• Reader UI: anything broken while you are reading the feed

To reproduce the bug

• N/A

Expected behavior
The scrollbar should match the default browser theme

Screenshots

Additional context
Need to add css

:root {
  color-scheme: light dark;
}