**Problem:** When instructions are long, the formatting in `PassFailJFrame` looks off:
1. When the instructions are displayed on the screen for the first time, the HTML is scrolled to the bottom, which isn't convenient; 2. Numbers above 10 in the list are clipped on the left; 3. No border around the HTML text. These problems were found while converting the instructions for `test/jdk/javax/accessibility/TestJCheckBoxToggleAccessibility.java` in https://github.com/openjdk/jdk/pull/23436. <details> <summary>Screenshots of the instructions</summary> The instructions are scrolled to the bottom when the test starts:  The number 10 in the list is clipped on the left:  The headings _“Testing with…”_ are flushed to the left, there's no additional space between the scroll pane border and the text. </details> **Fix:** 1. Adjust the list margins to accommodate for longer text; 2. Install the text border to either text instruction component; 3. Scroll the text to the top. <details> <summary>Screenshot of the instructions <i>with the fix</i></summary> The stated issues are resolved:  </details> ------------- Commit messages: - 8350260: Improve HTML instruction formatting in PassFailJFrame Changes: https://git.openjdk.org/jdk/pull/23674/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23674&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8350260 Stats: 7 lines in 1 file changed: 2 ins; 1 del; 4 mod Patch: https://git.openjdk.org/jdk/pull/23674.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/23674/head:pull/23674 PR: https://git.openjdk.org/jdk/pull/23674
