Fix Tor browser rendering issues for multiple choice and trace stepper

[Copilot]

Tor browser's stricter CSS handling caused multiple choice rows to superimpose and the trace stepper to render incorrectly. The root cause was flexbox layouts not behaving consistently.

Changes

CSS (common.css)

• Added high-specificity rules to force block display on list items, overriding Bootstrap's flexbox

Multiple choice (exercise.html)

• Removed d-flex class causing overlap
• Added explicit w-100 d-block to form labels

Trace stepper (stepper.html)

• Changed #statecontainer from flex to block layout
• Added explicit dimensions to .stepper-container
• Added overflow-x: auto to mermaid diagrams

/* High specificity to override Bootstrap flexbox */
ul.list-group > li.list-group-item {
    display: block;
    position: relative;
    clear: both;
}

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Rendering issues on the TOR browser</issue_title>
<issue_description>Tutor does not render well on the Tor browser.

• Some of the multiple choice sections did not render correctly: two of the rows were superimposed.
• Also the trace stepper didn't render correctly.

Issue identified by: CAV 2025 Reviewer A.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Rendering issues on the TOR browser #76

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