spacing adjusted for active section

Bug description

Certain headings see their position changed because leading whitespace is added/removed when they are active/inactive.

Steps to reproduce

Given the Quarto project:

project:
  type: website

website:
  title: "headings"
  navbar:
    left:
      - text: "Home"
        href: "index.qmd"

And an index.qmd file:

---
title: home
---

this is home.

## Level two

You may learn more.

### Level three

You may not learn more.

Preview this site, then click on the anchor icon for "Level three". Observe that the position of the heading changes.

Expected behavior

The heading position should be constant.

Actual behavior

The heading position changes.

Position before clicking "Level three" link:

Position after clicking the "Level three" link:

Your environment

No response

Quarto check output

Quarto 1.4.551
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.1.11: OK
      Dart Sass version 1.69.5: OK
      Deno version 1.37.2: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.4.551
      Path: /Users/aron/quarto/quarto-1.4.551-macos/bin

[✓] Checking tools....................OK
      TinyTeX: (not installed)
      Chromium: (not installed)

[✓] Checking LaTeX....................OK
      Using: Installation From Path
      Path: /Library/TeX/texbin
      Version: 2024

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.12.2
      Path: /opt/homebrew/opt/python@3.12/bin/python3.12
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with python3 -m pip install jupyter

[✓] Checking R installation...........OK
      Version: 4.3.3
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Library/Frameworks/R.framework/Versions/4.3-arm64/Resources/library
      knitr: 1.45
      rmarkdown: 2.26

[✓] Checking Knitr engine render......OK

Start by reproducing the issue with the minimal Quarto website and index.qmd shown in the report, then inspect the generated website's heading and anchor behavior before and after clicking the Level three link. Done means the heading position remains constant when its anchor is activated.