fix: resolve CLS issues in page layout

[ruibaby]

修复网页加载时页面布局的 CLS 问题，这个问题由 halo-dev/halo#6580 引发，因为之前的侧边栏布局采用 flex 布局，会导致在分块传输过程中，首先左边内容会自动铺满宽度，等侧边传输完成后又会改变会正常的布局，从而导致 CLS 问题，这个 PR 只是通过 CSS 规避这个问题，我建议重新考虑是否要在 Halo 中默认启用分块传输。

Screen.Recording.2024-11-15.at.21.28.18.mov

Screen.Recording.2024-11-15.at.21.29.46.mov

cc @JohnNiang

/kind improvement

修复网页加载时页面布局的 CLS 问题

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please ask for approval from ruibaby. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment