fix: improve counter reset compatibility for headings and TOC

[returnToInnocence]

对应 fix issue

• fix: 二级标题从 3 开始，对应三级标题渲染异常 #189

PR 描述

优化标题和目录样式，增强计数器兼容性。更新标题和目录的计数器重置逻辑，确保在缺失上级标题时能够正确递增。保留备用支持以提高兼容性。

测试验证如下

1. 目录测试
   

2. 标题测试
   

[Copilot]

Pull Request Overview

This PR enhances the counter reset logic for headings and the table of contents (TOC) to ensure proper numbering even when higher-level headings are missing, while retaining fallback support for older browsers.

• Added counter-reset declarations alongside existing counter-set in TOC styles for broader compatibility.
• Mirrored these counter-reset changes in heading styles to reset lower-level counters at each heading level.
• Preserved legacy counter-set rules as a fallback mechanism.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/scss/toc.scss	Inserted counter-reset for toc-h2–toc-h6 and kept counter-set for fallback support in TOC styles.
src/scss/heading.scss	Added counter-reset alongside counter-set for heading-h2–heading-h6 in global and per‐heading rules.

Comments suppressed due to low confidence (1)

src/scss/heading.scss:57

• It would be valuable to add tests—such as automated stylelint rules or visual snapshot tests—to verify that the new counter-reset logic produces the correct numbering when parent headings are omitted.

  counter-reset: heading-h2 heading-h3 heading-h4 heading-h5 heading-h6;

[Copilot]

[nitpick] The repeated counter-reset and counter-set declarations across each heading level introduce duplication. Consider extracting these into an SCSS mixin or using a loop over heading levels to reduce repetition and simplify future updates.

Suggested change

	counter-reset: toc-h2 toc-h3 toc-h4 toc-h5 toc-h6;
	// 保留 counter-set 作为备用支持
	counter-set: toc-h2 0 toc-h3 0 toc-h4 0 toc-h5 0 toc-h6 0;
	}
	.md-toc-h2 {
	// 确保 h2 重置 h3 及其后续计数器
	counter-reset: toc-h3 toc-h4 toc-h5 toc-h6;
	counter-set: toc-h3 0 toc-h4 0 toc-h5 0 toc-h6 0;
	}
	.md-toc-h3 {
	counter-reset: toc-h4 toc-h5 toc-h6;
	counter-set: toc-h4 0 toc-h5 0 toc-h6 0;
	}
	.md-toc-h4 {
	counter-reset: toc-h5 toc-h6;
	counter-set: toc-h5 0 toc-h6 0;
	}
	.md-toc-h5 {
	counter-reset: toc-h6;
	counter-set: toc-h6 0;
	}
	@include reset-counters(toc-h2, toc-h3, toc-h4, toc-h5, toc-h6);
	}
	@for $i from 2 through 6 {
	.md-toc-h#{$i} {
	@include reset-counters(
	#{'toc-h' + ($i + 1)},
	#{'toc-h' + ($i + 2)},
	#{'toc-h' + ($i + 3)},
	#{'toc-h' + ($i + 4)}
	);
	}
	}

[Keldos-Li]

@copilot 真是酷, 我都想不到这种SCSS写法。不过感觉为了简明易懂，还是不要循环了，直白写吧）

[returnToInnocence]

@Keldos-Li 果然 llm 能够想到的解法更优，不过确实这样的话维护起来后面如果语法不熟读着可能就不好理解一些💡

[Keldos-Li]

我明确了一下注释。在新版的typora下这么写在我的mac上测试应该是可行的

[RalXYZ]

感谢。
辛苦看下，是否把行末从 LF 改成 CRLF 了，导致 diff 里看起来所有行都改了。如果是这样，辛苦改回原样。

[returnToInnocence]

感谢。
辛苦看下，是否把行末从 LF 改成 CRLF 了，导致 diff 里看起来所有行都改了。如果是这样，辛苦改回原样。

很有可能⊙∀⊙！晚一点我就去看一下，感谢指点🤩

[returnToInnocence]

感谢。 辛苦看下，是否把行末从 LF 改成 CRLF 了，导致 diff 里看起来所有行都改了。如果是这样，辛苦改回原样。

感谢 @RalXYZ 指点，确实是我忽略了行尾符🫡，已经修改完毕！

[RalXYZ]

@returnToInnocence 我又做了些改动，辛苦看下现在在你的老版本的 typora 上，编号是否符合预期
下面的构建产物是我修改后的，在你的设备上 把主题安装上看看
构建产物： https://github.com/Keldos-Li/typora-latex-theme/actions/runs/16397799867/artifacts/3571782601