fix(sticky): add default width for content

[LeeJim]

🤔 这个 PR 的性质是？

• 日常 bug 修复

🔗 相关 Issue

fix #194

💡 需求背景和解决方案

fixed 状态下丢失宽度。
通过增加默认宽度 100% 解决

📝 更新日志

• fix(Sticky): 修复 fixed 状态下丢失宽度的问题

• 本条 PR 不需要纳入 Changelog

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⚠️ 请自检并全部勾选全部选项。⚠️

• 文档已补充或无须补充
• 代码演示已提供或无须提供
• TypeScript 定义已补充或无须补充
• Changelog 已提供或无须提供

[github-actions]

[github-actions]

Size Change: +16 B (0%)

Total Size: 244 kB

Filename	Size	Change
./dist/tdesign.js	124 kB	+9 B (0%)
./dist/tdesign.min.js	74.8 kB	+7 B (0%)

ℹ️ View Unchanged

Filename	Size
./dist/tdesign.css	23.3 kB
./dist/tdesign.min.css	21.6 kB

[github-actions]

Size Change: +16 B (0%)

Total Size: 244 kB

Filename	Size	Change
./dist/tdesign.js	124 kB	+9 B (0%)
./dist/tdesign.min.js	74.8 kB	+7 B (0%)

ℹ️ View Unchanged

Filename	Size
./dist/tdesign.css	23.3 kB
./dist/tdesign.min.css	21.6 kB

[github-actions]

Size Change: +16 B (0%)

Total Size: 244 kB

Filename	Size	Change
./dist/tdesign.js	124 kB	+9 B (0%)
./dist/tdesign.min.js	74.8 kB	+7 B (0%)

ℹ️ View Unchanged

Filename	Size
./dist/tdesign.css	23.3 kB
./dist/tdesign.min.css	21.6 kB