Enhance Rspress theme visual design with modern interactions and depth

[Copilot]

Implements 5 targeted style improvements to the Rspress documentation theme for enhanced visual aesthetics and modern UI patterns.

Changes

Buttons (components/Button/index.scss)

• Cubic-bezier transitions with shadow depth and lift effects
• Brand buttons: translateY(-1px) + shadow progression (2px→4px on hover)
• Alt buttons: dynamic border color → brand color on hover

Scrollbars (styles/scrollbar.scss)

• Width: 4px → 6px for improved visibility
• Thumb opacity: 2.4x increase (light), 1.5x increase (dark)

Code blocks (components/CodeBlock/index.scss)

• Base shadow + enhanced hover state for depth perception
• Smooth shadow transition on interaction

Feature cards (components/HomeFeature/index.scss)

• Hover: 4px lift + brand-tinted shadow (rgba(0, 149, 255, 0.12))
• Icon scale (1.05) + border color transition

Sidebar navigation (components/Sidebar/SidebarItem.scss)

• Active items: 3px brand-colored left border accent
• Compensated padding for alignment

Visual Impact

Before:

After:

All changes use existing CSS variables and maintain backward compatibility.

Original prompt

要求使用 Gemini 3 Pro
对 Rspress 文档站进行样式优化，找出 5 处你认为最合适修改的地方，让样式更加美观

最终你应该修改 packages/core/theme 下的文件，这是 Rspress 的主题样式所在

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[github-actions]

Rsdoctor Bundle Diff Analysis

📁 web

Path: website/doc_build/web/rsdoctor-data.json

Metric	Current	Baseline	Change
📊 Total Size	14.3 MB	14.3 MB	1017.0 B (0.0%)
📄 JavaScript	13.8 MB	13.8 MB	0 B (0.0%)
🎨 CSS	110.8 KB	109.8 KB	1017.0 B (0.9%)
🌐 HTML	0 B	0 B	N/A
📁 Other Assets	497.3 KB	497.3 KB	0 B (0.0%)

📦 Download Diff Report: web Bundle Diff

Generated by Rsdoctor GitHub Action