Bootstrap nitpicks

Switching to the new styling has mostly been OK, but...

- [ ] `` gets no styling, and the accordion stuff is pretty heavy/weird
- [ ] `role=switch` is effectively broken (were these a good idea anyway?)
- [ ] checkbox sizing is poor
- [ ] Overpass importer's "save a copy" checkbox isn't placed well
- [ ] Overpass importer's polygon draw tool needs to switch to new styes
- [ ] Support offline mode with pmtiles for basemaps

該 issue 列出了專案中 Bootstrap 元件存在的幾個樣式問題。首先檢查使用 ``、`role=switch`、核取方塊以及 Overpass importer UI 的 Svelte 元件。尋找現有的 CSS 類別或 Bootstrap 覆寫樣式。檢查 Overpass importer 的 polygon draw tool 和 pmtiles basemap integration 是否存在樣式不一致。要在本機測試變更，需要執行 Svelte app 以查看視覺修正效果。

由索引模型根據 Issue 內容生成。