Narrow windows keep the sidebar open and push tool controls off-screen

[vuon9]

Summary

At narrow/mobile-sized widths, the app keeps the full sidebar visible and most tool surfaces continue using desktop-sized horizontal controls/panes. This pushes primary controls and editors off the right side of the viewport, making tools difficult or impossible to use in a small desktop window.

Affected tools

Confirmed in a 390x844 dark-mode Playwright pass across all current tools. The issue is most obvious on:

• Code Encoder
• Code Encrypter
• Hash Generator
• Code Converter
• Text Utilities
• Color Converter
• URL Inspector
• Cron Job Parser
• RegExp Tester
• Text Diff

Likely root UI area: global layout/sidebar plus shared tool controls/split panes.

Repro steps

1. Start the frontend: cd frontend && npm run dev -- --host 127.0.0.1 --port 3000.
2. Open any tool route, for example /tool/url-inspector.
3. Resize viewport/window to approximately 390x844.
4. Enable dark mode.
5. Observe that the sidebar remains full width and the tool content starts around x=280, with controls extending beyond the visible 390px viewport.

Expected

At narrow widths, the app should collapse or overlay the sidebar and stack tool controls/panes so the active tool remains usable without hidden primary controls.

Actual

Primary controls render off-screen. Example measurements from the monkey pass:

• URL Inspector: scheme/host/path inputs render from x=280 to x=440; query value input x=425 to x=585; action buttons x=593+.
• Color Converter: header actions and color formats table extend to x=606+ / x=650+.
• Cron Job Parser: field breakdown table extends to x=600+.
• Text Diff: mode/reset controls extend to x=531+.

Evidence

Generated screenshots during the run for each affected tool in dark mobile viewport. The run also recorded DOM bounding boxes showing off-screen controls.

Priority

Medium: desktop default width is usable, but this hurts small-window ergonomics and makes dark-mode/narrow-window testing miss important interaction paths.

[vuon9]

Evidence attached from the monkey pass:

• Evidence branch: https://github.com/vuon9/devtoolbox/tree/monkey-evidence-20260527/evidence/monkey-20260527

URL Inspector, 390x844 dark viewport:

Color Converter, 390x844 dark viewport:

Cron Job Parser, 390x844 dark viewport:

Text Diff, 390x844 dark viewport:

Dedupe checked before filing against existing issues: #104, #64, #63, #62, #51, #50, #31, #28, #26, #25, #24, #4. No existing open issue covered the narrow-window/sidebar overflow problem.