Fix #54: Make UI responsive for mobile phones

[mishankov]

Closes #54

Summary

This PR makes the string-manipulator UI responsive for better experience on mobile phones and small screens.

Changes

• Main page (): Changed grid layout from 3 columns to single column on screens < 768px
• Manipulation components (): Added to prevent overflow on narrow screens
• TextArea (): Added , , and for better mobile UX
• Docs page (): Improved container layout with max-width, centering, and responsive padding
• ManipulationBlock (): Added responsive flex layout that stacks vertically on mobile

Testing

• All Svelte type checks pass (

string-manipulator@0.0.1 check
svelte-kit sync && svelte-check --tsconfig ./tsconfig.json

Loading svelte-check in workspace: /Users/mishankov/dev_agents/string-manipulator
Getting Svelte diagnostics...

svelte-check found 0 errors and 0 warnings)

• All linting checks pass (

string-manipulator@0.0.1 lint
prettier --check . && eslint .

Checking formatting...
All matched files use Prettier code style!)

• Manually verified layout changes with browser dev tools at various screen sizes

Code Review Summary

No blockers found. Changes follow CSS best practices:

• Uses standard 768px mobile breakpoint
• Maintains desktop layout unchanged
• Adds to prevent grid overflow issues
• Progressive enhancement approach for mobile