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Updated: 2026年5月31日
Border Radius
Original task (JA): 角丸
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Conclusion
Border Radius — free browser-based HTML/CSS/JS practice
Why it matters in real projects
border-radiusで角を丸くできます。 Similar patterns appear daily in code review and production UI work.Step-by-step workflow
1. Read the guide and understand the goal of "Border Radius" 2. Review the HTML/CSS/JS editor pane and start from the starter code 3. Open hints if stuck; compare your diff with the sample solution 4. Click Run and inspect preview/console output 5. Auto-check looks for output containing: border-radius, 8px. 6. After success, continue with adjacent exercises in the same categoryCore concept explained
border-radiusで角を丸くできます。Technical focus
Key HTML elements in this task: div, style.Hint before you peek at the solution
border-radius: 8px;Sample solution walkthrough
The solution uses HTML tags such as div, style. Check nesting and closing tags. CSS properties include border-radius, border. Watch selector spelling and specificity. Explanation: border-radiusで角を丸くできます。 Hint recap: border-radius: 8px;Solution code
📝 Sample code
<div>ボックス</div>
<style>div { border-radius: 8px; border: 1px solid #ccc; }</style>Common mistakes for this exact task
・Skipping the hint: border-radius: 8px;Troubleshooting
Q: Preview does not change after Run A: Ensure you edited the HTML/CSS/JS pane and clicked Run. Q: Looks correct but check fails A: Auto-check looks for output containing: border-radius, 8px. Look for typos, full-width spaces, or unclosed tags. Q: Console shows errors A: Open DevTools Console and fix bracket/quote mismatches at the reported line. Q: Hard to type on mobile A: Use landscape mode or continue on desktop—the same URL keeps progress in localStorage.Interview / portfolio tips
・Explain the techniques in "Border Radius" in your own words within 30 seconds ・Practice walking through each line of the sample solution on a whiteboard ・Be ready to discuss tags: div, style ・Discuss CSS properties: border-radius, border ・Prepare one alternative approach and why you chose this oneWhat to do after you pass
Move to the next exercise in the css-basic track, then continue the learning roadmap at /en/learning/css-basic/.Keywords
Free hands-on exercise covering 角丸, css-basic, 入門, div, style, border-radius, border, border radius—search-friendly guide for Border Radius.🧪 Try it here — safe to break things
Use the editor below to write code and preview instantly.
Jump to editor■ Exercise task
divの角を8px丸くしてください。
Hint if stuck
border-radius: 8px;