:root{font-family:Hiragino Sans,Noto Sans JP,sans-serif;line-height:1.5;color:#111827;background:linear-gradient(135deg,#f7f7f7,#eef6ff)}*{box-sizing:border-box}body{margin:0;min-height:100vh}.app{max-width:760px;margin:0 auto;padding:40px 16px}.card{border:1px solid #d1d5db;border-radius:12px;padding:16px;background:#fff}.error{color:#b91c1c}pre{background:#f3f4f6;padding:12px;border-radius:8px;overflow-x:auto}