body{ font-family: system-ui,Segoe UI,Roboto,Arial; background:#f7fafc; color:#111; margin:0; padding:20px }
.container{ max-width:900px; margin:0 auto; background:#fff; padding:20px; border-radius:8px; box-shadow:0 2px 10px rgba(0,0,0,0.06)}
textarea{ width:100%; font-family:monospace; }
pre{ background:#0f172a; color:#dbeafe; padding:12px; border-radius:6px; overflow:auto }
.controls{ margin-top:8px }
button{ padding:8px 12px; margin-right:8px }
input, textarea{ box-sizing:border-box }