body { background:#0d1117; color:white; font-family:Arial; margin:0; padding:20px; }
#tabs { margin-bottom:20px; }
button { padding:10px 20px; margin-right:10px; }
.tab { display:none; }
.tab.active { display:block; }
textarea { width:100%; height:200px; background:#161b22; color:white; border:none; padding:10px; }