body{margin:0;background:#eef4f1;color:#203029}.practice-app{width:min(820px,calc(100% - 40px));margin:auto;padding:64px 0}.mode-badge{display:inline-block;padding:6px 10px;border-radius:999px;background:#f5c851;font-weight:900}.boundary-note,.control-panel,.trace-panel{padding:16px;border:1px solid #bdc9c2;border-radius:14px;background:white}.boundary-note{border-left:5px solid #b87900}form{display:flex;gap:10px;margin:24px 0}label{display:grid;flex:1;gap:6px}input{padding:12px;border:1px solid #aebdb5;border-radius:9px}button{align-self:end;padding:12px 18px;border:0;border-radius:9px;background:#0c7656;color:white;font:inherit;font-weight:800;cursor:pointer}button:disabled{cursor:not-allowed;opacity:.45}.control-panel,.trace-panel{margin-top:22px}.control-panel h2,.trace-panel h2{margin-top:0}.control-row{display:flex;flex-wrap:wrap;gap:10px}.message-list{display:grid;gap:10px;padding:0;list-style:none}.message-list li{padding:14px;border:1px solid #bdc9c2;border-radius:12px;background:white}#trace-log{max-height:260px;margin:0;padding-left:24px;overflow:auto;font-family:ui-monospace,SFMono-Regular,Menlo,monospace;font-size:.9rem}@media(max-width:600px){form{align-items:stretch;flex-direction:column}.control-row{display:grid}.control-row button{width:100%}}