body { margin: 0; font-family: 'Segoe UI', sans-serif; background-color: #1a1a1a; color: #e0e0e0; }

#app { padding: 20px; max-width: 900px; margin: auto;  }

h1 { text-align: center; color: #f0f0f0; }

#chart { margin-top: 40px; width: 100%; height: 340px; background: linear-gradient(to right, #222, #333); border: 1px solid #444; position: relative;}
#controls { margin-top: 20px; text-align: center; }
#controls button { background-color: #444; color: #fff; border: none; padding: 10px 15px; margin: 5px; cursor: pointer; border-radius: 4px; }
#controls button:hover { background-color: #666; }