* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  width: 100vw;
  height: 100vh;
  background-color: #0f172a;
  /* Subtle dark grid background */
  background-image: 
    linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
  background-size: 40px 40px;
  overflow: hidden;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  position: relative;
}

/* On-screen instruction label */
.instructions {
  position: absolute;
  top: 24px;
  left: 50%;
  transform: translateX(-50%);
  color: #64748b;
  font-size: 0.95rem;
  letter-spacing: 0.5px;
  user-select: none;
  pointer-events: none;
}

.instructions span {
  color: #38bdf8;
  font-weight: 600;
  background: rgba(56, 189, 248, 0.1);
  padding: 3px 8px;
  border-radius: 6px;
  border: 1px solid rgba(56, 189, 248, 0.2);
}

/* The movable element */
#mybox {
  position: absolute;
  width: 90px;
  height: 90px;
  background: linear-gradient(135deg, #6366f1, #a855f7);
  border-radius: 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.2rem;
  user-select: none;
  border: 1px solid rgba(255, 255, 255, 0.15);
  box-shadow: 0 10px 25px -5px rgba(99, 102, 241, 0.4),
              0 8px 10px -6px rgba(99, 102, 241, 0.2);
  /* Smooth movement */
  transition: top 0.08s ease-out, left 0.08s ease-out, background-color 0.2s ease, transform 0.15s ease;
}

#mybox:active {
  transform: scale(0.95);
}