:root {
  --panel: rgba(17, 26, 45, 0.75);
  --accent: #3f7dff;
}

* { box-sizing: border-box; }
html, body {
  margin: 0;
  width: 100%;
  height: 100%;
  font-family: Inter, system-ui, sans-serif;
  background: #78c6ff;
  overflow: hidden;
}

#game {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  display: block;
}

.panel {
  position: fixed;
  z-index: 5;
  display: flex;
  gap: 0.6rem;
  align-items: center;
  background: var(--panel);
  color: #fff;
  border-radius: 14px;
  padding: 0.55rem 0.75rem;
  backdrop-filter: blur(4px);
}

#hud-top { top: 12px; left: 12px; }
#hud-bottom {
  bottom: 14px;
  left: 50%;
  transform: translateX(-50%);
}

.chip {
  display: flex;
  gap: 0.45rem;
  align-items: center;
  border-radius: 999px;
  padding: 0.3rem 0.6rem;
  background: rgba(255, 255, 255, 0.14);
}

.icon { filter: drop-shadow(0 0 4px rgba(0,0,0,0.2)); }

#hud-right {
  position: fixed;
  right: 12px;
  top: 30%;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  z-index: 5;
}

.tool, #upgradeBtn {
  border: none;
  border-radius: 14px;
  background: linear-gradient(180deg, #5ba1ff, #2d68f5);
  color: #fff;
  padding: 0.65rem 0.8rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 8px 22px rgba(37, 96, 255, 0.3);
}

.tool.active {
  outline: 2px solid #fff;
  transform: scale(1.06);
}

#upgradeBtn:disabled {
  background: #8a95af;
  box-shadow: none;
  cursor: not-allowed;
}