:root {
  --bg: #0a0a0f; --surface: #111122;
  --cyan: #00f0ff; --magenta: #ff00ff;
  --green: #00ff41; --red: #ff3344; --amber: #ffaa00;
  --font: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Helvetica Neue', sans-serif;
  --mono: 'SF Mono', 'Menlo', 'Courier New', monospace;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  background: var(--bg); color: var(--cyan);
  font-family: var(--font);
  overflow: hidden; touch-action: manipulation;
  user-select: none; -webkit-user-select: none;
  -webkit-tap-highlight-color: transparent;
}
#game-container { position: relative; width: 100vw; height: 100dvh; }
#game-canvas { display: block; width: 100%; height: 100%; }
#hud-overlay {
  position: absolute; top: 0; left: 0; right: 0; bottom: 0;
  pointer-events: none; display: flex; flex-direction: column;
  justify-content: space-between;
}

/* Top status */
#hud-top {
  display: flex; justify-content: space-around; padding: 10px 4px;
  background: linear-gradient(180deg, rgba(10,10,15,0.98) 0%, rgba(10,10,15,0.7) 100%);
  border-bottom: 1px solid rgba(0,240,255,0.3);
  font-size: 14px; font-weight: 600; pointer-events: auto;
  font-family: var(--mono);
}

/* Center message */
#center-msg {
  position: absolute; top: 14%; left: 50%; transform: translateX(-50%);
  color: var(--cyan); font-size: 15px; text-align: center;
  pointer-events: none; opacity: 0.8;
  text-shadow: 0 0 8px var(--cyan);
  font-weight: 500; max-width: 90vw;
}

/* Bottom panel */
#hud-bottom {
  display: flex; flex-direction: column; gap: 6px; padding: 8px 8px 12px;
  background: linear-gradient(0deg, rgba(10,10,15,0.98) 0%, rgba(10,10,15,0.8) 100%);
  border-top: 1px solid rgba(0,240,255,0.3); pointer-events: auto;
}

#phase-indicator {
  text-align: center; font-size: 12px; color: var(--green);
  font-weight: 500; letter-spacing: 1px;
}

/* Tower buttons - 3 columns */
#tower-panel {
  display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 6px;
}
.tower-btn {
  background: var(--surface); color: var(--cyan);
  border: 1.5px solid rgba(0,240,255,0.3);
  padding: 10px 4px; cursor: pointer; min-height: 56px;
  font-family: var(--font); border-radius: 6px;
  display: flex; flex-direction: column; align-items: center;
  justify-content: center; gap: 1px;
  transition: all 0.15s;
}
.tower-btn .tower-icon {
  font-family: var(--mono); font-size: 16px; font-weight: 700;
  color: var(--cyan);
}
.tower-btn .tower-label { font-size: 14px; font-weight: 600; }
.tower-btn .tower-cost { font-size: 11px; opacity: 0.6; }
.tower-btn.active {
  background: var(--cyan); color: var(--bg); border-color: var(--cyan);
  box-shadow: 0 0 24px rgba(0,240,255,0.5);
}
.tower-btn.active .tower-icon,
.tower-btn.active .tower-label,
.tower-btn.active .tower-cost { color: var(--bg); }
.tower-btn:active { transform: scale(0.95); }

/* Action row */
#action-row { display: flex; gap: 6px; }
#sell-btn, #market-btn {
  flex: 1; background: var(--surface); color: #aaa;
  border: 1px solid rgba(255,255,255,0.15); padding: 10px;
  font-family: var(--font); font-size: 14px; cursor: pointer;
  min-height: 42px; border-radius: 6px; font-weight: 500;
}
#sell-btn.active { background: var(--red); color: #fff; border-color: var(--red); box-shadow: 0 0 16px rgba(255,51,68,0.4); }
#sell-btn:active, #market-btn:active { transform: scale(0.96); }

/* Start wave */
#start-wave-btn {
  background: var(--magenta); color: #fff; border: none;
  padding: 14px; font-family: var(--font); font-size: 18px;
  font-weight: 700; cursor: pointer; min-height: 52px;
  width: 100%; border-radius: 8px;
  text-transform: uppercase; letter-spacing: 3px;
  box-shadow: 0 0 32px rgba(255,0,255,0.35);
  transition: all 0.15s;
}
#start-wave-btn:active { transform: scale(0.97); }

/* Tutorial */
#tutorial-overlay {
  position: absolute; top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(5,5,15,0.96); display: flex;
  flex-direction: column; justify-content: center; align-items: center;
  gap: 20px; pointer-events: auto; z-index: 30; padding: 24px;
}
#tutorial-overlay.hidden { display: none; }
#tutorial-overlay h2 {
  color: var(--cyan); font-size: 28px; font-weight: 800;
  text-shadow: 0 0 20px var(--cyan); letter-spacing: 4px;
}
.tutorial-steps { display: flex; flex-direction: column; gap: 10px; }
.step {
  color: #ddd; font-size: 15px; display: flex; align-items: center;
  gap: 10px; line-height: 1.5;
}
.step-num {
  display: inline-flex; width: 24px; height: 24px; min-width: 24px;
  background: var(--cyan); color: var(--bg); border-radius: 50%;
  align-items: center; justify-content: center; font-size: 13px;
  font-weight: 700;
}
.tower-intro { display: flex; flex-direction: column; gap: 6px; margin-top: 4px; }
.tower-tip { color: #aaa; font-size: 13px; display: flex; align-items: center; gap: 6px; }
.dot { width: 8px; height: 8px; border-radius: 50%; display: inline-block; }
#tutorial-start-btn {
  background: var(--magenta); color: #fff; border: none;
  padding: 16px 48px; font-family: var(--font); font-size: 18px;
  font-weight: 700; cursor: pointer; min-height: 52px; border-radius: 8px;
  box-shadow: 0 0 30px rgba(255,0,255,0.4); letter-spacing: 3px;
}

/* Game over */
#game-over-screen {
  position: absolute; top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(5,5,15,0.95); display: flex;
  flex-direction: column; justify-content: center; align-items: center;
  gap: 20px; pointer-events: auto; z-index: 20;
}
#game-over-screen.hidden { display: none; }
#game-over-screen h1 { color: var(--red); font-size: 28px; font-weight: 800; }
#game-over-screen p { color: var(--cyan); font-size: 16px; font-family: var(--mono); }
#restart-btn {
  background: var(--cyan); color: var(--bg); border: none;
  padding: 14px 36px; font-family: var(--font); font-size: 18px;
  font-weight: 700; cursor: pointer; min-height: 50px; border-radius: 8px;
  letter-spacing: 2px;
}

/* Upgrade */
#upgrade-screen {
  position: absolute; top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(5,5,15,0.95); display: flex;
  flex-direction: column; justify-content: center; align-items: center;
  gap: 14px; pointer-events: auto; z-index: 25;
}
#upgrade-screen.hidden { display: none; }
#upgrade-screen h2 { color: var(--green); font-size: 22px; font-weight: 700; }
#upgrade-options { display: flex; flex-direction: column; gap: 10px; width: 88%; max-width: 340px; }
.upgrade-option {
  background: var(--surface); color: var(--cyan); border: 1.5px solid rgba(0,240,255,0.3);
  padding: 13px; font-family: var(--font); font-size: 14px; cursor: pointer;
  min-height: 48px; border-radius: 6px; font-weight: 600;
}
.upgrade-option:disabled { opacity: 0.25; }
#close-upgrade-btn {
  background: var(--surface); color: var(--cyan); border: 1.5px solid rgba(0,240,255,0.3);
  padding: 12px 28px; font-family: var(--font); font-size: 16px;
  cursor: pointer; border-radius: 6px; font-weight: 600;
}

/* Market */
#market-panel {
  position: absolute; top: 50%; left: 50%; transform: translate(-50%,-50%);
  background: var(--surface); border: 2px solid var(--amber);
  display: flex; flex-direction: column; gap: 10px; padding: 20px;
  pointer-events: auto; z-index: 20; border-radius: 8px;
  min-width: 280px; align-items: center;
}
#market-panel.hidden { display: none; }
#buy-frag-btn, #sell-frag-btn {
  background: var(--bg); color: var(--amber); border: 1.5px solid var(--amber);
  padding: 12px; font-family: var(--font); font-size: 15px; cursor: pointer;
  min-height: 46px; width: 100%; border-radius: 6px; font-weight: 600;
}
#market-msg { color: var(--green); font-size: 13px; text-align: center; min-height: 18px; font-weight: 500; }
#market-close-btn { color: var(--cyan); font-size: 14px; cursor: pointer; }