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

:root {
  --bg: #0e141b;
  --panel: rgba(18, 26, 36, 0.85);
  --accent: #4fd1c5;
  --accent-dim: #2c7a75;
  --gold: #f6c453;
  --danger: #f2545b;
  --text: #dbe4ee;
}

html,
body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", system-ui, sans-serif;
  user-select: none;
}

#game {
  position: fixed;
  inset: 0;
}

#hud {
  position: fixed;
  top: 16px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 28px;
  padding: 12px 26px;
  background: var(--panel);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 14px;
  backdrop-filter: blur(6px);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.4);
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-width: 60px;
}

.stat .label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 1px;
  opacity: 0.6;
}

.stat span:last-child {
  font-size: 22px;
  font-weight: 700;
}

#lives {
  color: var(--danger);
}

#gold {
  color: var(--gold);
}

#shop {
  position: fixed;
  right: 16px;
  top: 50%;
  transform: translateY(-50%);
  width: 220px;
  padding: 18px;
  background: var(--panel);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 14px;
  backdrop-filter: blur(6px);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.4);
}

.shop-title {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 2px;
  opacity: 0.6;
  margin-bottom: 12px;
}

.tower-btn {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px;
  margin-bottom: 8px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.03);
  color: var(--text);
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s;
  text-align: left;
}

.tower-btn:hover {
  background: rgba(255, 255, 255, 0.07);
}

.tower-btn.selected {
  border-color: var(--accent);
  background: rgba(79, 209, 197, 0.12);
}

.tower-btn .swatch {
  width: 20px;
  height: 20px;
  border-radius: 5px;
  flex-shrink: 0;
}

.tower-btn .info {
  flex: 1;
}

.tower-btn .name {
  font-size: 14px;
  font-weight: 600;
}

.tower-btn .cost {
  font-size: 12px;
  color: var(--gold);
}

.tower-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.tower-btn.dim {
  opacity: 0.45;
}

#base-card .tower-btn {
  cursor: default;
}

#upgrade-panel {
  position: fixed;
  left: 16px;
  top: 50%;
  transform: translateY(-50%);
  width: 220px;
  padding: 18px;
  background: var(--panel);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 14px;
  backdrop-filter: blur(6px);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.4);
}

#upgrade-panel.hidden {
  display: none;
}

#tower-status {
  margin-bottom: 14px;
  padding-bottom: 12px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.status-row {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  padding: 3px 0;
}

.status-row span:first-child {
  opacity: 0.55;
}

.status-row span:last-child {
  font-weight: 600;
}

#upgrade-close {
  width: 100%;
  margin-top: 10px;
  padding: 9px;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 10px;
  background: transparent;
  color: var(--text);
  font-size: 13px;
  cursor: pointer;
}

#upgrade-close:hover {
  background: rgba(255, 255, 255, 0.06);
}

#start-wave {
  width: 100%;
  margin-top: 8px;
  padding: 12px;
  border: none;
  border-radius: 10px;
  background: var(--accent);
  color: #05201d;
  font-size: 15px;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.15s;
}

#start-wave:hover {
  background: #6ee7db;
}

#start-wave:disabled {
  background: var(--accent-dim);
  cursor: default;
  opacity: 0.7;
}

.hint {
  margin-top: 14px;
  font-size: 11px;
  line-height: 1.5;
  opacity: 0.5;
}

#overlay {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(6, 10, 14, 0.75);
  backdrop-filter: blur(4px);
  z-index: 20;
}

#overlay.hidden {
  display: none;
}

.overlay-card {
  text-align: center;
  padding: 40px 50px;
  background: var(--panel);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 18px;
}

.overlay-card h1 {
  font-size: 36px;
  margin-bottom: 12px;
}

.overlay-card p {
  opacity: 0.7;
  margin-bottom: 24px;
}

#overlay-restart {
  padding: 12px 28px;
  border: none;
  border-radius: 10px;
  background: var(--accent);
  color: #05201d;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
}