*, *::before, *::after {
  box-sizing: border-box;
}

body {
  font-family: system-ui, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  margin: 0;
  background: #1e293b;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

.battery-wrapper {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.battery-terminal {
  width: 40px;
  height: 16px;
  background: #475569;
  border-radius: 6px 6px 0 0;
}

.battery-body {
  position: relative;
  width: 140px;
  height: 260px;
  border: 4px solid #475569;
  border-radius: 16px;
  background: #0f172a;
  overflow: hidden;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.4);
  display: flex;
  justify-content: center;
  align-items: center;
}

.charge-liquid {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 0%;
  background: #ef4444;
  /* Animate height and color securely over 8 seconds */
  animation: fill-battery 8s ease-in-out infinite;
}

.charge-liquid::before {
  content: "";
  position: absolute;
  top: -10px;
  left: -50%;
  width: 200%;
  height: 20px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  animation: wave-horizontal 2s infinite linear;
}

@keyframes fill-battery {
  0% { height: 5%; background: #ef4444; box-shadow: 0 0 20px #ef4444; }
  30% { background: #f59e0b; box-shadow: 0 0 20px #f59e0b; }
  70% { background: #10b981; box-shadow: 0 0 20px #10b981; }
  100% { height: 95%; background: #10b981; box-shadow: 0 0 30px #10b981; }
}

@keyframes wave-horizontal {
  0% { transform: translateX(0); }
  100% { transform: translateX(25%); }
}

.charge-text {
  position: relative;
  z-index: 10;
  color: #ffffff;
  font-weight: 800;
  letter-spacing: 2px;
  text-transform: uppercase;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.8);
}