:root {
  --green: #28a745;
  --bg1: #e9f7ef;
  --bg2: #d4efdf;
}

body {
  background: linear-gradient(135deg, var(--bg1), var(--bg2));
  font-family: 'Poppins', sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.card {
  border: none;
  border-radius: 15px;
  transition: 0.25s ease;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 6px 20px rgba(0, 128, 0, 0.12);
}

#carbonResult {
  color: var(--green);
  font-size: 1.6rem;
}

#ecoTip {
  font-style: italic;
  margin-top: 10px;
}

#leaderboard li {
  border-radius: 10px;
  margin: 6px 0;
  background-color: #f8f9fa;
}

button:active {
  transform: scale(0.98);
}

canvas {
  background: #ffffff;
  border-radius: 12px;
  padding: 10px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.06);
  width: 100% !important;
  height: auto !important;
}

footer {
  margin-top: auto;
}

/* Responsive Tweaks */
@media (max-width: 767px) {
  #carbonResult {
    font-size: 1.2rem;
  }
  canvas {
    max-width: 100%;
    height: 250px !important;
  }
}