body {
  margin: 0;
  padding: 0;
  font-family: 'Segoe UI', sans-serif;
  background: #121212;
  color: #ffffff;
}
.layout-container {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  padding: 20px;
}
.converter-box, .chart-box {
  background: #1e1e1e;
  border-radius: 12px;
  margin: 10px;
  padding: 20px;
  flex: 1 1 300px;
  max-width: 600px;
}
.converter-box input, select {
  width: 100%;
  padding: 10px;
  margin: 5px 0 15px;
  background: #2c2c2c;
  border: none;
  border-radius: 6px;
  color: #ffffff;
}
.chart-box canvas {
  width: 100%;
  height: 300px;
}
#chartButtons {
  text-align: center;
  margin-bottom: 10px;
}
#chartButtons button {
  background: #333;
  color: #fff;
  margin: 3px;
  border: none;
  padding: 8px 14px;
  border-radius: 6px;
  cursor: pointer;
}
#chartButtons button:hover {
  background: #555;
}
footer {
  text-align: center;
  padding: 20px;
  color: #aaa;
}
footer a {
  color: orange;
  text-decoration: none;
}
#scrollToTopBtn {
  position: fixed;
  bottom: 20px;
  right: 20px;
  display: none;
  background: #444;
  color: white;
  border: none;
  border-radius: 50%;
  font-size: 24px;
  padding: 8px 12px;
  cursor: pointer;
}
.error-box {
  background-color: #ff000033;
  padding: 10px;
  border-radius: 6px;
  color: #ff6666;
}