.base-converter {
  padding: 50px 20px;
  background: #121212;
  color: #f0f0f0;
  font-family: 'Segoe UI', sans-serif;
  max-width: 600px;
  margin: 0 auto;
  border-radius: 12px;
  box-shadow: 0 0 16px rgba(0, 0, 0, 0.4);
}

.tool-header {
  text-align: center;
  margin-bottom: 30px;
}

.tool-header h2 {
  font-size: 30px;
  color: #90caf9;
  margin-bottom: 8px;
}

.tool-header p {
  font-size: 16px;
  color: #ccc;
}

.converter-box {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.form-group label {
  font-weight: 600;
  color: #ddd;
  margin-bottom: 6px;
  display: block;
}

.form-group input,
.form-group select {
  padding: 10px 14px;
  font-size: 16px;
  width: 100%;
  border-radius: 8px;
  border: 1px solid #444;
  background: #1e1e1e;
  color: #fff;
}

.form-group input::placeholder {
  color: #aaa;
}

button#convertBtn {
  padding: 12px;
  font-size: 16px;
  background: #2196f3;
  color: #fff;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 600;
  transition: background 0.3s ease;
}

button#convertBtn:hover {
  background: #1976d2;
}

.output-group {
  background: #1e1e1e;
  padding: 14px;
  border-radius: 8px;
  border: 1px dashed #2196f3;
  font-size: 18px;
  font-weight: bold;
  color: #ffffff;
  text-align: center;
}

/* Responsive */
@media (max-width: 500px) {
  .base-converter {
    padding: 30px 15px;
  }

  .tool-header h2 {
    font-size: 24px;
  }

  .tool-header p {
    font-size: 14px;
  }

  button#convertBtn {
    font-size: 14px;
  }

  .output-group {
    font-size: 16px;
  }
}