[MUI] <Select /> 기본 스타일링

const Container = styled(Select)`
  width: 100%;
  padding: 10px 12px;
  font-size: 16px;
  border-radius: 6px;
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
  background-color: white;

  & .MuiSelect-select {
    padding: 0px;
  }

  & input {
    border: 0px;
  }

  & fieldset {
    border: 1px solid #ccc;
  }

  &:hover fieldset {
    border-color: #ccc !important;
  }

  /* Select가 선택(포커스) 되었을 때 */
  &.Mui-focused fieldset {
    border-color: #007bff !important;
    border-width: 1px !important; /* ✅ 두께를 고정 */
  }
`;