message: [Header] fix baseline-aligning firefox bug
diff: .Header--ios.Header--mode-primary .Header__content {
  font-size: 17px;
  line-height: 22px;
  - padding: 13px 0 9px;
  + /* https://github.com/VKCOM/VKUI/issues/738 */
  + margin: 13px 0 9px;
  }
  .Header--ios.Header--mode-secondary .Header__content {
  - padding: 14px 0 10px;
  + /* https://github.com/VKCOM/VKUI/issues/738 */
  + margin: 14px 0 10px;
  font-size: 13px;
  line-height: 16px;
  }
  .Header--android.Header--mode-primary .Header__content,
  .Header--vkcom.Header--mode-primary .Header__content {
  - padding: 15px 0 9px;
  + /* https://github.com/VKCOM/VKUI/issues/738 */
  + margin: 15px 0 9px;
  font-size: 16px;
  line-height: 20px;
  }
  .Header--android.Header--mode-secondary .Header__content,
  .Header--vkcom.Header--mode-secondary .Header__content {
  - padding: 15px 0 9px;
  + /* https://github.com/VKCOM/VKUI/issues/738 */
  + margin: 15px 0 9px;
  font-size: 13px;
  line-height: 16px;
  }
  