Merge #553: Change address / amount error background

fe7c81e qt: change QLineEdit error background (w0xlt)

Pull request description:

  This PR proposes a small change in QLineEdit when there is an error in the input.

  master |
  --- |
  ![image](https://user-images.githubusercontent.com/94266259/154762427-b816267e-ec70-4a8f-a7fb-1317ebacf1a4.png)

  PR |
  --- |
  ![image](https://user-images.githubusercontent.com/94266259/154761933-15eb3d81-ca81-4498-b8ec-cf1139ae2f8a.png) |

  This also shows good results when combined with other open PRs.

  #537 |
  --- |
  ![image](https://user-images.githubusercontent.com/94266259/154763411-6266a283-2d8a-4365-b3f2-a5cb545e773e.png)

  #533 |
  --- |
  ![image](https://user-images.githubusercontent.com/94266259/154765638-f38b13d6-a4f8-4b46-a470-f882668239f3.png) |

ACKs for top commit:
  GBKS:
    ACK fe7c81e
  jarolrod:
    ACK fe7c81e
  shaavan:
    ACK fe7c81e

Tree-SHA512: eccc53f42d11291944ccb96efdbe460cb10af857f1d4fa9b5348ddcb0796c82faf1cdad9040aae7a25c5d8f4007d6284eba868d7af14acf56280f6acae170b91

Author: hebasto

src/qt/guiconstants.h

@@ -25,7 +25,7 @@ static const int STATUSBAR_ICONSIZE = 16;
 static const bool DEFAULT_SPLASHSCREEN = true;
 
 /* Invalid field background style */
-#define STYLE_INVALID "background:#FF8080"
+#define STYLE_INVALID "border: 3px solid #FF8080"
 
 /* Transaction list -- unconfirmed transaction */
 #define COLOR_UNCONFIRMED QColor(128, 128, 128)