themes: improve themes.

- Indent all rules in Light theme with the same number of spaces for
  style consistency.
- When GIMP was set in "Prefer dark variant", spin buttons and other
  entries had too dark borders. Fix this.
- Fix the spinbutton entry's border radius which was at 0, but since the
  buttons of the spin button are themselves rounded, it looks weird only
  on the top and bottom left corners. So apply a 3px radius. I did this
  in the System theme.

themes/Light/gimp.css

@@ -17,19 +17,19 @@
 }
 
 #image-menubar, GtkImageMenuItem {
-   background-color: rgb(235,235,235);
-   color: black;
+  background-color: rgb(235,235,235);
+  color: black;
 }
 
 /* TreeViews, e.g. in a file picker or the Prefs dialog */
 .view {
-   background-color: rgb(250,250,250);
-   color: black;
+  background-color: rgb(250,250,250);
+  color: black;
 }
 
 .view:selected {
-   background-color: rgb(220,220,220);
-   color: black;
+  background-color: rgb(220,220,220);
+  color: black;
 }
 
 /* The main image window before it has an image in it,
@@ -50,8 +50,8 @@ GimpDisplayShell, GimpDock, .dialog-action-box, .dialog-vbox {
 
 /* GtkTextView */
 textview text, textview {
-   background-color: rgba (184, 184, 184, 0.5);
-   color: black;
+  background-color: rgba (184, 184, 184, 0.5);
+  color: black;
 }
 /* End GtkTextView */
 
@@ -247,10 +247,15 @@ button:disabled {
  * so they're not overridden.
  */
 
+spinbutton, entry {
+  /* Borders are a bit darker, but not too dark. */
+  border-color: rgb(200,200,200);
+}
+
 GimpSpinScale entry progress {
-    background-color: rgb(220,220,220);
-    border-width:     0px;
-    border-radius:    3px;
+  background-color: rgb(220,220,220);
+  border-width:     0px;
+  border-radius:    3px;
 }
 
 /* Checkboxes */
@@ -279,7 +284,7 @@ tooltip {
 
 /* The border around a tooltip */
 .background {
-   background-color: rgb(220,220,220);
+  background-color: rgb(220,220,220);
 }
 
 /* The border around a frame */
@@ -289,8 +294,8 @@ border {
 
 /* For dropdown menus (e.g. "px" when creating a new image */
 #gtk-combobox-popup-menu {
-   background-color: rgb(235,235,235);
-   color: black;
+  background-color: rgb(235,235,235);
+  color: black;
 }
 
 /* Top menu items  */
@@ -325,7 +330,7 @@ menu {
  * colors when highlighted
  */
 menu box {
-   background-color: transparent;
+  background-color: transparent;
 }
 
 /* Sidebar in File > Open */
@@ -359,13 +364,13 @@ headerbar:backdrop {
 /* GtkListBox widgets */
 
 list {
-   background-color: rgb(235,235,235);
+  background-color: rgb(235,235,235);
 }
 
 /* GtkSwitch buttons */
 
 switch {
-   background-color: rgb(235,235,235);
+  background-color: rgb(235,235,235);
 }
 
 /* The switch button is quite hard to understand without color IMO. So
@@ -373,5 +378,5 @@ switch {
  * state, even though this is globally a neutral gray theme.
  */
 switch:checked {
-    background-color: rgb(200,200,255);
+  background-color: rgb(200,200,255);
 }

themes/System/gimp.css

@@ -117,6 +117,10 @@ GimpRuler {
     font-size: smaller;
 }
 
+spinbutton entry {
+    border-radius: 3px;
+}
+
 GimpSpinScale entry {
     /* Important: prevent overhigh spin scale */
     min-height: 16px;