Import upstream Diehard4 by obscurant

Verbatim contents of the upstream GitHub archive (Diehard4-master.zip,
commit 254ee204deebc64793123a9643c85b7d113c6c22, files dated 2019-05-21).

Imported unmodified so that every change in this fork is visible as a diff
against the original, which is what GPL-3.0 section 5(a) is asking for.
All code in this commit is obscurant's work, not mine.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

gtk-3.0/unity-greeter.css

@@ -0,0 +1,67 @@
+.lightdm.menu {
+    background-image: none;
+    background-color: alpha (black, 0.6);
+    border-color: alpha (white, 0.2);
+    border-radius: 4px;
+    padding: 1px;
+
+    color: white;
+}
+
+.lightdm-combo .menu {
+    background-color: shade (@dark_bg_color, 1.08);
+    border-radius: 0px;
+    padding: 0px;
+    color: white;
+}
+
+.lightdm.menu .menuitem *,
+.lightdm.menu .menuitem.check:active,
+.lightdm.menu .menuitem.radio:active {
+    color: white;
+}
+
+.lightdm.menubar {
+    background-image: none;
+    background-color: alpha (black, 0.5);
+}
+
+.lightdm-combo.combobox-entry .button,
+.lightdm-combo .cell,
+.lightdm-combo .button,
+.lightdm-combo .entry,
+.lightdm.button,
+.lightdm.entry {
+    background-image: none;
+    background-color: alpha (black, 0.3);
+    border-color: alpha (white, 0.6);
+    border-radius: 5px;
+    padding: 7px;
+    color: white;
+    text-shadow: none;
+}
+
+.lightdm.button,
+.lightdm.button:hover,
+.lightdm.button:active,
+.lightdm.button:active:focused,
+.lightdm.entry,
+.lightdm.entry:hover,
+.lightdm.entry:active,
+.lightdm.entry:active:focused {
+    background-image: none;
+    border-image: none;
+}
+
+.lightdm.button:focused,
+.lightdm.entry:focused {
+    -unico-focus-border-color: alpha (white, 0.9);
+    border-color: alpha (white, 0.9);
+    border-width: 1px;
+    border-style: solid;
+    color: white;
+}
+
+.lightdm.entry:selected {
+    background-color: alpha (white, 0.2);
+}