diff -ur mupdf-1.24.9-source.orig/platform/x11/x11_main.c mupdf-1.24.9-source/platform/x11/x11_main.c
--- mupdf-1.24.9-source.orig/platform/x11/x11_main.c	2025-02-28 15:21:40.657163212 +0100
+++ mupdf-1.24.9-source/platform/x11/x11_main.c	2025-02-28 15:22:19.302378030 +0100
@@ -121,6 +121,7 @@
 static Time copytime;
 static char *filename;
 static char message[1024] = "";
+static char *papercolor = 0;
 
 static pdfapp_t gapp;
 static int closing = 0;
@@ -154,6 +155,14 @@
 	}
 }
 
+static int colorasrgb(const char *name, XColor *color) {
+	XColor dummy;
+	if(XAllocNamedColor(xdpy, DefaultColormap(xdpy, xscr), name, color, &dummy))
+		return 1;
+	fprintf(stderr, "mupdf: couldn't allocate color '%s'", name);
+	return 0;
+}
+
 void winerror(pdfapp_t *app, char *msg)
 {
 	fprintf(stderr, "mupdf: error: %s\n", msg);
@@ -248,9 +257,11 @@
 	xcwait = XCreateFontCursor(xdpy, XC_watch);
 	xccaret = XCreateFontCursor(xdpy, XC_xterm);
 
-	xbgcolor.red = 0x7000;
-	xbgcolor.green = 0x7000;
-	xbgcolor.blue = 0x7000;
+	if (!papercolor || !colorasrgb(papercolor, &xbgcolor)) {
+		xbgcolor.red = 0x7000;
+		xbgcolor.green = 0x7000;
+		xbgcolor.blue = 0x7000;
+	}
 
 	XAllocColor(xdpy, DefaultColormap(xdpy, xscr), &xbgcolor);
 
@@ -876,6 +887,7 @@
 	fprintf(stderr, "\t-S -\tfont size for EPUB layout\n");
 	fprintf(stderr, "\t-U -\tuser style sheet for EPUB layout\n");
 	fprintf(stderr, "\t-X\tdisable document styles for EPUB layout\n");
++	fprintf(stderr, "\t-P -\tpaper color\n");
 	exit(1);
 }
 
@@ -907,7 +919,7 @@
 
 	pdfapp_init(ctx, &gapp);
 
-	while ((c = fz_getopt(argc, argv, "Ip:r:A:C:W:H:S:U:Xb:")) != -1)
+	while ((c = fz_getopt(argc, argv, "Ip:r:A:C:W:H:S:U:Xb:P:")) != -1)
 	{
 		switch (c)
 		{
@@ -926,6 +938,7 @@
 		case 'U': gapp.layout_css = fz_optarg; break;
 		case 'X': gapp.layout_use_doc_css = 0; break;
 		case 'b': kbps = fz_atoi(fz_optarg); break;
+ 		case 'P': papercolor = fz_optarg; break;
 		default: usage(argv[0]);
 		}
 	}
Only in mupdf-1.24.9-source/platform/x11: x11_main.c.orig
Only in mupdf-1.24.9-source/platform/x11: x11_main.c.rej