Remove any variables in the optional build variable list that are marked as mandatory by one or more included build system modules in the CORE build system module. Alter DOXYGEN build system module to by default override the Doxygen configuration file stylesheet and replace it with the LUFA Doxygen stylesheet.

LUFA/Build/lufa.core.in

@@ -76,7 +76,7 @@ help: info
 	@echo "                                                                   "
 	@echo "  Optional variables required by the selected build Modules:       "
 	@echo "                                                                   "
-	@echo "    [" $(sort $(LUFA_BUILD_OPTIONAL_VARS)) "]"
+	@echo "    [" $(filter-out $(LUFA_BUILD_MANDATORY_VARS), $(sort $(LUFA_BUILD_OPTIONAL_VARS))) "]"
 	@echo "                                                                   "
 	@echo "==================================================================="
 	@echo "        The LUFA BuildSystem 2.0 - Powered By Unicorns (tm)        "
@@ -92,4 +92,4 @@ list_mandatory:
 	@echo Mandatory Variables for Included Modules: $(sort $(LUFA_BUILD_MANDATORY_VARS))
 	
 list_optional:
-	@echo Optional Variables for Included Modules: $(sort $(LUFA_BUILD_OPTIONAL_VARS))
+	@echo Optional Variables for Included Modules: $(filter-out $(LUFA_BUILD_MANDATORY_VARS), $(sort $(LUFA_BUILD_OPTIONAL_VARS)))

LUFA/Build/lufa.doxygen.in

@@ -8,7 +8,7 @@
 
 LUFA_BUILD_MODULES        += DOXYGEN
 LUFA_BUILD_TARGETS        += doxygen
-LUFA_BUILD_MANDATORY_VARS += 
+LUFA_BUILD_MANDATORY_VARS += LUFA_PATH
 LUFA_BUILD_OPTIONAL_VARS  += DOXYGEN_CONF DOXYGEN_FAIL_ON_WARNING DOXYGEN_OVERRIDE_PARAMS
 
 # -----------------------------------------------------------------------------
@@ -24,7 +24,7 @@ LUFA_BUILD_OPTIONAL_VARS  += DOXYGEN_CONF DOXYGEN_FAIL_ON_WARNING DOXYGEN_OVERRI
 #
 # MANDATORY PARAMETERS:
 #
-#    (None)
+#    LUFA_PATH                 - Path to the LUFA library core
 #
 # OPTIONAL PARAMETERS:
 #
@@ -35,16 +35,19 @@ LUFA_BUILD_OPTIONAL_VARS  += DOXYGEN_CONF DOXYGEN_FAIL_ON_WARNING DOXYGEN_OVERRI
 #                                configuration file
 # -----------------------------------------------------------------------------
 
+# Sanity-check values of mandatory user-supplied variables
+LUFA_PATH               ?= $(error Makefile LUFA_PATH value not set.)
+
 # Default values of optionally user-supplied variables
 DOXYGEN_CONF            ?= Doxygen.conf
 DOXYGEN_FAIL_ON_WARNING ?= Y
-DOXYGEN_OVERRIDE_PARAMS ?= QUIET=YES
+DOXYGEN_OVERRIDE_PARAMS ?= QUIET=YES HTML_STYLESHEET=$(patsubst %/,%,$(LUFA_PATH))/DoxygenPages/Style/Style.css
 
 # Output Messages
 MSG_DOXYGEN_CMD          = ' [DOXYGEN] :'
 
 # Determine Doxygen invocation command
-BASE_DOXYGEN_CMD = ( cat Doxygen.conf ; $(DOXYGEN_OVERRIDE_PARAMS:%=echo "%") ) | doxygen -
+BASE_DOXYGEN_CMD = ( cat Doxygen.conf $(DOXYGEN_OVERRIDE_PARAMS:%=; echo "%") ) | doxygen -
 ifeq ($(DOXYGEN_FAIL_ON_WARNING), Y)
    DOXYGEN_CMD = if ( $(BASE_DOXYGEN_CMD) 2>&1 | grep -v "warning: ignoring unsupported tag" ;); then exit 1; fi;
 else