LibHTML: Respect the system theme

LibHTML will now use the palette colors for the default document background and
the text. As always, a page can override this default styling with CSS if it
really wants a specific color or style.

Fixes https://github.com/SerenityOS/serenity/issues/963

Libraries/LibHTML/DOM/Document.cpp

@@ -1,6 +1,7 @@
 #include <AK/FileSystemPath.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/CTimer.h>
+#include <LibGUI/GApplication.h>
 #include <LibHTML/CSS/StyleResolver.h>
 #include <LibHTML/DOM/Document.h>
 #include <LibHTML/DOM/DocumentType.h>
@@ -116,19 +117,20 @@ void Document::detach_from_frame(Badge<Frame>, Frame&)
     m_frame = nullptr;
 }
 
-Color Document::background_color() const
+Color Document::background_color(const Palette& palette) const
 {
+    auto default_color = palette.base();
     auto* body_element = body();
     if (!body_element)
-        return Color::White;
+        return default_color;
 
     auto* body_layout_node = body_element->layout_node();
     if (!body_layout_node)
-        return Color::White;
+        return default_color;
 
     auto background_color = body_layout_node->style().property(CSS::PropertyID::BackgroundColor);
     if (!background_color.has_value() || !background_color.value()->is_color())
-        return Color::White;
+        return default_color;
 
     return background_color.value()->to_color(*this);
 }

Libraries/LibHTML/DOM/Document.h

@@ -10,6 +10,7 @@
 #include <LibHTML/CSS/StyleSheet.h>
 #include <LibHTML/DOM/ParentNode.h>
 
+class Palette;
 class CTimer;
 class Frame;
 class HTMLBodyElement;
@@ -60,7 +61,7 @@ public:
     Frame* frame() { return m_frame.ptr(); }
     const Frame* frame() const { return m_frame.ptr(); }
 
-    Color background_color() const;
+    Color background_color(const Palette&) const;
     RefPtr<GraphicsBitmap> background_image() const;
 
     Color link_color() const { return m_link_color; }

Libraries/LibHTML/HtmlView.cpp

@@ -38,7 +38,7 @@ HtmlView::HtmlView(GWidget* parent)
     set_frame_shadow(FrameShadow::Sunken);
     set_frame_thickness(2);
     set_should_hide_unnecessary_scrollbars(true);
-    set_background_color(Color::White);
+    set_background_role(ColorRole::Base);
 }
 
 HtmlView::~HtmlView()
@@ -122,7 +122,7 @@ void HtmlView::paint_event(GPaintEvent& event)
         return;
     }
 
-    painter.fill_rect(event.rect(), document()->background_color());
+    painter.fill_rect(event.rect(), document()->background_color(palette()));
 
     if (auto background_bitmap = document()->background_image()) {
         painter.draw_tiled_bitmap(event.rect(), *background_bitmap);

Libraries/LibHTML/Layout/LayoutListItemMarker.cpp

@@ -15,5 +15,6 @@ void LayoutListItemMarker::render(RenderingContext& context)
     Rect bullet_rect { 0, 0, 4, 4 };
     bullet_rect.center_within(enclosing_int_rect(rect()));
     // FIXME: It would be nicer to not have to go via the parent here to get our inherited style.
-    context.painter().fill_rect(bullet_rect, parent()->style().color_or_fallback(CSS::PropertyID::Color, document(), Color::Black));
+    auto color = parent()->style().color_or_fallback(CSS::PropertyID::Color, document(), context.palette().base_text());
+    context.painter().fill_rect(bullet_rect, color);
 }

Libraries/LibHTML/Layout/LayoutText.cpp

@@ -46,7 +46,7 @@ void LayoutText::render_fragment(RenderingContext& context, const LineBoxFragmen
     if (background_color.has_value() && background_color.value()->is_color())
         painter.fill_rect(enclosing_int_rect(fragment.rect()), background_color.value()->to_color(document()));
 
-    auto color = style().color_or_fallback(CSS::PropertyID::Color, document(), Color::Black);
+    auto color = style().color_or_fallback(CSS::PropertyID::Color, document(), context.palette().base_text());
     auto text_decoration = style().string_or_fallback(CSS::PropertyID::TextDecoration, "none");
 
     if (document().inspected_node() == &node())
@@ -146,7 +146,7 @@ void LayoutText::split_into_lines(LayoutBlock& container)
     if (style().string_or_fallback(CSS::PropertyID::WhiteSpace, "normal") == "pre") {
         split_preformatted_into_lines(container);
         return;
-   }
+    }
 
     // Collapse whitespace into single spaces
     auto utf8_view = Utf8View(node().data());