Bug 559564 - Darken images when help is shown in dark mode

Change-Id: If3c957986a3f2ef33814a466413680967dd02416
diff --git a/org.eclipse.help.base/doc/book.css b/org.eclipse.help.base/doc/book.css
index 5838ae7..a10f6d7 100644
--- a/org.eclipse.help.base/doc/book.css
+++ b/org.eclipse.help.base/doc/book.css
@@ -49,4 +49,13 @@
 	body, h1, h2, h3, h4, h5, h6, p, table, td, caption, th, ul, ol, dl, li, dd, dt {
 		color: #f0f0f0;
 	}
+	
+	/* darken images to add some comfort while reading in dark theme */
+	img {
+		opacity: .75;
+		transition: opacity .5s ease-in-out;
+	}
+	img:hover {
+		opacity: 1;
+	}
 }
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diff --git a/org.eclipse.help.base/doc/darkTheme.css b/org.eclipse.help.base/doc/darkTheme.css
index 38dfc45..383493c 100644
--- a/org.eclipse.help.base/doc/darkTheme.css
+++ b/org.eclipse.help.base/doc/darkTheme.css
@@ -14,4 +14,13 @@
 	a.nolink:visited {
 		color:#ffffff;
 	}
+	
+	/* darken images to add some comfort while reading in dark theme */
+	img {
+		opacity: .75;
+		transition: opacity .5s ease-in-out;
+	}
+	img:hover {
+		opacity: 1;
+	}
 }
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diff --git a/org.eclipse.help.webapp/advanced/darkTheme.css b/org.eclipse.help.webapp/advanced/darkTheme.css
index 5d70287..b48d821 100644
--- a/org.eclipse.help.webapp/advanced/darkTheme.css
+++ b/org.eclipse.help.webapp/advanced/darkTheme.css
@@ -44,4 +44,13 @@
 	.button a, .buttonMenu a { 
 		border:1px solid #3d3d3d;;
 	}
+	
+	/* darken images to add some comfort while reading in dark theme */
+	img {
+		opacity: .75;
+		transition: opacity .5s ease-in-out;
+	}
+	img:hover {
+		opacity: 1;
+	}
 }
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