diff --git a/core/modules/block/block.admin.css b/core/modules/block/block.admin.css
index 214c8a2..6d50fd6 100644
--- a/core/modules/block/block.admin.css
+++ b/core/modules/block/block.admin.css
@@ -18,7 +18,7 @@
 a.block-demo-backlink,
 a.block-demo-backlink:link,
 a.block-demo-backlink:visited {
-  background-color: #B4D7F0;
+  background-color: #b4d7f0;
   -moz-border-radius: 0 0 10px 10px;
   -webkit-border-radius: 0 0 10px 10px;
   border-radius: 0 0 10px 10px;
diff --git a/core/modules/dashboard/dashboard.css b/core/modules/dashboard/dashboard.css
index 9996ba9..7d6be64 100644
--- a/core/modules/dashboard/dashboard.css
+++ b/core/modules/dashboard/dashboard.css
@@ -27,7 +27,7 @@
 }
 #dashboard #disabled-blocks .block,
 #dashboard .block-placeholder {
-  background: #E2E1DC;
+  background: #e2e1dc;
   -moz-border-radius: 4px;
   -webkit-border-radius: 4px;
   border-radius: 4px;
@@ -39,14 +39,14 @@
   margin: 10px 0 0 0;
 }
 #dashboard .ui-sortable {
-  border: 2px dashed #CCC;
+  border: 2px dashed #ccc;
   padding: 10px;
 }
 #dashboard .canvas-content {
   padding: 10px;
 }
 #dashboard .canvas-content a.button {
-  color: #5A5A5A;
+  color: #5a5a5a;
   margin: 0 0 0 10px; /* LTR */
   text-decoration: none;
 }
@@ -63,7 +63,7 @@
 }
 #dashboard #disabled-blocks .region {
   background-color: #E0E0D8;
-  border: #CCC 1px solid;
+  border: #ccc 1px solid;
   padding: 10px;
 }
 #dashboard #disabled-blocks h2 {
@@ -73,10 +73,10 @@
 }
 #dashboard #disabled-blocks .block {
   background: #444;
-  color: #FFF;
+  color: #fff;
 }
 #dashboard.customize-inactive #disabled-blocks .block:hover {
-  background: #0074BD;
+  background: #0074bd;
 }
 #dashboard #disabled-blocks .block-placeholder {
   height: 1.6em;
@@ -96,9 +96,9 @@
 }
 #dashboard.customize-inactive #disabled-blocks .block:hover h2 {
   background: #0074BD url(../../misc/draggable.png) no-repeat 0px -39px;
-  color: #FFF;
+  color: #fff;
 }
 #dashboard.customize-inactive .dashboard-region .ui-sortable .block:hover h2 {
   background: #0074BD url(../../misc/draggable.png) no-repeat 3px -36px;
-  color: #FFF;
+  color: #fff;
 }
diff --git a/core/modules/image/image.admin.css b/core/modules/image/image.admin.css
index 3115c8d..efe522f 100644
--- a/core/modules/image/image.admin.css
+++ b/core/modules/image/image.admin.css
@@ -56,5 +56,5 @@ table.image-anchor tr.odd {
   background: none;
 }
 table.image-anchor td {
-  border: 1px solid #CCC;
+  border: 1px solid #ccc;
 }
diff --git a/core/modules/locale/locale.css b/core/modules/locale/locale.css
index 38112b5..66de82b 100644
--- a/core/modules/locale/locale.css
+++ b/core/modules/locale/locale.css
@@ -25,7 +25,7 @@
   padding: 3ex 0 0 1em; /* LTR */
 }
 .language-switcher-locale-session a.active {
-  color: #0062A0;
+  color: #0062a0;
 }
 .language-switcher-locale-session a.session-active {
   color: #000000;
diff --git a/core/modules/simpletest/files/css_test_files/comment_hacks.css b/core/modules/simpletest/files/css_test_files/comment_hacks.css
index c47e842..8b12d6c 100644
--- a/core/modules/simpletest/files/css_test_files/comment_hacks.css
+++ b/core/modules/simpletest/files/css_test_files/comment_hacks.css
@@ -22,7 +22,7 @@ html .clear-block {
 
 /* v1 of the commented backslash hack. This \ character between rules appears to have the effect
 that macIE5 ignores the following rule. Odd, but extremely useful. */
-.bkslshv1 { background-color: #C00; }
+.bkslshv1 { background-color: #c00; }
 .test3 { display:block; }
 
 /**************** A multiline, multistar comment ***************
@@ -34,8 +34,8 @@ that macIE5 ignores the following rule. Odd, but extremely useful. */
   content: "/* ";
 }
 .this_rule_must_stay {
-  color: #F00;
-  background-color: #FFF;
+  color: #f00;
+  background-color: #fff;
 }
 .comment-in-double-quotes:after {
   content: " */";
@@ -45,8 +45,8 @@ that macIE5 ignores the following rule. Odd, but extremely useful. */
   content: '/*';
 }
 .this_rule_must_stay {
-  color: #F00;
-  background-color: #FFF;
+  color: #f00;
+  background-color: #fff;
 }
 .comment-in-single-quotes:after {
   content: '*/';
@@ -56,8 +56,8 @@ that macIE5 ignores the following rule. Odd, but extremely useful. */
   content: '"/*"';
 }
 .this_rule_must_stay {
-  color: #F00;
-  background-color: #FFF;
+  color: #f00;
+  background-color: #fff;
 }
 .comment-in-mixed-quotes:after {
   content: "'*/'";
@@ -67,8 +67,8 @@ that macIE5 ignores the following rule. Odd, but extremely useful. */
   content: '/* \" \' */';
 }
 .this_rule_must_stay {
-  color: #F00;
-  background-color: #FFF;
+  color: #f00;
+  background-color: #fff;
 }
 .comment-in-quotes-with-escaped:after {
   content: "*/ \" \ '";
diff --git a/core/modules/simpletest/files/css_test_files/comment_hacks.css.optimized.css b/core/modules/simpletest/files/css_test_files/comment_hacks.css.optimized.css
index 1feb8f1..4e6615a 100644
--- a/core/modules/simpletest/files/css_test_files/comment_hacks.css.optimized.css
+++ b/core/modules/simpletest/files/css_test_files/comment_hacks.css.optimized.css
@@ -1 +1 @@
-.test1{display:block;}html .clear-block{height:1%;}.clear-block{display:block;font:italic bold 12px/30px Georgia,serif;}.test2{display:block;}.bkslshv1{background-color:#C00;}.test3{display:block;}.test4{display:block;}.comment-in-double-quotes:before{content:"/* ";}.this_rule_must_stay{color:#F00;background-color:#FFF;}.comment-in-double-quotes:after{content:" */";}.comment-in-single-quotes:before{content:'/*';}.this_rule_must_stay{color:#F00;background-color:#FFF;}.comment-in-single-quotes:after{content:'*/';}.comment-in-mixed-quotes:before{content:'"/*"';}.this_rule_must_stay{color:#F00;background-color:#FFF;}.comment-in-mixed-quotes:after{content:"'*/'";}.comment-in-quotes-with-escaped:before{content:'/* \" \' */';}.this_rule_must_stay{color:#F00;background-color:#FFF;}.comment-in-quotes-with-escaped:after{content:"*/ \" \ '";}
+.test1{display:block;}html .clear-block{height:1%;}.clear-block{display:block;font:italic bold 12px/30px Georgia,serif;}.test2{display:block;}.bkslshv1{background-color:#c00;}.test3{display:block;}.test4{display:block;}.comment-in-double-quotes:before{content:"/* ";}.this_rule_must_stay{color:#f00;background-color:#fff;}.comment-in-double-quotes:after{content:" */";}.comment-in-single-quotes:before{content:'/*';}.this_rule_must_stay{color:#f00;background-color:#fff;}.comment-in-single-quotes:after{content:'*/';}.comment-in-mixed-quotes:before{content:'"/*"';}.this_rule_must_stay{color:#f00;background-color:#fff;}.comment-in-mixed-quotes:after{content:"'*/'";}.comment-in-quotes-with-escaped:before{content:'/* \" \' */';}.this_rule_must_stay{color:#f00;background-color:#fff;}.comment-in-quotes-with-escaped:after{content:"*/ \" \ '";}
diff --git a/core/modules/simpletest/files/css_test_files/comment_hacks.css.unoptimized.css b/core/modules/simpletest/files/css_test_files/comment_hacks.css.unoptimized.css
index c47e842..8b12d6c 100644
--- a/core/modules/simpletest/files/css_test_files/comment_hacks.css.unoptimized.css
+++ b/core/modules/simpletest/files/css_test_files/comment_hacks.css.unoptimized.css
@@ -22,7 +22,7 @@ html .clear-block {
 
 /* v1 of the commented backslash hack. This \ character between rules appears to have the effect
 that macIE5 ignores the following rule. Odd, but extremely useful. */
-.bkslshv1 { background-color: #C00; }
+.bkslshv1 { background-color: #c00; }
 .test3 { display:block; }
 
 /**************** A multiline, multistar comment ***************
@@ -34,8 +34,8 @@ that macIE5 ignores the following rule. Odd, but extremely useful. */
   content: "/* ";
 }
 .this_rule_must_stay {
-  color: #F00;
-  background-color: #FFF;
+  color: #f00;
+  background-color: #fff;
 }
 .comment-in-double-quotes:after {
   content: " */";
@@ -45,8 +45,8 @@ that macIE5 ignores the following rule. Odd, but extremely useful. */
   content: '/*';
 }
 .this_rule_must_stay {
-  color: #F00;
-  background-color: #FFF;
+  color: #f00;
+  background-color: #fff;
 }
 .comment-in-single-quotes:after {
   content: '*/';
@@ -56,8 +56,8 @@ that macIE5 ignores the following rule. Odd, but extremely useful. */
   content: '"/*"';
 }
 .this_rule_must_stay {
-  color: #F00;
-  background-color: #FFF;
+  color: #f00;
+  background-color: #fff;
 }
 .comment-in-mixed-quotes:after {
   content: "'*/'";
@@ -67,8 +67,8 @@ that macIE5 ignores the following rule. Odd, but extremely useful. */
   content: '/* \" \' */';
 }
 .this_rule_must_stay {
-  color: #F00;
-  background-color: #FFF;
+  color: #f00;
+  background-color: #fff;
 }
 .comment-in-quotes-with-escaped:after {
   content: "*/ \" \ '";
diff --git a/core/modules/taxonomy/taxonomy.css b/core/modules/taxonomy/taxonomy.css
index 36cd641..433b3d6 100644
--- a/core/modules/taxonomy/taxonomy.css
+++ b/core/modules/taxonomy/taxonomy.css
@@ -1,12 +1,12 @@
 
 tr.taxonomy-term-preview {
-  background-color: #EEE;
+  background-color: #eee;
 }
 tr.taxonomy-term-divider-top {
   border-bottom: none;
 }
 tr.taxonomy-term-divider-bottom {
-  border-top: 1px dotted #CCC;
+  border-top: 1px dotted #ccc;
 }
 .taxonomy-term-description {
   margin: 5px 0 20px;
diff --git a/core/modules/update/update.css b/core/modules/update/update.css
index d30dfb6..80d0bdb 100644
--- a/core/modules/update/update.css
+++ b/core/modules/update/update.css
@@ -100,7 +100,7 @@ table.update,
 }
 
 .update table.version-security .version-title {
-  color: #970F00;
+  color: #970f00;
 }
 
 .update table.version-recommended-strong .version-title {
@@ -109,7 +109,7 @@ table.update,
 
 .update .security-error {
   font-weight: bold;
-  color: #970F00;
+  color: #970f00;
 }
 
 .update .check-manually {
diff --git a/core/modules/user/user.css b/core/modules/user/user.css
index a303307..bbfeb83 100644
--- a/core/modules/user/user.css
+++ b/core/modules/user/user.css
@@ -42,14 +42,14 @@
   font-weight: bold;
 }
 .password-indicator {
-  background-color: #C4C4C4;
+  background-color: #c4c4c4;
   height: 0.3em;
   width: 100%;
 }
 .password-indicator div {
   height: 100%;
   width: 0%;
-  background-color: #47C965;
+  background-color: #47c965;
 }
 input.password-confirm,
 input.password-field {
@@ -66,7 +66,7 @@ div.form-item div.password-suggestions {
   padding: 0.2em 0.5em;
   margin: 0.7em 0;
   width: 38.5em;
-  border: 1px solid #B4B4B4;
+  border: 1px solid #b4b4b4;
 }
 div.password-suggestions ul {
   margin-bottom: 0;
diff --git a/core/themes/bartik/css/style.css b/core/themes/bartik/css/style.css
index a66b95b..63dbf45 100644
--- a/core/themes/bartik/css/style.css
+++ b/core/themes/bartik/css/style.css
@@ -1651,10 +1651,10 @@ div.admin-panel .description {
 
 /* ---------- book ----------- */
 .book-navigation .menu {
-  border-top: 1px solid #D6D6D6;
+  border-top: 1px solid #d6d6d6;
 }
 .book-navigation .book-pager {
-  border-bottom: 1px solid #D6D6D6;
-  border-top: 1px solid #D6D6D6;
+  border-bottom: 1px solid #d6d6d6;
+  border-top: 1px solid #d6D6d6;
   margin: 0;
 }
diff --git a/core/themes/seven/style.css b/core/themes/seven/style.css
index e5869d3..fbc4800 100644
--- a/core/themes/seven/style.css
+++ b/core/themes/seven/style.css
@@ -8,7 +8,7 @@ body {
   font: normal 81.3%/1.538em "Lucida Grande", "Lucida Sans Unicode", sans-serif;
 }
 a {
-  color: #0074BD;
+  color: #0074bd;
   text-decoration: none;
 }
 a:hover {
@@ -937,13 +937,13 @@ div.add-or-remove-shortcuts {
   padding: 1px 8px;
 }
 #field-display-overview tr.field-formatter-settings-changed {
-  background: #FFFFBB;
+  background: #ffb;
 }
 #field-display-overview tr.drag {
-  background: #FFEE77;
+  background: #fe7;
 }
 #field-display-overview tr.field-formatter-settings-editing {
-  background: #D5E9F2;
+  background: #d5e9f2;
 }
 #field-display-overview .field-formatter-settings-edit-form .form-item {
   margin: 10px 0;