MDL-55168 css: fix various errors detected by stylelint

Ignored properties, invalid propertiies, duplicates, invalid selectors..

Detected by stylelint rules:

http://stylelint.io/user-guide/rules/declaration-block-no-ignored-properties
http://stylelint.io/user-guide/rules/selector-type-no-unknown
http://stylelint.io/user-guide/rules/declaration-block-no-duplicate-properties
http://stylelint.io/user-guide/rules/max-line-length
http://stylelint.io/user-guide/rules/no-browser-hacks

blocks/course_overview/styles.css

@@ -32,7 +32,6 @@
 .block_course_overview .welcome_message {
     float: left;
     padding: 10px;
-    vertical-align: middle;
     border-collapse: separate;
     clear: none;
 }

grade/report/singleview/styles.css

@@ -56,7 +56,7 @@
     padding-bottom: 0.5em;
 }
 
-.path-grade-report-singleview itemnav.previtem {
+.path-grade-report-singleview .itemnav.previtem {
     float: left;
 }
 

mod/assign/feedback/editpdf/styles.css

@@ -45,7 +45,6 @@
     user-select: none;
     -moz-user-select: none;
     -webkit-user-select: none;
-    -o-user-select: none;
 }
 
 .assignfeedback_editpdf_widget .pageheader {

mod/data/preset/imagegallery/csstemplate.css

@@ -10,20 +10,16 @@
     border-width: thin;
     border-color: #779;
     background-color: white;
-    display: table-cell;
-    display: inline-table;
     display: inline-block;
 }
 
 .pictureframe {
     padding: 5px;
-    display: table-cell;
-    display: inline-table;
     display: inline-block;
 }
 
 .picturediv {
-    display: inline;
+    display: inline-block;
     max-width: 150px;
     max-height: 200px;
 }

mod/data/styles.css

@@ -118,7 +118,7 @@
     text-align: center;
 }
 
-.mod-data-default-template searchcontrols {
+.mod-data-default-template .searchcontrols {
     text-align: right;
 }
 

mod/scorm/styles.css

@@ -265,8 +265,8 @@
 }
 
 #page-mod-scorm-player #scormpage div.yui3-g-r {
-    *letter-spacing: normal;
-    *word-spacing: -0.43em;
+    letter-spacing: normal;
+    word-spacing: -0.43em;
 }
 
 /**

mod/wiki/styles.css

@@ -284,7 +284,6 @@ a.wiki_newentry:visited {
 
 a.wiki_edit_section {
     font-size: 0.6em;
-    vertical-align: top;
     position: relative;
     float: right;
 }

question/format/xhtml/xhtml.css

@@ -1,5 +1,5 @@
 body {
-    font-family: Verdana, Helvetica, Sans-Serif;
+    font-family: verdana, helvetica, sans-serif;
     background-color: #fff;
     color: #000;
 }