diff --git a/css/index.css b/css/index.css
index 50fe012..e3e8163 100644
--- a/css/index.css
+++ b/css/index.css
@@ -1,175 +1,188 @@
 :root {
-	--red: #C5004A;
-	--darkred: #7F0036;
-	--lightgray: #e0e0e0;
-	--gray: #C0C0C0;
-	--darkgray: #666;
-	--navy: #17050F;
-	--blue: #082840;
-	--white: #fff;
+  --red: #C5004A;
+  --darkred: #7F0036;
+  --lightgray: #e0e0e0;
+  --gray: #C0C0C0;
+  --darkgray: #333;
+  --navy: #17050F;
+  --blue: #082840;
+  --white: #fff;
 }
 * {
-	box-sizing: border-box;
+  box-sizing: border-box;
 }
 html,
 body {
-	padding: 0;
-	margin: 0;
-	font-family: sans-serif;
+  padding: 0;
+  margin: 0;
+  font-family: sans-serif;
   color: var(--darkgray);
   background-color: var(--white);
 }
 p:last-child {
-	margin-bottom: 0;
+  margin-bottom: 0;
 }
 p,
 .tmpl-post li,
 img {
-	max-width: 37.5em; /* 600px /16 */
+  max-width: 37.5em; /* 600px /16 */
 }
 p,
 .tmpl-post li {
-	line-height: 1.45;
+  line-height: 1.45;
 }
 a[href] {
-	color: var(--blue);
+  color: var(--blue);
 }
 a[href]:visited {
-	color: var(--navy);
+  color: var(--navy);
 }
 main {
-	padding: 1rem;
+  padding: 1rem;
 }
 main :first-child {
-	margin-top: 0;
+  margin-top: 0;
 }
 header {
-	border-bottom: 1px dashed var(--lightgray);
+  border-bottom: 1px dashed var(--lightgray);
 }
 header:after {
-	content: "";
-	display: table;
-	clear: both;
+  content: "";
+  display: table;
+  clear: both;
 }
 pre,
 code {
-	font-family: Consolas, Menlo, Monaco, "Andale Mono WT", "Andale Mono", "Lucida Console", "Lucida Sans Typewriter", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Liberation Mono", "Nimbus Mono L", "Courier New", Courier, monospace;
-	line-height: 1.5;
+  font-family: Consolas, Menlo, Monaco, "Andale Mono WT", "Andale Mono", "Lucida Console", "Lucida Sans Typewriter", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Liberation Mono", "Nimbus Mono L", "Courier New", Courier, monospace;
+  line-height: 1.5;
 }
 pre {
-	font-size: 14px;
-	line-height: 1.375;
-	direction: ltr;
-	text-align: left;
-	white-space: pre;
-	word-spacing: normal;
-	word-break: normal;
-	-moz-tab-size: 2;
-	-o-tab-size: 2;
-	tab-size: 2;
-	-webkit-hyphens: none;
-	-moz-hyphens: none;
-	-ms-hyphens: none;
-	hyphens: none;
-	padding: 1em;
-	margin: .5em 0;
-	background-color: #f6f6f6;
+  font-size: 14px;
+  line-height: 1.375;
+  direction: ltr;
+  text-align: left;
+  white-space: pre;
+  word-spacing: normal;
+  word-break: normal;
+  -moz-tab-size: 2;
+  -o-tab-size: 2;
+  tab-size: 2;
+  -webkit-hyphens: none;
+  -moz-hyphens: none;
+  -ms-hyphens: none;
+  hyphens: none;
+  padding: 1em;
+  margin: .5em 0;
+  background-color: #f6f6f6;
 }
 .highlight-line {
-	padding: 0.125em 1em; /* 2px 16px /16 */
+  display: block;
+  padding: 0.125em 1em;
+  text-decoration: none; /* override del, ins, mark defaults */
+  color: inherit; /* override del, ins, mark defaults */
 }
+
+/* allow highlighting empty lines */
+.highlight-line:empty:before {
+  content: " ";
+}
+/* avoid double line breaks when using display: block; */
+.highlight-line + br {
+  display: none;
+}
+
 .highlight-line-isdir {
-	color: #b0b0b0;
-	background-color: #222;
+  color: #b0b0b0;
+  background-color: #222;
 }
 .highlight-line-active {
-	background-color: #444;
-	background-color: hsla(0, 0%, 27%, .8);
+  background-color: #444;
+  background-color: hsla(0, 0%, 27%, .8);
 }
 .highlight-line-add {
-	background-color: #45844b;
+  background-color: #45844b;
 }
 .highlight-line-remove {
-	background-color: #902f2f;
+  background-color: #902f2f;
 }
 
 /* Header */
 .home {
-	padding: 0 1rem;
-	float: left;
-	margin: 1rem 0; /* 16px /16 */
-	font-size: 1em; /* 16px /16 */
+  padding: 0 1rem;
+  float: left;
+  margin: 1rem 0; /* 16px /16 */
+  font-size: 1em; /* 16px /16 */
 }
 .home :link:not(:hover) {
-	text-decoration: none;
+  text-decoration: none;
 }
 
 /* Nav */
 .nav {
-	padding: 0;
-	list-style: none;
-	float: left;
-	margin-left: 1em;
+  padding: 0;
+  list-style: none;
+  float: left;
+  margin-left: 1em;
 }
 .nav-item {
-	display: inline-block;
-	margin-right: 1em;
+  display: inline-block;
+  margin-right: 1em;
 }
 .nav-item a[href]:not(:hover) {
-	text-decoration: none;
+  text-decoration: none;
 }
 .nav-item-active {
-	font-weight: 700;
-	text-decoration: underline;
+  font-weight: 700;
+  text-decoration: underline;
 }
 
 /* Posts list */
 .postlist {
-	list-style: none;
-	padding: 0;
+  list-style: none;
+  padding: 0;
 }
 .postlist-item {
-	counter-increment: start-from -1;
+  counter-increment: start-from -1;
 }
 .postlist-item:before {
-	display: inline-block;
-	pointer-events: none;
-	content: "" counter(start-from, decimal-leading-zero) ". ";
-	line-height: 100%;
-	text-align: right;
+  display: inline-block;
+  pointer-events: none;
+  content: "" counter(start-from, decimal-leading-zero) ". ";
+  line-height: 100%;
+  text-align: right;
 }
 .postlist-date,
 .postlist-item:before {
-	font-size: 0.8125em; /* 13px /16 */
-	color: var(--darkgray);
+  font-size: 0.8125em; /* 13px /16 */
+  color: var(--darkgray);
 }
 .postlist-date {
-	word-spacing: -0.5px;
+  word-spacing: -0.5px;
 }
 .postlist-link {
-	display: inline-block;
-	padding: 0.25em 0.1875em; /* 4px 3px /16 */
+  display: inline-block;
+  padding: 0.25em 0.1875em; /* 4px 3px /16 */
 }
 .postlist-item-active .postlist-link {
-	font-weight: bold;
+  font-weight: bold;
 }
 .tmpl-home .postlist-link {
-	font-size: 1.1875em; /* 19px /16 */
-	font-weight: 700;
+  font-size: 1.1875em; /* 19px /16 */
+  font-weight: 700;
 }
 
 
 /* Tags */
 .tag {
-	display: inline-block;
-	vertical-align: text-top;
-	text-transform: uppercase;
-	font-size: 0.625em; /* 10px /16 */
-	padding: 2px 4px;
-	margin-left: 0.8em; /* 8px /10 */
-	background-color: var(--red);
-	color: var(--white);
-	border-radius: 0.25em; /* 3px /12 */
+  display: inline-block;
+  vertical-align: text-top;
+  text-transform: uppercase;
+  font-size: 0.625em; /* 10px /16 */
+  padding: 2px 4px;
+  margin-left: 0.8em; /* 8px /10 */
+  background-color: var(--red);
+  color: var(--white);
+  border-radius: 0.25em; /* 3px /12 */
   text-decoration: none;
 }
 a[href].tag,
@@ -179,27 +192,27 @@ a[href].tag:visited {
 
 /* Warning */
 .warning {
-	background-color: #ffc;
-	padding: 1em 0.625em; /* 16px 10px /16 */
+  background-color: #ffc;
+  padding: 1em 0.625em; /* 16px 10px /16 */
 }
 .warning ol:only-child {
-	margin: 0;
+  margin: 0;
 }
 
 /* Direct Links / Markdown Headers */
 .direct-link {
-	font-family: sans-serif;
-	text-decoration: none;
-	font-style: normal;
-	margin-left: .1em;
+  font-family: sans-serif;
+  text-decoration: none;
+  font-style: normal;
+  margin-left: .1em;
 }
 a[href].direct-link,
 a[href].direct-link:visited {
-	color: transparent;
+  color: transparent;
 }
 a[href].direct-link:focus,
 a[href].direct-link:focus:visited,
 :hover > a[href].direct-link,
 :hover > a[href].direct-link:visited {
-	color: #aaa;
+  color: #aaa;
 }