diff --git a/css/style.css b/css/style.css
index 4cd977f..cb94eea 100644
--- a/css/style.css
+++ b/css/style.css
@@ -1,89 +1,214 @@
+/* variables */
 :root {
 	--font-size: 12pt;
 	--line-height: 1.625;
-	--height-unit: calc(var(--font-size) * var(--line-height));
-	--width-unit: 1ch;
-	--padding-left: calc(1 * var(--width-unit));
-	--padding-right: calc(1 * var(--width-unit));
-	--padding-top: calc(1 * var(--height-unit));
-	--padding-bottom: calc(1 * var(--height-unit));
-	--gap-vertical: calc(1 * var(--height-unit));
-	--gap-horizontal: calc(2 * var(--width-unit));
-	--column-width: clamp(32ch, 72ch, calc(100vw - var(--gap-horizontal) - var(--padding-left) - var(--padding-right) - var(--width-unit)));
-	font: var(--font-size)/var(--line-height) monospace;
-	color-scheme: light dark;
+  --font-family: monospace;
+
+  /* font-derived vertical and horizontal units */
+  --v-un: calc(var(--font-size) * var(--line-height));
+  --h-un: 1ch;
+
+  /* gaps and paddings */
+  --body-padding-h: var(--h-un);
+  --body-padding-v: var(--v-un);
+  --main-gap-h: calc(2 * var(--h-un));
+  --main-gap-v: 0;
+
+  /* font-derived column width */
+  --max-col-w: calc(100vw - (2 * var(--body-padding-h)) - var(--main-gap-h) - 1ch);
+  --col-w: clamp(32ch, 72ch, var(--max-col-w));
+
+  /* colors */
+  --fg-c: #000000;
+  --bg-c: #ffffff;
+	--link-c: hsl(240 100% 50%);
+	--visited-c: hsl(270 100% 50%);
+	--active-c: hsl(0 100% 50%);
+}
+
+@media (prefers-color-scheme: dark) {
+  :root {
+    --fg-c: #ffffff;
+    --bg-c: #000000;
+    --link-c: hsl(240 100% 75%);
+    --visited-c: hsl(270 100% 75%);
+    --active-c: hsl(0 100% 75%);
+  }
 }
 
 /* reset */
 * {
 	box-sizing: border-box;
+  margin: unset;
+  hyphens: auto;
 }
-body {
-	color: light-dark(#000000, #ffffff);
-	background-color: light-dark(#ffffff, #000000);
-	margin: 0;
+
+/* root */
+:root {
+	color: var(--fg-c);
+	background-color: var(--bg-c);
+  font: var(--font-size)/var(--line-height) var(--font-family);
 }
+
+/* content sectioning */
+address {
+  font-style: unset;
+}
+
 h1, h2, h3, h4, h5, h6 {
-	font: inherit;
+	font-size: unset;
+  font-weight: bold;
 }
-h1 {
-	font-weight: bold;
-    margin: var(--height-unit) var(--height-unit) 0 0;
+
+article {
+  counter-reset: heading;
 }
-h2, h3, h4, h5, h6 {
-	font-style: italic;
-    margin: var(--height-unit) var(--height-unit) 0 0;
+
+article h1:before {
+	content:
+    counter(heading)". ";
+	counter-increment: heading;
 }
-p {
-    margin: var(--height-unit) 0 0 0;
-	hyphens: auto;
+
+article h1 {
+	counter-reset: subheading;
 }
+
+article h2:before {
+	content:
+    counter(heading)"."
+    counter(subheading)". ";
+	counter-increment: subheading;
+}
+
+article h2 {
+  counter-reset: subsubheading;
+}
+
+article h3:before {
+  content:
+    counter(heading)"."
+    counter(subheading)"."
+    counter(subsubheading)". ";
+  counter-increment: subsubheading;
+}
+
+article h3 {
+  counter-reset: subsubsubheading;
+}
+
+article h4:before {
+  content:
+    counter(heading)"."
+    counter(subheading)"."
+    counter(subsubheading)"."
+    counter(subsubsubheading)". ";
+  counter-increment: subsubsubheading;
+}
+
+article h4 {
+  counter-reset: subsubsubsubheading;
+}
+
+article h5:before {
+  content:
+    counter(heading)"."
+    counter(subheading)"."
+    counter(subsubheading)"."
+    counter(subsubsubheading)"."
+    counter(subsubsubsubheading)". ";
+  counter-increment: subsubsubsubheading;
+}
+
+article h5 {
+  counter-reset: subsubsubsubsubheading;
+}
+
+article h6:before {
+  content:
+    counter(heading)"."
+    counter(subheading)"."
+    counter(subsubheading)"."
+    counter(subsubsubheading)"."
+    counter(subsubsubsubheading)"."
+    counter(subsubsubsubsubheading)". ";
+  counter-increment: subsubsubsubsubheading;
+}
+
+/* text content */
+:is(blockquote, dl, figure, hr, menu, ol, p, pre, ul) +
+:is(blockquote, dl, figure, hr, menu, ol, p, pre, ul) {
+  margin-block-start: var(--v-un);
+}
+
 blockquote {
-	margin: var(--height-unit) calc(2 * var(--width-unit));
+	margin-inline: calc(4 * var(--h-un));
 }
-ul, ol {
-	margin: var(--height-unit) 0;
-	padding: 0 0 0 calc(4 * var(--width-unit));
+
+ol, ul, menu {
+  padding-inline-start: calc(4 * var(--h-un));
 }
+
+:is(ol, ul, menu) :is(ol, ul, menu) {
+  margin-block: unset;
+}
+
 ul>li::marker {
 	content: "- ";
 }
+
 hr {
-	color: inherit;
-	border: none;
-	margin: var(--height-unit) 0;
-}
-hr:after {
-	content: "---";
+	color: unset;
+	border: unset;
+  border-top: var(--fg-c) dotted 0.1pt;
 }
 
-/* main layout */
+/* inline text semantics */
+a {
+  cursor: pointer;
+  text-decoration: underline;
+}
+
+a:link {
+  color: var(--link-c);
+}
+
+a:link:active {
+  color: var(--active-c);
+}
+
+a:visited {
+  color: var(--visited-c);
+}
+
+a:visited:active {
+  color: var(--active-c);
+}
+
+/* layout */
 body {
-	padding: var(--height-unit) var(--width-unit);
 	width: 100vw;
 	height: 100vh;
+	padding: var(--body-padding-v) var(--body-padding-h);
 }
 
-/* secondary grid */
 body>main {
 	height: 100%;
 	display: grid;
 	grid-auto-flow: column;
-	grid-template-columns: repeat(auto-fit, var(--column-width));
-	grid-gap: var(--gap-horizontal);
+  grid-auto-columns: var(--col-w);
+  gap: var(--main-gap-v) var(--main-gap-h);
 	overflow-x: scroll;
-	scroll-snap-type: x proximity;
 }
+
 body>main>article {
-	scroll-snap-align: start;
-	scroll-snap-stop: always;
-	width: var(--column-width);
 	overflow-y: scroll;
 }
-body>main>article>header>h1 {
-	margin: unset;
-	display: inline-block;
+
+body>main>article>header {
+  margin-block-end: var(--v-un);
 }
-body>main>article>article {
-	margin: var(--height-unit) 0 0 0;
+
+body>main>article>footer {
+  margin-block-start: var(--v-un);
 }