css: adjust sidebar line height to improve readability (#1045)

* css: adjust the line height to improve readability

When a heading is long, it will be word-wrapped. The current value of
line-height is very high, causing lines that are word-wrapped to appear
as new items.

The fix is to reduce the line-height, and instead use padding as a way to
distance items apart.

Author: sorawee

CHANGES.md

@@ -29,6 +29,9 @@ Tags:
 ### Changed
 - Style: Remove font fallback to Helvetica, Arial (@Julow, #1028)
 
+### Changed
+- Style: Adjusted line height in the TOC to improve readability (@sorawee, #1045)
+
 # 2.3.0
 
 ### Added

src/html_support_files/odoc.css

@@ -779,7 +779,7 @@ td.def-doc *:first-child {
   font-size: 0.95em;
   color: var(--color);
   font-weight: 400;
-  line-height: 1.6em;
+  line-height: 1.2em;
   display: block;
 }
 
@@ -1070,14 +1070,15 @@ td.def-doc *:first-child {
 
 .odoc-toc li ul {
   margin: 0px;
+  padding-top: 0.25em;
 }
 
 .odoc-toc ul {
   list-style-type: none;
 }
 
 .odoc-toc ul li {
-  margin: 0;
+  padding: 0.25em 0;
 }
 
 .odoc-toc>ul>li {