styles: Add custom max width content

Author: ktquez

styles/index.styl

@@ -18,6 +18,7 @@
  --text-color-code: $textColorCode
  --border-color: $borderColor
  --outline-color: $outlineColor
+ --content-max-width: $contentMaxWidth
 
 html.dark-mode
  --bg: $darkBg

styles/override-components.styl

@@ -18,6 +18,9 @@
  color: var(--color)
  border-top-color var(--border-color)
 
+.theme-default-content:not(.custom), .page-edit, .page-nav 
+ max-width: var(--content-max-width)
+
 .navbar .site-name
  color: var(--color)
 

styles/palette.styl

@@ -1,3 +1,5 @@
+$contentMaxWidth ?= 768px
+
 $accentColor ?= #3ab982
 $darkAccentColor ?= #3ab982
 $sepiaAccentColor ?= #3ab982