doc: improve header styling for API docs

Sizes were mostly decided by using http://type-scale.com/ with the 1.250 "Major Third" scaling. PR-URL: #8811 Reviewed-By: Roman Reiss <[email protected]> Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Prince John Wesley <[email protected]> Reviewed-By: Rod Vagg <[email protected]> Reviewed-By: Phillip Johnsen <[email protected]>

Author: Fishrock123

doc/api_assets/style.css

@@ -15,6 +15,31 @@ body{
 background:#fff;
 }
 
+h1,h2,h3,h4{
+margin:.8em0.5em;
+line-height:1.2;
+}
+
+h5,h6{
+margin:1em0.8em;
+line-height:1.2;
+}
+
+h1{
+margin-top:0;
+font-size:2.441em;
+}
+
+h2{font-size:1.953em}
+
+h3{font-size:1.563em}
+
+h4{font-size:1.25em}
+
+h5{font-size:1em}
+
+h6{font-size:.8em}
+
 pre,tt,code, .pre,span.type,a.type{
 font-family: Monaco, Consolas,"Lucida Console", monospace;
 }
@@ -127,7 +152,7 @@ abbr{
 p{
 position: relative;
 text-rendering: optimizeLegibility;
-margin:001em0;
+margin:001.125em0;
 line-height:1.5em;
 }
 
@@ -180,10 +205,10 @@ h1, h2, h3, h4, h5, h6{
 text-rendering: optimizeLegibility;
 font-weight:700;
 position: relative;
-margin-bottom:.5em;
 }
 
 headerh1{
+font-size:2em;
 line-height:2em;
 margin:0;
 }
@@ -198,30 +223,15 @@ header h1{
 background-color:#ccc;
 }
 
-#toc+h1{
-margin-top:1em;
-padding-top:0;
-}
-
-h2{
-font-size:1.5em;
-margin:1em0.5em;
-}
-
 h2+h2{
 margin:00.5em;
 }
 
-h3{
-font-size:1em;
-margin:1.5em0.5em;
-}
-
 h3+h3{
 margin:00.5em;
 }
 
-h2,h3,h4{
+h2,h3,h4,h5{
 position: relative;
 padding-right:40px;
 }
@@ -244,16 +254,6 @@ h1 span a, h2 span a, h3 span a, h4 span a{
 font-weight: bold;
 }
 
-h5{
-font-size:1.125em;
-line-height:1.4em;
-}
-
-h6{
-font-size:1em;
-line-height:1.4667em;
-}
-
 pre,tt,code{
 line-height:1.5em;
 margin:0; padding:0;
@@ -353,7 +353,7 @@ hr{
 margin-bottom:0;
 }
 
-ptt,pcode,licode{
+tt,code{
 font-size:.9em;
 color:#040404;
 background-color:#f2f2f2;