Use namespaced data variable to store docs.rs' theme

Author: Nemo157

templates/style/_syntax-themes.scss

@@ -17,10 +17,10 @@ html {
   --color-syntax-string: #718c00;
 }
 
-// To add a new theme, copy the above theme into a new `html[data-theme="name"]`
+// To add a new theme, copy the above theme into a new `html[data-docs-rs-theme="name"]`
 // block below and change the colors
 
-html[data-theme="dark"] {
+html[data-docs-rs-theme="dark"] {
   --color-syntax-foreground: inherit;
   --color-syntax-attribute: #ee6868;
   --color-syntax-background: #2a2a2a;
@@ -39,7 +39,7 @@ html[data-theme="dark"] {
   --color-syntax-string: #83a300;
 }
 
-html[data-theme="ayu"] {
+html[data-docs-rs-theme="ayu"] {
   --color-syntax-foreground: #e6e1cf;
   --color-syntax-attribute: #e6e1cf;
   --color-syntax-background: #191f26;

templates/style/_themes.scss

@@ -32,10 +32,10 @@ html {
   --chart-grid: #ddd;
 }
 
-// To add a new theme, copy the above theme into a new `html[data-theme="name"]`
+// To add a new theme, copy the above theme into a new `html[data-docs-rs-theme="name"]`
 // block below and change the colors
 
-html[data-theme="dark"] {
+html[data-docs-rs-theme="dark"] {
   color-scheme: dark;
   --color-background-code: #2a2a2a;
   --color-background: #353535;
@@ -68,7 +68,7 @@ html[data-theme="dark"] {
   --chart-grid: #4e4e4e;
 }
 
-html[data-theme="ayu"] {
+html[data-docs-rs-theme="ayu"] {
   color-scheme: dark;
   --color-background-code: #191f26;
   --color-background: #0f1419;

templates/theme.js

@@ -1,7 +1,7 @@
 (function() {
     function applyTheme(theme) {
         if (theme) {
-            document.documentElement.dataset.theme = theme;
+            document.documentElement.dataset.docsRsTheme = theme;
         }
     }