fix(theme-default): fix content headers styles

Author: meteorlxy

packages/@vuepress/theme-default/src/styles/layout.styl

@@ -45,21 +45,6 @@ $mobileSidebarWidth = $sidebarWidth * 0.82;
 }
 
 .theme-container {
-  {$contentClass}:not(.custom) > h1, h2, h3, h4, h5, h6 {
-    margin-top: 0.5rem - $navbarHeight;
-    padding-top: ($navbarHeight + 1rem);
-    margin-bottom: 0;
-
-    &:first-child {
-      margin-top: -1.5rem;
-      margin-bottom: 1rem;
-
-      + p, + pre, + .custom-block {
-        margin-top: 2rem;
-      }
-    }
-  }
-
   &.sidebar-open {
     .sidebar-mask {
       display: block;
@@ -90,6 +75,23 @@ $mobileSidebarWidth = $sidebarWidth * 0.82;
   }
 }
 
+h1, h2, h3, h4, h5, h6 {
+  {$contentClass}:not(.custom) > & {
+    margin-top: 0.5rem - $navbarHeight;
+    padding-top: ($navbarHeight + 1rem);
+    margin-bottom: 0;
+
+    &:first-child {
+      margin-top: -1.5rem;
+      margin-bottom: 1rem;
+
+      + p, + pre, + .custom-block {
+        margin-top: 2rem;
+      }
+    }
+  }
+}
+
 {$contentClass}:not(.custom) {
   @extend $wrapper;