fix: Prevent scrolling behind menus and modals in Safari iOS (#35183)

app/javascript/mastodon/features/ui/components/body_scroll_lock.tsx

@@ -1,71 +1,30 @@
-import { useLayoutEffect, useEffect, useState } from 'react';
+import { useLayoutEffect } from 'react';
 
 import { createAppSelector, useAppSelector } from 'mastodon/store';
-import { getScrollbarWidth } from 'mastodon/utils/scrollbar';
 
 const getShouldLockBodyScroll = createAppSelector(
   [
     (state) => state.navigation.open,
     (state) => state.modal.get('stack').size > 0,
   ],
-  (isMobileMenuOpen: boolean, isModalOpen: boolean) => {
-    return isMobileMenuOpen || isModalOpen;
-  },
+  (isMobileMenuOpen: boolean, isModalOpen: boolean) =>
+    isMobileMenuOpen || isModalOpen,
 );
 
 /**
- * This component locks scrolling on the `body` element when
+ * This component locks scrolling on the body when
  * `getShouldLockBodyScroll` returns true.
- *
- * The scrollbar width is taken into account and written to
- * a CSS custom property `--root-scrollbar-width`
  */
 
 export const BodyScrollLock: React.FC = () => {
   const shouldLockBodyScroll = useAppSelector(getShouldLockBodyScroll);
 
   useLayoutEffect(() => {
-    document.body.classList.toggle('with-modals--active', shouldLockBodyScroll);
+    document.documentElement.classList.toggle(
+      'has-modal',
+      shouldLockBodyScroll,
+    );
   }, [shouldLockBodyScroll]);
 
-  const [scrollbarWidth, setScrollbarWidth] = useState(() =>
-    getScrollbarWidth(),
-  );
-
-  useEffect(() => {
-    const handleResize = () => {
-      setScrollbarWidth(getScrollbarWidth());
-    };
-    window.addEventListener('resize', handleResize, { passive: true });
-    return () => {
-      window.removeEventListener('resize', handleResize);
-    };
-  }, []);
-
-  // Inject style element to make scrollbar width available
-  // as CSS custom property
-  useLayoutEffect(() => {
-    const nonce = document
-      .querySelector('meta[name=style-nonce]')
-      ?.getAttribute('content');
-
-    if (nonce) {
-      const styleEl = document.createElement('style');
-      styleEl.nonce = nonce;
-      styleEl.innerHTML = `
-        :root {
-          --root-scrollbar-width: ${scrollbarWidth}px;
-        }
-      `;
-      document.head.appendChild(styleEl);
-
-      return () => {
-        document.head.removeChild(styleEl);
-      };
-    }
-
-    return () => '';
-  }, [scrollbarWidth]);
-
   return null;
 };

app/javascript/mastodon/utils/scrollbar.ts

@@ -1,19 +0,0 @@
-import { isMobile } from '../is_mobile';
-
-export const getScrollbarWidth = () => {
-  if (isMobile(window.innerWidth)) {
-    return 0;
-  }
-  const outer = document.createElement('div');
-  outer.style.visibility = 'hidden';
-  outer.style.overflow = 'scroll';
-  document.body.appendChild(outer);
-
-  const inner = document.createElement('div');
-  outer.appendChild(inner);
-
-  const scrollbarWidth = outer.offsetWidth - inner.offsetWidth;
-  outer.remove();
-
-  return scrollbarWidth;
-};

app/javascript/styles/mastodon/basics.scss

@@ -1,6 +1,20 @@
 @use 'variables' as *;
 @use 'functions' as *;
 
+html.has-modal {
+  &,
+  body {
+    touch-action: none;
+    overscroll-behavior: none;
+    -webkit-overflow-scrolling: auto;
+    scrollbar-gutter: stable;
+  }
+
+  body {
+    overflow: hidden !important;
+  }
+}
+
 body {
   font-family: $font-sans-serif, sans-serif;
   background: var(--background-color);
@@ -64,21 +78,6 @@ body {
       height: 100%;
       padding-bottom: env(safe-area-inset-bottom);
     }
-
-    &.with-modals--active {
-      overflow-y: hidden;
-      overscroll-behavior: none;
-      margin-right: var(--root-scrollbar-width, 0);
-    }
-  }
-
-  &.with-modals {
-    overflow-x: hidden;
-    overflow-y: scroll;
-
-    &--active {
-      overflow-y: hidden;
-    }
   }
 
   &.player {

app/javascript/styles/mastodon/components.scss

@@ -2896,10 +2896,6 @@ a.account__display-name {
   border-top: 1px solid var(--background-border-color);
   box-sizing: border-box;
 
-  .with-modals--active & {
-    padding-right: var(--root-scrollbar-width);
-  }
-
   .layout-multiple-columns & {
     display: none;
   }
@@ -3170,7 +3166,7 @@ a.account__display-name {
     .navigation-panel {
       margin: 0;
       border-inline-start: 1px solid var(--background-border-color);
-      height: 100vh;
+      height: 100dvh;
     }
 
     .navigation-panel__banner,
@@ -3228,6 +3224,7 @@ a.account__display-name {
     .navigation-panel {
       width: 284px;
       overflow-y: auto;
+      scrollbar-width: thin;
 
       &__menu {
         flex-shrink: 0;