diff --git a/ios/Sources/WebViewController.swift b/ios/Sources/WebViewController.swift
index b046423..2e06a64 100644
--- a/ios/Sources/WebViewController.swift
+++ b/ios/Sources/WebViewController.swift
@@ -100,10 +100,12 @@ final class WebViewController: UIViewController, WKNavigationDelegate {
         /// CSS zoom is part of layout, so the page measures itself correctly; body's own width
         /// and height are divided back out because its containing block is not zoomed.
         static func script(_ zoom: Double) -> String {
-            let css = zoom == 1
-                ? ""
-                : "body{zoom:\(zoom);width:calc(100%/\(zoom))!important;"
-                  + "height:calc(100dvh/\(zoom))!important}"
+            // No width. A percentage resolves against the containing block in the zoomed
+            // element's own units, so 100% is already the full width -- dividing it again left
+            // the page filling four fifths of the window and then three fifths as the zoom went
+            // up. A block fills its container by itself. dvh is the exception: viewport units do
+            // not know about zoom, so the height does have to be divided back out.
+            let css = zoom == 1 ? "" : "body{zoom:\(zoom);height:calc(100dvh/\(zoom))!important}"
             return "(function(){var id='ipx-zoom';var s=document.getElementById(id);"
                 + "if(!s){s=document.createElement('style');s.id=id;"
                 + "(document.head||document.documentElement).appendChild(s)}"