diff --git a/src/build/template.html b/src/build/template.html
index 94f89588..6f534779 100644
--- a/src/build/template.html
+++ b/src/build/template.html
@@ -34,13 +34,19 @@
 
   <style id="theBottomNavStyle" media="only x">
     :root {
-      --nav-top: calc(100vh - var(--nav-total-height));
-      --nav-bottom: 0px;
+      --nav-top: calc(100dvh - var(--nav-total-height));
+      --nav-bottom: initial;
       --main-content-pad-top: 0px;
       --main-content-pad-bottom: var(--main-content-pad-vertical);
       --toast-gap-bottom: var(--nav-total-height);
       --fab-gap-top: 0px;
     }
+    @supports not (height: 1dvh) {
+      /* In browsers that don't support dvh, use the large-small-dynamic-viewport-units-polyfill */
+      :root {
+        --nav-top: calc((100 * var(--1dvh)) - var(--nav-total-height));
+      }
+    }
   </style>
 
   <style id="theGrayscaleStyle" media="only x">
diff --git a/src/routes/_thirdparty/large-small-dynamic-viewport-units-polyfill/LICENSE b/src/routes/_thirdparty/large-small-dynamic-viewport-units-polyfill/LICENSE
new file mode 100644
index 00000000..6cd7b792
--- /dev/null
+++ b/src/routes/_thirdparty/large-small-dynamic-viewport-units-polyfill/LICENSE
@@ -0,0 +1,7 @@
+Copyright <YEAR> <COPYRIGHT HOLDER>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/src/routes/_thirdparty/large-small-dynamic-viewport-units-polyfill/dynamic-viewport-utils-polyfill.js b/src/routes/_thirdparty/large-small-dynamic-viewport-units-polyfill/dynamic-viewport-utils-polyfill.js
new file mode 100644
index 00000000..2d3fb45b
--- /dev/null
+++ b/src/routes/_thirdparty/large-small-dynamic-viewport-units-polyfill/dynamic-viewport-utils-polyfill.js
@@ -0,0 +1,24 @@
+// via https://github.com/joppuyo/large-small-dynamic-viewport-units-polyfill/blob/93782ffff5d76f46b71591b859aac44f3cd591b2/src/index.js
+// with some stuff removed that we don't need
+import { throttleTimer } from '../../_utils/throttleTimer.js'
+
+// Don't execute this resize listener more than the browser can paint
+const rafAlignedResize = process.browser && throttleTimer(requestAnimationFrame)
+
+function setVh () {
+  const dvh = window.innerHeight * 0.01
+  document.documentElement.style.setProperty('--1dvh', (dvh + 'px'))
+}
+
+if (process.browser) {
+  // We run the calculation as soon as possible (eg. the script is in document head)
+  setVh()
+
+  // We run the calculation again when DOM has loaded
+  document.addEventListener('DOMContentLoaded', setVh)
+
+  // We run the calculation when window is resized
+  window.addEventListener('resize', () => {
+    rafAlignedResize(setVh)
+  })
+}
diff --git a/src/routes/_utils/polyfills/asyncPolyfills.js b/src/routes/_utils/polyfills/asyncPolyfills.js
index 4002d92b..deebe785 100644
--- a/src/routes/_utils/polyfills/asyncPolyfills.js
+++ b/src/routes/_utils/polyfills/asyncPolyfills.js
@@ -37,3 +37,7 @@ export const importIntlListFormat = async () => { // has to be imported serially
     /* webpackChunkName: '$polyfill$-internationalization' */ '@formatjs/intl-listformat/locale-data/en.js'
   )
 }
+
+export const importDynamicViewportUnitsPolyfill = () => import(
+  /* webpackChunkName: '$polyfill$-dynamic-viewport-units' */ '../../_thirdparty/large-small-dynamic-viewport-units-polyfill/dynamic-viewport-utils-polyfill.js'
+)
diff --git a/src/routes/_utils/polyfills/loadPolyfills.js b/src/routes/_utils/polyfills/loadPolyfills.js
index 1f1d36b7..a0061610 100644
--- a/src/routes/_utils/polyfills/loadPolyfills.js
+++ b/src/routes/_utils/polyfills/loadPolyfills.js
@@ -1,4 +1,5 @@
 import {
+  importDynamicViewportUnitsPolyfill,
   importIntlListFormat,
   importIntlLocale, importIntlPluralRules, importIntlRelativeTimeFormat,
   importRequestIdleCallback
@@ -25,7 +26,8 @@ export async function loadPolyfills () {
   mark('loadPolyfills')
   await Promise.all([
     typeof requestIdleCallback !== 'function' && importRequestIdleCallback(),
-    loadIntlPolyfillsIfNecessary()
+    loadIntlPolyfillsIfNecessary(),
+    !CSS.supports('height: 1dvh') && importDynamicViewportUnitsPolyfill()
   ])
   stop('loadPolyfills')
 }