diff --git a/packages/overlayscrollbars/src/index.ts b/packages/overlayscrollbars/src/index.ts
index 0f35efe..aa80cd1 100644
--- a/packages/overlayscrollbars/src/index.ts
+++ b/packages/overlayscrollbars/src/index.ts
@@ -1,6 +1,7 @@
 import { createDOM } from 'support/dom';
 import { getEnvironment } from 'environment';
 import { createSizeObserver } from 'overlayscrollbars/observers/SizeObserver';
+import { createTrinsicObserver } from 'overlayscrollbars/observers/TrinsicObserver';
 
 const abc = {
   a: 1,
@@ -12,6 +13,7 @@ export default () => {
   return [
     getEnvironment(),
     createSizeObserver(document.body, () => {}),
+    createTrinsicObserver(document.body, () => {}),
     createDOM(
       '\
     <div class="os-host">\
diff --git a/packages/overlayscrollbars/src/overlayscrollbars.scss b/packages/overlayscrollbars/src/overlayscrollbars.scss
index eae946d..e31bb56 100644
--- a/packages/overlayscrollbars/src/overlayscrollbars.scss
+++ b/packages/overlayscrollbars/src/overlayscrollbars.scss
@@ -1,4 +1,5 @@
 @import './sizeobserver.scss';
+@import './trinsicobserver.scss';
 
 #os-environment {
   position: fixed;
diff --git a/packages/overlayscrollbars/src/overlayscrollbars/observers/SizeObserver.ts b/packages/overlayscrollbars/src/overlayscrollbars/observers/SizeObserver.ts
index 297d45f..914d8fa 100644
--- a/packages/overlayscrollbars/src/overlayscrollbars/observers/SizeObserver.ts
+++ b/packages/overlayscrollbars/src/overlayscrollbars/observers/SizeObserver.ts
@@ -52,7 +52,7 @@ export const createSizeObserver = (
     onSizeChangedCallback(dir === true);
   };
   const offListeners: (() => void)[] = [];
-  let appearCallback: (...args: any) => any = onSizeChangedCallbackProxy;
+  let appearCallback: ((...args: any) => any) | null = appear ? onSizeChangedCallbackProxy : null;
 
   if (ResizeObserverConstructor) {
     const resizeObserverInstance = new ResizeObserverConstructor(onSizeChangedCallbackProxy);
@@ -81,7 +81,9 @@ export const createSizeObserver = (
     };
     const onResized = function () {
       rAFId = 0;
-      if (!isDirty) return;
+      if (!isDirty) {
+        return;
+      }
 
       cacheSize = currSize;
       onSizeChangedCallbackProxy();
@@ -114,7 +116,7 @@ export const createSizeObserver = (
       height: scrollAmount,
     });
     reset();
-    appearCallback = onScroll;
+    appearCallback = appear ? onScroll : reset;
   }
 
   if (direction) {
@@ -140,7 +142,8 @@ export const createSizeObserver = (
     );
   }
 
-  if (appear) {
+  // appearCallback is always needed on scroll-observer strategy to reset it
+  if (appearCallback) {
     addClass(sizeObserver, classNameSizeObserverAppear);
     offListeners.push(on(sizeObserver, animationStartEventName, appearCallback));
   }
diff --git a/packages/overlayscrollbars/src/overlayscrollbars/observers/TrinsicObserver.ts b/packages/overlayscrollbars/src/overlayscrollbars/observers/TrinsicObserver.ts
index 1adf14b..88b09f9 100644
--- a/packages/overlayscrollbars/src/overlayscrollbars/observers/TrinsicObserver.ts
+++ b/packages/overlayscrollbars/src/overlayscrollbars/observers/TrinsicObserver.ts
@@ -36,6 +36,7 @@ export const createTrinsicObserver = (
       createSizeObserver(trinsicObserver, () => {
         const newSize = offsetSize(trinsicObserver);
         const newHeightIntrinsic = newSize.h === 0;
+
         if (newHeightIntrinsic !== heightIntrinsic) {
           onTrinsicChangedCallback(false, newSize.h === 0);
           heightIntrinsic = newHeightIntrinsic;
diff --git a/packages/overlayscrollbars/tests/puppeteer/SizeObserver/index.browser.ts b/packages/overlayscrollbars/tests/puppeteer/SizeObserver/index.browser.ts
index 7ac4b42..8237b89 100644
--- a/packages/overlayscrollbars/tests/puppeteer/SizeObserver/index.browser.ts
+++ b/packages/overlayscrollbars/tests/puppeteer/SizeObserver/index.browser.ts
@@ -75,7 +75,7 @@ const iterate = async (select: HTMLSelectElement | null, afterEach?: () => any)
 
       if (dimensions && (offsetSizeChanged || dirChanged)) {
         await waitFor(
-          async () => {
+          () => {
             if (offsetSizeChanged) {
               should.equal(sizeIterations, currSizeIterations + 1);
             }
diff --git a/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.browser.ts b/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.browser.ts
new file mode 100644
index 0000000..bdfbbf5
--- /dev/null
+++ b/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.browser.ts
@@ -0,0 +1,141 @@
+import 'overlayscrollbars.scss';
+import './index.scss';
+import should from 'should';
+import { waitFor } from '@testing-library/dom';
+import { generateSelectCallback, iterateSelect, selectOption } from '@/testing-browser/Select';
+import { timeout } from '@/testing-browser/timeout';
+import { setTestResult } from '@/testing-browser/TestResult';
+import { offsetSize } from 'support';
+
+import { createTrinsicObserver } from 'overlayscrollbars/observers/TrinsicObserver';
+
+const waitForOptions = {
+  onTimeout(error: Error): Error {
+    setTestResult(false);
+    return error;
+  },
+};
+
+let heightIterations = 0;
+let heightIntrinsicCache: boolean;
+const envElm = document.querySelector('#env');
+const targetElm = document.querySelector('#target');
+const checkElm = document.querySelector('#check');
+const envHeightSelect: HTMLSelectElement | null = document.querySelector('#envHeight');
+const targetHeightSelect: HTMLSelectElement | null = document.querySelector('#targetHeight');
+const displaySelect: HTMLSelectElement | null = document.querySelector('#display');
+const startBtn: HTMLButtonElement | null = document.querySelector('#start');
+const changesSlot: HTMLButtonElement | null = document.querySelector('#changes');
+
+const envElmSelectCallback = generateSelectCallback(envElm as HTMLElement);
+const targetElmSelectCallback = generateSelectCallback(targetElm as HTMLElement);
+
+envHeightSelect?.addEventListener('change', envElmSelectCallback);
+targetHeightSelect?.addEventListener('change', targetElmSelectCallback);
+displaySelect?.addEventListener('change', targetElmSelectCallback);
+
+envElmSelectCallback(envHeightSelect);
+targetElmSelectCallback(targetHeightSelect);
+targetElmSelectCallback(displaySelect);
+
+const iterate = async (select: HTMLSelectElement | null, afterEach?: () => any) => {
+  interface IterateSelect {
+    currHeightIterations: number;
+    currHeightIntrinsic: boolean;
+  }
+
+  await iterateSelect<IterateSelect>(select, {
+    beforeEach() {
+      const currHeightIterations = heightIterations;
+      const currHeightIntrinsic = offsetSize(checkElm as HTMLElement).h === 0;
+      return {
+        currHeightIterations,
+        currHeightIntrinsic,
+      };
+    },
+    async check({ currHeightIterations, currHeightIntrinsic }) {
+      const newHeightIntrinsic = offsetSize(checkElm as HTMLElement).h === 0;
+      const trinsicHeightChanged = newHeightIntrinsic !== currHeightIntrinsic;
+
+      await waitFor(() => {
+        if (trinsicHeightChanged) {
+          should.equal(heightIterations, currHeightIterations + 1);
+        }
+      }, waitForOptions);
+    },
+    afterEach,
+  });
+};
+
+const iterateEnvHeight = async (afterEach?: () => any) => {
+  await iterate(envHeightSelect, afterEach);
+};
+const iterateTargetHeight = async (afterEach?: () => any) => {
+  await iterate(targetHeightSelect, afterEach);
+};
+const changeWhileHidden = async () => {
+  selectOption(targetHeightSelect as HTMLSelectElement, 'targetHeightHundred');
+
+  const autoToHundred = async () => {
+    selectOption(envHeightSelect as HTMLSelectElement, 'envHeightAuto');
+    selectOption(displaySelect as HTMLSelectElement, 'displayNone');
+
+    await timeout(250);
+
+    selectOption(envHeightSelect as HTMLSelectElement, 'envHeightHundred');
+    selectOption(displaySelect as HTMLSelectElement, 'displayBlock');
+
+    await waitFor(() => {
+      should.equal(heightIntrinsicCache, false);
+    }, waitForOptions);
+  };
+
+  const hundredToAuto = async () => {
+    selectOption(envHeightSelect as HTMLSelectElement, 'envHeightHundred');
+    selectOption(displaySelect as HTMLSelectElement, 'displayNone');
+
+    await timeout(250);
+
+    selectOption(envHeightSelect as HTMLSelectElement, 'envHeightAuto');
+    selectOption(displaySelect as HTMLSelectElement, 'displayBlock');
+
+    await waitFor(() => {
+      should.equal(heightIntrinsicCache, true);
+    }, waitForOptions);
+  };
+
+  await autoToHundred();
+  await hundredToAuto();
+  await autoToHundred();
+  await hundredToAuto();
+};
+
+const start = async () => {
+  setTestResult(null);
+
+  targetElm?.removeAttribute('style');
+  await iterateEnvHeight();
+  await iterateTargetHeight();
+  await iterateEnvHeight(async () => {
+    await iterateTargetHeight();
+  });
+  await changeWhileHidden();
+
+  setTestResult(true);
+};
+
+startBtn?.addEventListener('click', start);
+
+createTrinsicObserver(targetElm as HTMLElement, (widthIntrinsic: boolean, heightIntrinsic: boolean) => {
+  if (heightIntrinsic !== heightIntrinsicCache) {
+    heightIterations += 1;
+    heightIntrinsicCache = heightIntrinsic;
+  }
+  requestAnimationFrame(() => {
+    if (changesSlot) {
+      changesSlot.textContent = heightIterations.toString();
+    }
+  });
+});
+
+export { start };
diff --git a/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.html b/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.html
new file mode 100644
index 0000000..e208a2d
--- /dev/null
+++ b/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.html
@@ -0,0 +1,31 @@
+<div id="controls">
+  <label for="display">display</label>
+  <select name="display" id="display">
+    <option value="displayBlock">block</option>
+    <option value="displayNone">none</option>
+  </select>
+  <label for="envHeight">envHeight</label>
+  <select name="envHeight" id="envHeight">
+    <option value="envHeightAuto">auto</option>
+    <option value="envHeightHundred">100%</option>
+    <option value="envHeight200">200px</option>
+  </select>
+  <label for="targetHeight">targetHeight</label>
+  <select name="targetHeight" id="targetHeight">
+    <option value="targetHeightAuto">auto</option>
+    <option value="targetHeightHundred">100%</option>
+    <option value="targetHeight200">200px</option>
+  </select>
+
+  <button id="start">start</button>
+  <span>Detected changes: <span id="changes">0</span></span>
+</div>
+<div id="stage">
+  <div>
+    <div id="env">
+      <div id="target">
+        <div id="check"></div>
+      </div>
+    </div>
+  </div>
+</div>
diff --git a/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.scss b/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.scss
new file mode 100644
index 0000000..5f44e4c
--- /dev/null
+++ b/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.scss
@@ -0,0 +1,67 @@
+body {
+  display: flex;
+  flex-direction: column;
+}
+#controls {
+  flex: none;
+}
+#stage {
+  flex: auto;
+  position: relative;
+
+  & > div {
+    position: absolute;
+    top: 0;
+    right: 0;
+    bottom: 0;
+    left: 0;
+    background: lightgoldenrodyellow;
+  }
+}
+
+#canvas > div {
+  position: absolute;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  left: 0;
+}
+
+#env {
+  background: rgba(0, 0, 0, 0.3);
+}
+
+#target {
+  background: rgba(0, 0, 0, 0.3);
+  overflow: hidden;
+  position: relative;
+  // prevent container from reaching 0x0 dimensions for testing purposes
+  min-width: 50px;
+  min-height: 50px;
+}
+
+#check {
+  height: 100%;
+}
+
+.envHeightAuto,
+.targetHeightAuto {
+  height: auto;
+}
+
+.envHeight200,
+.targetHeight200 {
+  height: 200px;
+}
+
+.envHeightHundred,
+.targetHeightHundred {
+  height: 100%;
+}
+
+.displayNone {
+  display: none;
+}
+.displayBlock {
+  display: block;
+}
diff --git a/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.test.ts b/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.test.ts
new file mode 100644
index 0000000..0d2ffb1
--- /dev/null
+++ b/packages/overlayscrollbars/tests/puppeteer/TrinsicObserver/index.test.ts
@@ -0,0 +1,15 @@
+import expectPuppeteer from 'expect-puppeteer';
+import url from './.build/build.html';
+
+describe('Environment', () => {
+  beforeAll(async () => {
+    await page.goto(url);
+  });
+
+  it('test', async () => {
+    await expectPuppeteer(page).toClick('#start');
+    await expectPuppeteer(page).toMatchElement('#testResult.passed', {
+      timeout: 60000,
+    });
+  }, 60000);
+});