I find the trouble but still not know how to resolve that issue better:
The code will display right before the closing </head> tag. Include <script> for JS and <style> for CSS.
I put the code under: Tracking Code
Paste your tracking code here. This will be added into the header section of your template.
<!-- Global site tag (gtag.js) - Google Analytics -->
<script async src="www.googletagmanager.com/gtag/js?id=UA-120837267-1"></script>
window.dataLayer = window.dataLayer || ;
gtag('js', new Date());
<!-- End Global site tag (gtag.js) - Google Analytics -->
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