Adjusting size of background image in Soho Theme

I would like to reduce the height of the background image on blogger - in the Soho Theme. There is not adjustment (slider, etc) for this. I did come across a CSS to add, this is what I added as a CSS:

<style>
.hero-image.has-image {
max-height:25vh!important;
min-height:10vh!important;
}
</style>

Reference Links

• Adjusting size of background image in Soho Theme - Blogger Help
• [筆記] 好用的css 3新單位vh vw ─ 讓你的圖片可以隨著螢幕大小 ...
• 7個你可能不認識的CSS單位:rem vh vw vmin vmax ex ch - IT閱讀