Unable to replace the default search icon using CSS

I tried to replace the default search icon in the search box by using the following code

.ms-InlineSearch-DivBaseline .ms-InlineSearch-Outline-Baseline .ms-inlineSearch-searchImgSpanBase > img{ background-image:url('Icons/custom-icon.png') !important ; background-repeat:no-repeat; display:block; }

Image tag has an inline styling with src="location of default image",and it is not allowing to override the CSS even with !important specified. How can we change the default icon with our custom icon. Note: Targeting the img tag is correct as I applied display:none,it did hid the default image.