Hi Brother,
I think a better way to do this if meant to used in the postbit is to use custom BBCODE.
First we need to define the custom bbcode.
Step 1:
Go to--->ACP--->Custom BB Codes--->Add new BBcode.
Title: BBcode Image display in mobile only
BB Code Tag Name: IMGmobile
Replacement:
Code:
<img class="imgshowonmobile" src="{param}" border="0" />
Example: [IMGmobile]You Image link[/IMGmobile]
Description: Image display on mobile only.
Use {option}: No
Click SAVE BBcode.
Step 2:
Go to--->ACP--->Styles & Templates--->Style Manager--->You Styles--->Main CSS--->Additional CSS Definitions
add this Code on the bottom of the window last
HTML Code:
html.range_0 .imgshowonmobile,
html.range_1 .imgshowonmobile,
html.range_2 .imgshowonmobile,
html.range_3 .imgshowonmobile{display:block}
html.range_4 .imgshowonmobile,
html.range_5 .imgshowonmobile{display:none}