Regular Expressions 101

Explanation
Pro

Group 1(<h4 class="sumary-title">.+\n.+)

<h4 class="sumary-title">the literal text <h4 class="sumary-title"> (case insensitive)

.+any character (except for line terminators), repeated at least once

\na line-feed (newline) character (ASCII 10)

.+any character (except for line terminators), repeated at least once

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Detailed match information will be displayed here automatically.

26 tokens

(<h4 class="sumary-title">.+\n.+)

New

<div class="sumary">\n$1</div>