regex101: Select Topmost HTML Tags

Regular Expression

\<(ol)(?: .*?)?\>(?:[^\<]|\<(.*?)\>.*\<\/\2\>)*\<\/\1\>

<ol>kjkjkj

</ol>



<ol s>
        <li>Table of Contents.....................CT.TS</li>
        <li>Gamecube Controls.....................CN.GC</li>
        <li>Nintendo 64 Controls..................CN.64</li>
        <li>Walkthrough...........................01.00
            <ol>
                <li>Kokiri Forest...............01.01</li>
            </ol>
        </li>    
        <li>Sidequests &amp; Minigames................02.00
            <ol>
                <li>Shooting Gallery............02.01</li>
            </ol>
        </li>
        <li>Boss Guide............................03.00
            <ol>
                <li>Gohma.......................03.01</li>
                <li>Final Boss [Second Form]....03.15</li>
            </ol>
        </li>
        <li>Item Checklist........................04.00
            <ol>
                <li>Final Dungeon...............04.47</li>
            </ol>
        </li>
        <li>Shop Inventory........................05.00            
            <ol>
                <li>Kokiri Shop [Young].........05.01</li>
                <li>Goron Shop [Adult]..........05.09</li>
            </ol>
        </li>
        <li>Ocarina Notes.........................06.00
            <ol><ol>sdsds</ol>
                <li>Requ<ol></ol>iem of Spirit...........06.12</li>
            </ol>
        </li>
        <li>Heart Containers......................07.00</li>
        <li>Item List.............................15.00</li>
        <li>Legal &amp; Copyright.....................LE.AL</li>
        <li>Credits &amp; Thanks......................CR.DS</li>
    </ol>

<ol><ol><ol><ol><ol></ol></ol></ol></ol></ol>


sdsd
k<ol>jlkjlkj 
kjbkjh</ol>

Substitution

<ol>kjkjkj

</ol>



<ol s>
        <li>Table of Contents.....................CT.TS</li>
        <li>Gamecube Controls.....................CN.GC</li>
        <li>Nintendo 64 Controls..................CN.64</li>
        <li>Walkthrough...........................01.00
            <ol>
                <li>Kokiri Forest...............01.01</li>
            </ol>
        </li>    
        <li>Sidequests &amp; Minigames................02.00
            <ol>
                <li>Shooting Gallery............02.01</li>
            </ol>
        </li>
        <li>Boss Guide............................03.00
            <ol>
                <li>Gohma.......................03.01</li>
                <li>Final Boss [Second Form]....03.15</li>
            </ol>
        </li>
        <li>Item Checklist........................04.00
            <ol>
                <li>Final Dungeon...............04.47</li>
            </ol>
        </li>
        <li>Shop Inventory........................05.00            
            <ol>
                <li>Kokiri Shop [Young].........05.01</li>
                <li>Goron Shop [Adult]..........05.09</li>
            </ol>
        </li>
        <li>Ocarina Notes.........................06.00
            <ol><ol>sdsds</ol>
                <li>Requ<ol></ol>iem of Spirit...........06.12</li>
            </ol>
        </li>
        <li>Heart Containers......................07.00</li>
        <li>Item List.............................15.00</li>
        <li>Legal &amp; Copyright.....................LE.AL</li>
        <li>Credits &amp; Thanks......................CR.DS</li>
    </ol>

<ol><ol><ol><ol><ol></ol></ol></ol></ol></ol>


sdsd
k<ol>jlkjlkj 
kjbkjh</ol>