Holiness by elevating deeds to their root

ובמד' ואתה מרום רוממות אתה נוהג בעולמך.

And in the Midrash: "And You are exalted (marom)" — You conduct Your world through exaltation (romemus).

The Midrash reads "marom" as teaching that Hashem governs His world specifically by means of "lifting up" — through an aspect of elevation rather than through nature alone.

הוא כנ"ל שהקב"ה עשה להיות הנהגות כל הבריאה ע"י זה התרוממות שמרימין המעשים לכח השורש שלמעלה מהטבע שנק' מרום עי"ז יש להם קיום וז"ש רוממות אתה נוהג כו'.

This is as explained above: that the Holy One arranged the governance of all creation to come about through this elevation — that the deeds are raised up to the power of the root that is above nature, which is called "marom (the heights)" — and through this they gain endurance. And this is the meaning of "through exaltation You conduct [Your world]."

Hashem set up the world so that all of creation is sustained by being elevated. When our deeds are lifted up to their source-root above nature — called "marom" — they receive lasting existence. That elevation is the very means by which Hashem runs His world.

וז"ש קדושים תהיו כי קדוש א"ה אלקיכם פי' שכוחות שלכם דבקים בי ומצד זה אתם יכולים להתקדש כנ"ל:

And this is the meaning of "You shall be holy (kedoshim tihyu), for I, Hashem your God, am holy" — meaning that your powers are attached (deveikim) to Me, and on account of this you are able to become holy, as explained.

The verse grounds our potential for kedushah in Hashem's own holiness: because the powers within you are bound to and rooted in Me, you are able to elevate and sanctify them. Your capacity to be holy flows from your essential connection to the holy Source above nature.

Summary: Hashem conducts His world through "romemus" — elevation — sustaining all of creation by raising deeds up to their root-source above nature, called "marom." This is the meaning of "kedoshim tihyu, for I am holy": because our very powers are bound (deveikim) to Hashem, the holy Source, we are able to elevate and sanctify them, drawing endurance and kedushah from above nature.