Čuvajte zapešće tako što koristite podlogu za miš.

That ending marks the imperative form for you plural or formal you singular.

So:

• čuvaj = protect! / take care! (to one person, informal)
• čuvajte = protect! / take care! (to several people, or to one person politely)

This is very common in instructions, warnings, and polite advice.

It can be either:

• one person politely
• more than one person

Croatian uses the same form, čuvajte, for both. In a safety notice or instruction, this often sounds like a polite general recommendation to the reader.

Croatian often leaves out possessive words like your when they are obvious from context, especially with body parts.

So Čuvajte zapešće naturally means Protect your wrist.

This is similar to other common Croatian expressions like:

• Operite ruke. = Wash your hands.
• Zatvorite oči. = Close your eyes.

Adding svoje is possible, but it is often unnecessary here.

It actually is in the correct case already. After čuvajte, zapešće is the direct object, so it should be in the accusative.

The reason it looks unchanged is that zapešće is a neuter singular noun, and for this noun the nominative and accusative singular have the same form:

• nominative: zapešće
• accusative: zapešće

So the case is different in function, but not in visible form.

Tako što means by, by doing so, or more literally in such a way that.

In this sentence, it introduces the method:

• Čuvajte zapešće tako što koristite...
• Protect your wrist by using...

It is a very useful Croatian pattern for explaining how something is done.

After tako što, Croatian commonly uses a normal finite verb form, where English would often use by + -ing.

So:

• tako što koristite podlogu za miš
• literally: by the fact that you use a mouse pad
• natural English: by using a mouse pad

A useful thing to notice is that koristite has the same shape as you use and use! for plural/formal you, but here after tako što it functions as part of the by doing... construction.

Because podlogu is the accusative singular form of podloga.

The verb koristiti takes a direct object, so the noun has to go into the accusative:

• nominative: podloga
• accusative: podlogu

This is a very common pattern with feminine nouns ending in -a:

• knjiga → knjigu
• torba → torbu
• podloga → podlogu

The preposition za here means for and takes the accusative.

With miš meaning computer mouse, Croatian usually treats it as inanimate, so the accusative is the same as the nominative:

• nominative: miš
• accusative: miš

If you were talking about an actual animal mouse, you would normally expect miša in the accusative because that noun is animate.

So in this sentence:

• podloga za miš = mouse pad
• literally: pad for a mouse

Yes. Podloga za miš is a normal and clear Croatian term for mouse pad.

Literally it means:

• podloga = pad, mat, base, support
• za miš = for a mouse

So the whole phrase works exactly like a practical descriptive term: a pad for a mouse.

Yes. Zaštitite zapešće would also be correct and may sound even more directly like Protect the/your wrist.

The difference is roughly this:

• čuvati = to protect, take care of, keep safe
• zaštititi = to protect, shield

In advice or instructions, both can work. The original sentence is perfectly natural, but zaštitite would be another good option.