How can i run html programme in opera browser

Question

do i need to write a programme two time and with every line i need to write-O-

Answer 1

Opera hasn't used the "o" vendor prefix since ~2013 (when it switched to "webkit").
Vendor prefixes are discouraged by the industry (because of heavy misuse) and they are being moved to "flags" so that websites can no longer misuse them.

To avoid the need to change unprefixed code when supporting older browsers, a library like "prefixfree" lets you use standard CSS and automatically injects prefixes (only when required):
https://leaverou.github.io/prefixfree/
I believe prefixfree handles Opera back to version 10 (2009).

Please note that vendor prefixes identify features that were not yet approved for production use in the affected browser (so results may vary).

Answer 2

Thankyou very much

Answer 3

Nope html can be opened in opera as well as in any other browser