Is there a word that captures the following meaning?
"Neither modern nor outdated. Mature and stable."
For example, if this word were X, then we could apply it to a technology like television or a branch of study like science because they are mature and stable. Neither is exactly too modern. However, we could not apply this word to say smartphones or electric cars because they are pretty modern. They may be stable too but they are modern and so they are ruled out.
Here are some example usages of this word:
Television is an X piece of technology.
I love web browsers because they are X.