Why do you not play in fullscreen? There is a button on lower right corner.
Or you can zoom the page in maybe, so the thing gets scrolled away.
And you can always inspect the element with right click and then right click the line and select hide, so it is not visible anymore.
Compared to similar games, the games is worth the money.
This is demo version and they changed game play several times. Like the curses and money and how certain items work. And I guess it might change several times till full release.
I do not know what to expect from announced story mode. The thing to aspire to with Slay the Spire was actually be able to beat the boss after the endboss. The level structure is basically exactly the same as with StS. But here after 3rd boss there is endless mode. You might wanna check out the discord for more current information on what is happening or being planned for the story mode.