"The door of my house is white."
Translation:La puerta de mi casa es blanca.
I made the mistake of putting in 'el puerto', which is of course: the harbour.
Try making the mistake of putting in "La porta" which is the Catalan translation :(
The door is white and will probably stay that way. Esta is for non permanent things. The lamp might be on the table for now. Until someone moves it or it gets knocked over etc.
Also, "La lamapara esta sobre la mesa" is indicating location of an object, and so uses 'estar'.
'De color' is unnecessary. If you use the adjective blanca then you are obviously describing the color of something. You could use this structure sometimes, especially when your phrase is something like 'painted white.'
The biggest problem with your choice of words though is that your phrase uses 'white' as a noun (the name of a color is a noun). The adjective 'white' (blanco or blanca) matches the gender of the noun, but the name of the color is always blanco. Color names don't change for another noun's gender because color names are nouns. Nouns already have their own gender.
So- “La puerta es blanca."
But- “La puerta está pintada de blanco."
Why not La puerta de LA mi casa es blanca?
Is feminime de mi casa: of my house and de la mi casa: of the my house?
Otherwise im lost here
“De la mi casa" makes as little sense in Spanish as “of the my house" does in English. In case you're not an English native, I'm saying that makes no sense at all.