About this heart symbol
There are two kinds of heart in Unicode and the difference matters. The text hearts, ♥ (U+2665, the card suit) and ♡ (U+2661, its hollow twin), behave like letters: they take on the size and color of the surrounding text, so a heart in a red headline comes out red. The emoji hearts, ❤️ and the colored family around it, are drawn by your platform in its own artwork, which is why the same message can look different on a phone and a laptop. If you want a heart that matches your typography, take a text heart. If you want the familiar chat heart, take an emoji one. A quirk worth knowing: ❤ (U+2764) is a text character by default, and the invisible variation selector after it is what makes most platforms render the emoji version, which is why pasting it sometimes gives a black outline instead of a red heart.