About the Wave effect
The Wave background draws two independent sine curves across the screen, one with tilde characters (~) and one with double tildes (≈). Each curve has its own wavelength and speed, so the lines cross, separate and meet again without ever repeating in an obvious rhythm. Most of the canvas stays empty, which is what makes this effect so easy to put behind text: there is motion at the edge of your attention, but nothing competes with a headline or a call to action. Because the shape is computed per column from the viewport width, the wave fills any screen size without stretching. Slow it down to 0.3× for a meditative screensaver feel, or push it toward 2× for a choppier sea. A cool color such as cyan or blue suits the water theme, while green keeps the classic terminal look.