Hi there! My name is Karin and I will take a review your code today 😊

Nice with a custom font! 😊👍

Using rgb-values are perfectly fine, but it's more common to use hex-values, for example #ffffff = white. There is also an option to use rgba(xx, xx, xx, AA), where AA stands for alpha (opacity). And don't forget about the semi-colons at the end! 😊😊

If you want to target the p-tag only, the paragraph, you don't need to use a class name for it. :) All you need is p, without a dot or anything else, like so:

p {
....
}

If you want "Reenie Beanie" applied to the entire page, you could put it on the body-tag, and specify if you want a different font wherever you want it. 😊

Like this:

body {
    font-family: "Reenie Beanie";
}

.some-other-class {
    font-family: "Some other font";
}

I'm not sure what these three rows are doing, but I think another way going about this would be to use flexbox, and having the box model in mind. 😄 I would also recommend using a class instead of an id for this. 👍🏻 For example, you could put the following on this tag:

.galerie {
    // will set the wrapper-box to full width
    width: 100%;

     // These three rows sets the display to flex, and place all content in the center
    display: flex;
    align-items: center; 
    justify-content: center; 

    // When you've assigned a width to all divs in this wrapper, you'll have to use flex to make 
    // the fourth box move down to the second row.
    flex-wrap: wrap; 
}

....

To make the font cursive and changing size/line height, you'll have to write like this:

font-style: italic;
font-size: 10px;
line-height: 150%;

This is great! Looks super nice! 🌟

If you want, you could separate the background-image source from the other settings into two classes, to avoid having to repeat the same settings every time. 😊

For example:
<div class="parallaxwir"></div>
could instead be:
<div class="parallax wir"></div>

and the styling would look like this:

.parallax {
        min-height: 60vh;
	background-position: center;
	background-repeat: no-repeat;
	background-size: cover;
        background-attachment: fixed;
}

.wir {
	background-image: url("images/LaaxSkipiste.jpg");
}

By doing like this, you would only have to add more source-classes if you want the image to be different. 👌

For example:
<div class="parallax plan"></div>
+

.plan {
	background-image: url("images/other-image.jpg");
}

Very good usage of semantic HTML-tags! 🌟

You should try to add some indentation to your code, to make it easier to read. 😊