Sure, let's create a simple "Hello World" HTML/CSS project. The project will consist of two files: an HTML file and a CSS file.
index.html
```
Hello World
Hello World
```
styles.css
```
.center-text {
text-align: center;
color: blue;
font-size: 2em;
}
```
In the HTML file, we have a basic structure of an HTML document. The `` tag includes a `` tag to set the title of the webpage and a `<link>` tag to link the CSS file to the HTML file.
In the `<body>` tag, we have an `<h1>` tag with the text "Hello World". This tag has a class attribute set to "center-text", which we will define in the CSS file.
In the CSS file, we define the "center-text" class. We set the text alignment to center, the color to blue, and the font size to 2em (twice the size of the current font).
This concludes a fully working implementation.