# Approach
There is a clue to the flag in the task description: `Nothing has worked so far but we have noticed a weird comment in the HTML.`

When we inspect the website's element, we will find a hidden element:
```html
<div style="display: none;">Need to remove flagstuff. code: G1v3M3Th3Fl@g!!!!</div>
```

Just above that, there's a `div` tag:
```html
<div id="flagstuff" code=""></div>
```

It turns out that we need to fill in the `code` to the `div` tag. So, change the `div` tag to something like this:
```html
<div id="flagstuff" code="G1v3M3Th3Fl@g!!!!"></div>
```

Then, we only need to type in at the provided `textarea`.

# Answer

- Flag: `swampCTF{Cr0ss_S1t3_Scr1pt1ng_0r_XSS_c4n_ch4ng3_w3bs1t3s}`