Question: I have a data in following format:

```

ID  time0       obs_num recorded_dt 
1   2009-01-01  A       2009-01-01  
1   2009-01-01  D       2009-01-31  
1   2009-01-01  B       2009-01-05  
2   2005-02-02  B       2005-02-03  

```

I want to calculate columns based on days difference for up to a month in reference to time0 and add respective values from the obs\_num column. In the end, the data should look like this:

```

ID  time0       obs_num recorded_dt day0    day1    day2    day3    day4    day5    ... day31
1   2009-01-01  A       2009-01-01  A       NULL    NULL    NULL    NULL    NULL    ... NULL
1   2009-01-01  D       2009-01-31  NULL    NULL    NULL    NULL    NULL    NULL    ... D
1   2009-01-01  B       2009-01-05  NULL    NULL    NULL    NULL    NULL    B       ... NULL
2   2005-02-02  B       2005-02-03  NULL    B       NULL    NULL    NULL    NULL    ... NULL

```

Answer: 
The reason why your anchor tags are not working is a combination of using `display: inline;` styles and `position: absolute;`. To fix this issue, update your styles to be accurate to [this](https://jsfiddle.net/x7jnLpue/3/) JSFiddle. I have also corrected some of your syntax.
1. using `div` in `a` tag is semantically incorrect. You should use `span` tag.
2. don't use `li` in `a` tag. Use `a` in `li` tag.
3. if you want to use `div` in `a` tag just use:

```
<div style="cursor: pointer;" onclick="window.location='http://google.com';">
Hello world
</div>

```

or use:

```
<a href="http://google.com">
    <span style="display: block;">
        Hello world
    </span>
</a>

```

```html
<header>
        <div class="logo">
        <a href=""><img src="https://media.istockphoto.com/vectors/abstract-business-arrow-up-logo-icon-vector-design-template-vector-id1140553971?k=20&m=1140553971&s=612x612&w=0&h=7-a1JjWAf8c5qKF46FRgdFg-3jva9qo80hqh0z_Y34A=" alt="Samsung Logo" width="150"></a>
        <ul class="menubalk">
            <li><a href="#">Contact</a></li>
            <li><a href="#assortiment-scroll">Assortiment</a></li>
        </ul>
    </div>
</header>

<div class="bg">
        <video src="videos/S22-Ultra-unboxing.mp4" muted loop autoplay></video>
        <div class="bg-text">Nieuwe S22 Ultra</div>
        <a href="#"><span class="bg-text-url">Discover</span></a>
</div>
```