Question: In the following code (<https://jsfiddle.net/6t9n0wuu/>):

```css
#cont1 {
  width: 50%
}

#div1 {
  width: 10px;
  float: left;
  border: 1px solid black
}

#div2 {
  float: left;
  border: 1px solid black
}
```

```html
<div id=cont1>
  <div id=div1>a<br>b<br>c<br></div>
  <div id=div2>
    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
    in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
  </div>
</div>
```

the content of `div2` is shifted to a new line. 

Is it possible to force `div2` on the top as (i.e. on the same line of) `div1` without specifing its width in CSS?

Answer: 
No, you can not. Without the width specified one way or another the float will take all the space it needs to display its content. Since its contents is some text it will always shift to another line unless the text width is less then the remaining width of the line. Notice that even if you manage to modify content so that it all fits into one line, once you change the size of the container, e.g. by resizing the window, the float can be moved to another line again.

Thus, your options are:

1. Specify the width, using px, %, calc, whatever.
2. Use some other layout design: e.g. flexbox or grid (check if all the
browsers you have to support work with them)
3. Use table if what you you want to display is actually some table
data.
4. Don't try to squeeze everything into one row.
```css
#cont1 {width: 50%; display:flex;}
#div1 {width:10px;float:left; border:1px solid black}
#div2 { border:1px solid black}
```

```html
<div id=cont1>
<div id=div1>a<br>b<br>c<br></div>
<div id=div2>
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
</div>
</div>
```