Remove blank spaces between buttons in HTML, CSS

Question

I want to remove blank spaces between the buttons, so that when I for example hover over the NORMAL button, there will be no blank space between it and the HARD button. How can I do that and where do these blank spaces come from?

body {
  margin: 0;
}
#stripe {
    background-color: white;
    text-align: center;
    height: 50px;
    color: black;
}

button {
    border: none;
    background: none;
    text-transform: uppercase;
    height: 100%;
    font-weight: 700;
    color: black;
    letter-spacing: 1px;
    font-size: inherit;
    transition: all 0.3s;
    outline: none;
}

button:hover {
    color: white;
    background: black;
}

.selected {
    color: white;
    background: black;
}

<div id="stripe">
    <button class="mode">Easy</button>
    <button class="mode">Normal</button>
    <button class="mode selected">Hard</button>
</div>

Answer 1

Browsers always add spaces between some elements, including buttons. To remove these, you need to set font-size to zero for their parent container. Then, to restore text size inside buttons, set font-size for them.

#stripe {
  font-size: 0;
}

button {
  font-size: 14px; // Set font size that you need here
}