Underline CSS button
Minimal button with a thick bottom border. Hover, click and tab to it to see every state.
CSS
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&display=swap');
.btn {
display: inline-flex;
align-items: center;
justify-content: center;
gap: .5em;
padding: 8px 6px;
font-family: 'Inter', sans-serif;
font-size: 16px;
font-weight: 600;
line-height: 1.2;
color: #0f172a;
background: rgba(255, 255, 255, 0);
border: 0;
border-radius: 0px;
box-shadow: inset 0 -3px 0 0 #6366f1;
cursor: pointer;
text-decoration: none;
white-space: nowrap;
-webkit-tap-highlight-color: transparent;
transition: transform 200ms cubic-bezier(.2,.8,.2,1), box-shadow 200ms cubic-bezier(.2,.8,.2,1), filter 200ms cubic-bezier(.2,.8,.2,1);
}
.btn__icon {
display: inline-block;
transition: transform 200ms cubic-bezier(.2,.8,.2,1);
}
.btn:hover .btn__icon {
transform: translateX(3px);
}
.btn:active {
transform: translateY(1px) scale(0.979999999999999982236431605997495353221893310546875);
transition-duration: 100ms;
}
.btn:focus-visible {
outline: 3px solid #0f172a;
outline-offset: 3px;
}
@media (prefers-reduced-motion: reduce) {
.btn,
.btn__icon {
transition: none;
animation: none;
}
}HTML
<button class="btn" type="button">
Continue
<span class="btn__icon" aria-hidden="true">→</span>
</button>How this button is built
- Background: transparent, so the button takes the colour of whatever is behind it.
- Type: Inter, weight 600, 16px, in #0f172a.
- Shape: square corners with 8px × 6px padding.
- Depth: an inset highlight along the edge.
- Interaction: on hover it nudges its icon, and it squishes slightly when clicked, with 200ms transitions.
- Accessibility: a visible
:focus-visiblering for keyboard users, and all motion turns off underprefers-reduced-motion.
How to use it
- Copy the CSS into your stylesheet. The
@importline loads the Inter font from Google Fonts. Move it to the top of your file, or drop it if you already load the font. - Paste the HTML where you want the button. It works on
<button>,<a>and<input type="submit">. - Change the label, or rename the
.btnclass if it clashes with your framework. Want a different colour or size? Open it in the editor, change it visually, and copy the new code.