CSS Animated Underline Tabs Navbar
Tab-style navbar with an animated bottom border that slides between items using CSS transitions and radio-button state.
Published
The code
<div class="nav-04">
<input type="checkbox" id="nav-04-toggle">
<div class="nav-04__top">
<a href="#" class="nav-04__logo">Stack<span>.</span></a>
<div class="nav-04__spacer"></div>
<div class="nav-04__actions">
<a href="#" class="nav-04__action-link">Sign in</a>
<button class="nav-04__btn">Start building</button>
</div>
<label for="nav-04-toggle" class="nav-04__hamburger" aria-label="Toggle menu">
<span></span><span></span><span></span>
</label>
</div>
<div class="nav-04__tabs">
<a href="#" class="nav-04__tab is-active">Overview</a>
<a href="#" class="nav-04__tab">Components <span class="nav-04__tab-count">48</span></a>
<a href="#" class="nav-04__tab">Templates <span class="nav-04__tab-count">12</span></a>
<a href="#" class="nav-04__tab">Documentation</a>
<a href="#" class="nav-04__tab">Changelog <span class="nav-04__tab-count">3</span></a>
<a href="#" class="nav-04__tab">Community</a>
<a href="#" class="nav-04__tab">Showcase</a>
</div>
<div class="nav-04__mobile">
<a href="#">Overview</a>
<a href="#">Components</a>
<a href="#">Templates</a>
<a href="#">Documentation</a>
<a href="#">Changelog</a>
<a href="#">Community</a>
<a href="#">Showcase</a>
</div>
</div>
<div style="padding:4rem 2.5rem; max-width:700px; margin:0 auto;">
<h1 style="font-size:2.5rem; font-weight:800; letter-spacing:-0.04em; margin-bottom:1rem;">Animated Underline <span style="color:#ff6b35;">Tabs Navbar</span></h1>
<p style="color:#888; font-size:1.1rem; line-height:1.7;">The sliding underline is a <code>scaleX</code> transform on an <code>::after</code> pseudo-element. Hover shows a 60% preview; active tab shows 100% width. No JavaScript.</p>
</div><div class="nav-04">
<input type="checkbox" id="nav-04-toggle">
<div class="nav-04__top">
<a href="#" class="nav-04__logo">Stack<span>.</span></a>
<div class="nav-04__spacer"></div>
<div class="nav-04__actions">
<a href="#" class="nav-04__action-link">Sign in</a>
<button class="nav-04__btn">Start building</button>
</div>
<label for="nav-04-toggle" class="nav-04__hamburger" aria-label="Toggle menu">
<span></span><span></span><span></span>
</label>
</div>
<div class="nav-04__tabs">
<a href="#" class="nav-04__tab is-active">Overview</a>
<a href="#" class="nav-04__tab">Components <span class="nav-04__tab-count">48</span></a>
<a href="#" class="nav-04__tab">Templates <span class="nav-04__tab-count">12</span></a>
<a href="#" class="nav-04__tab">Documentation</a>
<a href="#" class="nav-04__tab">Changelog <span class="nav-04__tab-count">3</span></a>
<a href="#" class="nav-04__tab">Community</a>
<a href="#" class="nav-04__tab">Showcase</a>
</div>
<div class="nav-04__mobile">
<a href="#">Overview</a>
<a href="#">Components</a>
<a href="#">Templates</a>
<a href="#">Documentation</a>
<a href="#">Changelog</a>
<a href="#">Community</a>
<a href="#">Showcase</a>
</div>
</div>
<div style="padding:4rem 2.5rem; max-width:700px; margin:0 auto;">
<h1 style="font-size:2.5rem; font-weight:800; letter-spacing:-0.04em; margin-bottom:1rem;">Animated Underline <span style="color:#ff6b35;">Tabs Navbar</span></h1>
<p style="color:#888; font-size:1.1rem; line-height:1.7;">The sliding underline is a <code>scaleX</code> transform on an <code>::after</code> pseudo-element. Hover shows a 60% preview; active tab shows 100% width. No JavaScript.</p>
</div>.nav-04,
.nav-04 *,
.nav-04 *::before,
.nav-04 *::after {
margin: 0;
padding: 0;
box-sizing: border-box;
}
.nav-04 {
--bg: #fff;
--text: #1c1c1c;
--muted: #888;
--accent: #ff6b35;
--track: #f0ebe3;
font-family: 'Manrope', sans-serif;
background: var(--bg);
border-bottom: 1px solid #f0ebe3;
position: sticky;
top: 0;
z-index: 100;
}
.nav-04__top {
display: flex;
align-items: center;
padding: 0 2.5rem;
height: 60px;
gap: 2rem;
}
.nav-04__logo {
font-weight: 800;
font-size: 1.25rem;
color: var(--text);
text-decoration: none;
letter-spacing: -0.04em;
flex-shrink: 0;
}
.nav-04__logo span {
color: var(--accent);
}
.nav-04__spacer {
flex: 1;
}
.nav-04__actions {
display: flex;
align-items: center;
gap: 0.75rem;
}
.nav-04__action-link {
font-size: 0.875rem;
font-weight: 600;
color: var(--muted);
text-decoration: none;
transition: color 0.2s;
}
.nav-04__action-link:hover {
color: var(--text);
}
.nav-04__btn {
padding: 0.45rem 1.1rem;
border-radius: 6px;
font-size: 0.875rem;
font-weight: 700;
cursor: pointer;
border: none;
font-family: inherit;
background: var(--text);
color: #fff;
transition: background 0.2s, transform 0.15s;
letter-spacing: -0.01em;
}
.nav-04__btn:hover {
background: var(--accent);
transform: translateY(-1px);
}
/* Tab nav */
.nav-04__tabs {
display: flex;
align-items: flex-end;
padding: 0 2.5rem;
overflow-x: auto;
scrollbar-width: none;
gap: 0;
height: 48px;
}
.nav-04__tabs::-webkit-scrollbar {
display: none;
}
.nav-04__tab {
flex-shrink: 0;
position: relative;
display: inline-flex;
align-items: center;
gap: 6px;
padding: 0 1.25rem;
height: 100%;
font-size: 0.875rem;
font-weight: 600;
color: var(--muted);
text-decoration: none;
transition: color 0.2s;
white-space: nowrap;
}
.nav-04__tab::after {
content: '';
position: absolute;
bottom: 0;
left: 0;
right: 0;
height: 2.5px;
background: var(--accent);
border-radius: 2px 2px 0 0;
transform: scaleX(0);
transition: transform 0.25s cubic-bezier(.4,0,.2,1);
}
.nav-04__tab:hover {
color: var(--text);
}
.nav-04__tab:hover::after {
transform: scaleX(0.6);
}
.nav-04__tab.is-active {
color: var(--accent);
}
.nav-04__tab.is-active::after {
transform: scaleX(1);
}
.nav-04__tab-count {
font-size: 0.7rem;
font-weight: 700;
background: var(--track);
color: var(--muted);
padding: 1px 6px;
border-radius: 10px;
min-width: 20px;
text-align: center;
}
.nav-04__tab.is-active .nav-04__tab-count {
background: #ffe8df;
color: var(--accent);
}
/* Mobile */
#nav-04-toggle {
display: none;
}
.nav-04__hamburger {
display: none;
flex-direction: column;
gap: 5px;
cursor: pointer;
padding: 8px;
border: none;
background: transparent;
}
.nav-04__hamburger span {
display: block;
width: 22px;
height: 2px;
background: var(--text);
border-radius: 2px;
transition: transform 0.3s, opacity 0.3s;
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(1) {
transform: translateY(7px) rotate(45deg);
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(2) {
opacity: 0;
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(3) {
transform: translateY(-7px) rotate(-45deg);
}
.nav-04__mobile {
display: none;
flex-direction: column;
gap: 0.25rem;
padding: 0.75rem 1.5rem 1rem;
border-top: 1px solid var(--track);
}
.nav-04__mobile a {
display: block;
padding: 0.6rem 0.5rem;
color: var(--text);
text-decoration: none;
font-weight: 600;
font-size: 0.95rem;
border-radius: 6px;
transition: background 0.15s, color 0.15s;
}
.nav-04__mobile a:hover {
background: #ffe8df;
color: var(--accent);
padding-left: 1rem;
}
#nav-04-toggle:checked ~ .nav-04__mobile {
display: flex;
}
@media (max-width: 640px) {
.nav-04__tabs,
.nav-04__actions {
display: none;
}
.nav-04__hamburger {
display: flex;
}
}
@media (prefers-reduced-motion: reduce) {
.nav-04__tab::after {
transition: none;
}
.nav-04__btn {
transition: none;
}
.nav-04__hamburger span {
transition: none;
}
}.nav-04,
.nav-04 *,
.nav-04 *::before,
.nav-04 *::after {
margin: 0;
padding: 0;
box-sizing: border-box;
}
.nav-04 {
--bg: #fff;
--text: #1c1c1c;
--muted: #888;
--accent: #ff6b35;
--track: #f0ebe3;
font-family: 'Manrope', sans-serif;
background: var(--bg);
border-bottom: 1px solid #f0ebe3;
position: sticky;
top: 0;
z-index: 100;
}
.nav-04__top {
display: flex;
align-items: center;
padding: 0 2.5rem;
height: 60px;
gap: 2rem;
}
.nav-04__logo {
font-weight: 800;
font-size: 1.25rem;
color: var(--text);
text-decoration: none;
letter-spacing: -0.04em;
flex-shrink: 0;
}
.nav-04__logo span {
color: var(--accent);
}
.nav-04__spacer {
flex: 1;
}
.nav-04__actions {
display: flex;
align-items: center;
gap: 0.75rem;
}
.nav-04__action-link {
font-size: 0.875rem;
font-weight: 600;
color: var(--muted);
text-decoration: none;
transition: color 0.2s;
}
.nav-04__action-link:hover {
color: var(--text);
}
.nav-04__btn {
padding: 0.45rem 1.1rem;
border-radius: 6px;
font-size: 0.875rem;
font-weight: 700;
cursor: pointer;
border: none;
font-family: inherit;
background: var(--text);
color: #fff;
transition: background 0.2s, transform 0.15s;
letter-spacing: -0.01em;
}
.nav-04__btn:hover {
background: var(--accent);
transform: translateY(-1px);
}
/* Tab nav */
.nav-04__tabs {
display: flex;
align-items: flex-end;
padding: 0 2.5rem;
overflow-x: auto;
scrollbar-width: none;
gap: 0;
height: 48px;
}
.nav-04__tabs::-webkit-scrollbar {
display: none;
}
.nav-04__tab {
flex-shrink: 0;
position: relative;
display: inline-flex;
align-items: center;
gap: 6px;
padding: 0 1.25rem;
height: 100%;
font-size: 0.875rem;
font-weight: 600;
color: var(--muted);
text-decoration: none;
transition: color 0.2s;
white-space: nowrap;
}
.nav-04__tab::after {
content: '';
position: absolute;
bottom: 0;
left: 0;
right: 0;
height: 2.5px;
background: var(--accent);
border-radius: 2px 2px 0 0;
transform: scaleX(0);
transition: transform 0.25s cubic-bezier(.4,0,.2,1);
}
.nav-04__tab:hover {
color: var(--text);
}
.nav-04__tab:hover::after {
transform: scaleX(0.6);
}
.nav-04__tab.is-active {
color: var(--accent);
}
.nav-04__tab.is-active::after {
transform: scaleX(1);
}
.nav-04__tab-count {
font-size: 0.7rem;
font-weight: 700;
background: var(--track);
color: var(--muted);
padding: 1px 6px;
border-radius: 10px;
min-width: 20px;
text-align: center;
}
.nav-04__tab.is-active .nav-04__tab-count {
background: #ffe8df;
color: var(--accent);
}
/* Mobile */
#nav-04-toggle {
display: none;
}
.nav-04__hamburger {
display: none;
flex-direction: column;
gap: 5px;
cursor: pointer;
padding: 8px;
border: none;
background: transparent;
}
.nav-04__hamburger span {
display: block;
width: 22px;
height: 2px;
background: var(--text);
border-radius: 2px;
transition: transform 0.3s, opacity 0.3s;
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(1) {
transform: translateY(7px) rotate(45deg);
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(2) {
opacity: 0;
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(3) {
transform: translateY(-7px) rotate(-45deg);
}
.nav-04__mobile {
display: none;
flex-direction: column;
gap: 0.25rem;
padding: 0.75rem 1.5rem 1rem;
border-top: 1px solid var(--track);
}
.nav-04__mobile a {
display: block;
padding: 0.6rem 0.5rem;
color: var(--text);
text-decoration: none;
font-weight: 600;
font-size: 0.95rem;
border-radius: 6px;
transition: background 0.15s, color 0.15s;
}
.nav-04__mobile a:hover {
background: #ffe8df;
color: var(--accent);
padding-left: 1rem;
}
#nav-04-toggle:checked ~ .nav-04__mobile {
display: flex;
}
@media (max-width: 640px) {
.nav-04__tabs,
.nav-04__actions {
display: none;
}
.nav-04__hamburger {
display: flex;
}
}
@media (prefers-reduced-motion: reduce) {
.nav-04__tab::after {
transition: none;
}
.nav-04__btn {
transition: none;
}
.nav-04__hamburger span {
transition: none;
}
}Here's a working CSS Responsive Navbar Design from CodeFronts. Use it as-is or adapt to your framework. All classes are scoped under a unique prefix so the code won't collide with your existing styles. MIT licensed.
Demo: CSS Animated Underline Tabs Navbar
Source: https://codefronts.com/navigation/css-responsive-navbar/css-animated-underline-tabs-navbar/
Tab-style navbar with an animated bottom border that slides between items using CSS transitions and radio-button state.
## HTML
```html
<div class="nav-04">
<input type="checkbox" id="nav-04-toggle">
<div class="nav-04__top">
<a href="#" class="nav-04__logo">Stack<span>.</span></a>
<div class="nav-04__spacer"></div>
<div class="nav-04__actions">
<a href="#" class="nav-04__action-link">Sign in</a>
<button class="nav-04__btn">Start building</button>
</div>
<label for="nav-04-toggle" class="nav-04__hamburger" aria-label="Toggle menu">
<span></span><span></span><span></span>
</label>
</div>
<div class="nav-04__tabs">
<a href="#" class="nav-04__tab is-active">Overview</a>
<a href="#" class="nav-04__tab">Components <span class="nav-04__tab-count">48</span></a>
<a href="#" class="nav-04__tab">Templates <span class="nav-04__tab-count">12</span></a>
<a href="#" class="nav-04__tab">Documentation</a>
<a href="#" class="nav-04__tab">Changelog <span class="nav-04__tab-count">3</span></a>
<a href="#" class="nav-04__tab">Community</a>
<a href="#" class="nav-04__tab">Showcase</a>
</div>
<div class="nav-04__mobile">
<a href="#">Overview</a>
<a href="#">Components</a>
<a href="#">Templates</a>
<a href="#">Documentation</a>
<a href="#">Changelog</a>
<a href="#">Community</a>
<a href="#">Showcase</a>
</div>
</div>
<div style="padding:4rem 2.5rem; max-width:700px; margin:0 auto;">
<h1 style="font-size:2.5rem; font-weight:800; letter-spacing:-0.04em; margin-bottom:1rem;">Animated Underline <span style="color:#ff6b35;">Tabs Navbar</span></h1>
<p style="color:#888; font-size:1.1rem; line-height:1.7;">The sliding underline is a <code>scaleX</code> transform on an <code>::after</code> pseudo-element. Hover shows a 60% preview; active tab shows 100% width. No JavaScript.</p>
</div>
```
## CSS
```css
.nav-04,
.nav-04 *,
.nav-04 *::before,
.nav-04 *::after {
margin: 0;
padding: 0;
box-sizing: border-box;
}
.nav-04 {
--bg: #fff;
--text: #1c1c1c;
--muted: #888;
--accent: #ff6b35;
--track: #f0ebe3;
font-family: 'Manrope', sans-serif;
background: var(--bg);
border-bottom: 1px solid #f0ebe3;
position: sticky;
top: 0;
z-index: 100;
}
.nav-04__top {
display: flex;
align-items: center;
padding: 0 2.5rem;
height: 60px;
gap: 2rem;
}
.nav-04__logo {
font-weight: 800;
font-size: 1.25rem;
color: var(--text);
text-decoration: none;
letter-spacing: -0.04em;
flex-shrink: 0;
}
.nav-04__logo span {
color: var(--accent);
}
.nav-04__spacer {
flex: 1;
}
.nav-04__actions {
display: flex;
align-items: center;
gap: 0.75rem;
}
.nav-04__action-link {
font-size: 0.875rem;
font-weight: 600;
color: var(--muted);
text-decoration: none;
transition: color 0.2s;
}
.nav-04__action-link:hover {
color: var(--text);
}
.nav-04__btn {
padding: 0.45rem 1.1rem;
border-radius: 6px;
font-size: 0.875rem;
font-weight: 700;
cursor: pointer;
border: none;
font-family: inherit;
background: var(--text);
color: #fff;
transition: background 0.2s, transform 0.15s;
letter-spacing: -0.01em;
}
.nav-04__btn:hover {
background: var(--accent);
transform: translateY(-1px);
}
/* Tab nav */
.nav-04__tabs {
display: flex;
align-items: flex-end;
padding: 0 2.5rem;
overflow-x: auto;
scrollbar-width: none;
gap: 0;
height: 48px;
}
.nav-04__tabs::-webkit-scrollbar {
display: none;
}
.nav-04__tab {
flex-shrink: 0;
position: relative;
display: inline-flex;
align-items: center;
gap: 6px;
padding: 0 1.25rem;
height: 100%;
font-size: 0.875rem;
font-weight: 600;
color: var(--muted);
text-decoration: none;
transition: color 0.2s;
white-space: nowrap;
}
.nav-04__tab::after {
content: '';
position: absolute;
bottom: 0;
left: 0;
right: 0;
height: 2.5px;
background: var(--accent);
border-radius: 2px 2px 0 0;
transform: scaleX(0);
transition: transform 0.25s cubic-bezier(.4,0,.2,1);
}
.nav-04__tab:hover {
color: var(--text);
}
.nav-04__tab:hover::after {
transform: scaleX(0.6);
}
.nav-04__tab.is-active {
color: var(--accent);
}
.nav-04__tab.is-active::after {
transform: scaleX(1);
}
.nav-04__tab-count {
font-size: 0.7rem;
font-weight: 700;
background: var(--track);
color: var(--muted);
padding: 1px 6px;
border-radius: 10px;
min-width: 20px;
text-align: center;
}
.nav-04__tab.is-active .nav-04__tab-count {
background: #ffe8df;
color: var(--accent);
}
/* Mobile */
#nav-04-toggle {
display: none;
}
.nav-04__hamburger {
display: none;
flex-direction: column;
gap: 5px;
cursor: pointer;
padding: 8px;
border: none;
background: transparent;
}
.nav-04__hamburger span {
display: block;
width: 22px;
height: 2px;
background: var(--text);
border-radius: 2px;
transition: transform 0.3s, opacity 0.3s;
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(1) {
transform: translateY(7px) rotate(45deg);
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(2) {
opacity: 0;
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(3) {
transform: translateY(-7px) rotate(-45deg);
}
.nav-04__mobile {
display: none;
flex-direction: column;
gap: 0.25rem;
padding: 0.75rem 1.5rem 1rem;
border-top: 1px solid var(--track);
}
.nav-04__mobile a {
display: block;
padding: 0.6rem 0.5rem;
color: var(--text);
text-decoration: none;
font-weight: 600;
font-size: 0.95rem;
border-radius: 6px;
transition: background 0.15s, color 0.15s;
}
.nav-04__mobile a:hover {
background: #ffe8df;
color: var(--accent);
padding-left: 1rem;
}
#nav-04-toggle:checked ~ .nav-04__mobile {
display: flex;
}
@media (max-width: 640px) {
.nav-04__tabs,
.nav-04__actions {
display: none;
}
.nav-04__hamburger {
display: flex;
}
}
@media (prefers-reduced-motion: reduce) {
.nav-04__tab::after {
transition: none;
}
.nav-04__btn {
transition: none;
}
.nav-04__hamburger span {
transition: none;
}
}
```Paste this into ChatGPT, Claude, Cursor, or any coding assistant. The block below is pre-framed with everything the AI needs to integrate this demo into your project — markup, styles, scoping notes, and the source URL. Hit Copy and paste straight into your chat.
Here's a working CSS Responsive Navbar Design from CodeFronts. Use it as-is or adapt to your framework. All classes are scoped under a unique prefix so the code won't collide with your existing styles. MIT licensed.
Demo: CSS Animated Underline Tabs Navbar
Source: https://codefronts.com/navigation/css-responsive-navbar/css-animated-underline-tabs-navbar/
Tab-style navbar with an animated bottom border that slides between items using CSS transitions and radio-button state.
## HTML
```html
<div class="nav-04">
<input type="checkbox" id="nav-04-toggle">
<div class="nav-04__top">
<a href="#" class="nav-04__logo">Stack<span>.</span></a>
<div class="nav-04__spacer"></div>
<div class="nav-04__actions">
<a href="#" class="nav-04__action-link">Sign in</a>
<button class="nav-04__btn">Start building</button>
</div>
<label for="nav-04-toggle" class="nav-04__hamburger" aria-label="Toggle menu">
<span></span><span></span><span></span>
</label>
</div>
<div class="nav-04__tabs">
<a href="#" class="nav-04__tab is-active">Overview</a>
<a href="#" class="nav-04__tab">Components <span class="nav-04__tab-count">48</span></a>
<a href="#" class="nav-04__tab">Templates <span class="nav-04__tab-count">12</span></a>
<a href="#" class="nav-04__tab">Documentation</a>
<a href="#" class="nav-04__tab">Changelog <span class="nav-04__tab-count">3</span></a>
<a href="#" class="nav-04__tab">Community</a>
<a href="#" class="nav-04__tab">Showcase</a>
</div>
<div class="nav-04__mobile">
<a href="#">Overview</a>
<a href="#">Components</a>
<a href="#">Templates</a>
<a href="#">Documentation</a>
<a href="#">Changelog</a>
<a href="#">Community</a>
<a href="#">Showcase</a>
</div>
</div>
<div style="padding:4rem 2.5rem; max-width:700px; margin:0 auto;">
<h1 style="font-size:2.5rem; font-weight:800; letter-spacing:-0.04em; margin-bottom:1rem;">Animated Underline <span style="color:#ff6b35;">Tabs Navbar</span></h1>
<p style="color:#888; font-size:1.1rem; line-height:1.7;">The sliding underline is a <code>scaleX</code> transform on an <code>::after</code> pseudo-element. Hover shows a 60% preview; active tab shows 100% width. No JavaScript.</p>
</div>
```
## CSS
```css
.nav-04,
.nav-04 *,
.nav-04 *::before,
.nav-04 *::after {
margin: 0;
padding: 0;
box-sizing: border-box;
}
.nav-04 {
--bg: #fff;
--text: #1c1c1c;
--muted: #888;
--accent: #ff6b35;
--track: #f0ebe3;
font-family: 'Manrope', sans-serif;
background: var(--bg);
border-bottom: 1px solid #f0ebe3;
position: sticky;
top: 0;
z-index: 100;
}
.nav-04__top {
display: flex;
align-items: center;
padding: 0 2.5rem;
height: 60px;
gap: 2rem;
}
.nav-04__logo {
font-weight: 800;
font-size: 1.25rem;
color: var(--text);
text-decoration: none;
letter-spacing: -0.04em;
flex-shrink: 0;
}
.nav-04__logo span {
color: var(--accent);
}
.nav-04__spacer {
flex: 1;
}
.nav-04__actions {
display: flex;
align-items: center;
gap: 0.75rem;
}
.nav-04__action-link {
font-size: 0.875rem;
font-weight: 600;
color: var(--muted);
text-decoration: none;
transition: color 0.2s;
}
.nav-04__action-link:hover {
color: var(--text);
}
.nav-04__btn {
padding: 0.45rem 1.1rem;
border-radius: 6px;
font-size: 0.875rem;
font-weight: 700;
cursor: pointer;
border: none;
font-family: inherit;
background: var(--text);
color: #fff;
transition: background 0.2s, transform 0.15s;
letter-spacing: -0.01em;
}
.nav-04__btn:hover {
background: var(--accent);
transform: translateY(-1px);
}
/* Tab nav */
.nav-04__tabs {
display: flex;
align-items: flex-end;
padding: 0 2.5rem;
overflow-x: auto;
scrollbar-width: none;
gap: 0;
height: 48px;
}
.nav-04__tabs::-webkit-scrollbar {
display: none;
}
.nav-04__tab {
flex-shrink: 0;
position: relative;
display: inline-flex;
align-items: center;
gap: 6px;
padding: 0 1.25rem;
height: 100%;
font-size: 0.875rem;
font-weight: 600;
color: var(--muted);
text-decoration: none;
transition: color 0.2s;
white-space: nowrap;
}
.nav-04__tab::after {
content: '';
position: absolute;
bottom: 0;
left: 0;
right: 0;
height: 2.5px;
background: var(--accent);
border-radius: 2px 2px 0 0;
transform: scaleX(0);
transition: transform 0.25s cubic-bezier(.4,0,.2,1);
}
.nav-04__tab:hover {
color: var(--text);
}
.nav-04__tab:hover::after {
transform: scaleX(0.6);
}
.nav-04__tab.is-active {
color: var(--accent);
}
.nav-04__tab.is-active::after {
transform: scaleX(1);
}
.nav-04__tab-count {
font-size: 0.7rem;
font-weight: 700;
background: var(--track);
color: var(--muted);
padding: 1px 6px;
border-radius: 10px;
min-width: 20px;
text-align: center;
}
.nav-04__tab.is-active .nav-04__tab-count {
background: #ffe8df;
color: var(--accent);
}
/* Mobile */
#nav-04-toggle {
display: none;
}
.nav-04__hamburger {
display: none;
flex-direction: column;
gap: 5px;
cursor: pointer;
padding: 8px;
border: none;
background: transparent;
}
.nav-04__hamburger span {
display: block;
width: 22px;
height: 2px;
background: var(--text);
border-radius: 2px;
transition: transform 0.3s, opacity 0.3s;
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(1) {
transform: translateY(7px) rotate(45deg);
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(2) {
opacity: 0;
}
#nav-04-toggle:checked ~ .nav-04__top .nav-04__hamburger span:nth-child(3) {
transform: translateY(-7px) rotate(-45deg);
}
.nav-04__mobile {
display: none;
flex-direction: column;
gap: 0.25rem;
padding: 0.75rem 1.5rem 1rem;
border-top: 1px solid var(--track);
}
.nav-04__mobile a {
display: block;
padding: 0.6rem 0.5rem;
color: var(--text);
text-decoration: none;
font-weight: 600;
font-size: 0.95rem;
border-radius: 6px;
transition: background 0.15s, color 0.15s;
}
.nav-04__mobile a:hover {
background: #ffe8df;
color: var(--accent);
padding-left: 1rem;
}
#nav-04-toggle:checked ~ .nav-04__mobile {
display: flex;
}
@media (max-width: 640px) {
.nav-04__tabs,
.nav-04__actions {
display: none;
}
.nav-04__hamburger {
display: flex;
}
}
@media (prefers-reduced-motion: reduce) {
.nav-04__tab::after {
transition: none;
}
.nav-04__btn {
transition: none;
}
.nav-04__hamburger span {
transition: none;
}
}
```How this works
Each tab link has a ::after pseudo-element that serves as the underline. By default it is width: 0; opacity: 0. When the link carries the .is-active class or receives :hover, a CSS transition grows the width to 100% and fades it in. The active class is toggled by radio inputs hidden off-screen — checking one radio uses the ~ selector to apply .is-active styling to the corresponding label.
Make it yours
- Change underline thickness with
height: 3pxon the::afterelement — bump to4pxfor bolder emphasis. - Switch the animation from a width-grow to a scale transform:
transform: scaleX(0)→scaleX(1)withtransform-origin: leftfor a slide-in feel. - Move the indicator to the top by repositioning
bottom: -1pxtotop: -1px.
Gotchas — read before shipping
- Radio-based tab state doesn't persist across page loads — use URL hash links with
:targetif you need the active tab to survive a refresh. - The underline
::afterneedsposition: absoluteon the parent link set toposition: relative, otherwise it won't track the link width.
Browser support
| Chrome | Safari | Firefox | Edge |
|---|---|---|---|
| 49+ | 9+ | 44+ | 49+ |
All features are baseline CSS — no compatibility concerns for modern browsers.