17 CSS Side Menu Designs16 / 17
CSS-Only Accordion Side Navigation
A documentation-style sidebar where multiple independent accordion sections can be expanded or collapsed simultaneously using hidden checkboxes and max-height transitions.
Published
The code
<div class="sm-16">
<nav class="sm-16__nav">
<div class="sm-16__brand">
<div class="sm-16__logo">D</div>
<div>
<span class="sm-16__brand-name">DocBase</span>
<span class="sm-16__brand-version">v3.2</span>
</div>
</div>
<div class="sm-16__search">
<input type="text" class="sm-16__search-input" placeholder="Search docs…">
</div>
<a class="sm-16__flat" href="#"><span class="sm-16__flat-icon">⬡</span> Overview</a>
<!-- Accordion 1 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a1" checked>
<label class="sm-16__section-header" for="sm-16-a1">
<span><span class="sm-16__section-header-icon">◈</span> Getting Started</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item sm-16__item--active" href="#">Installation</a>
<a class="sm-16__item" href="#">Configuration</a>
<a class="sm-16__item" href="#">Quick Start</a>
<a class="sm-16__item" href="#">Examples</a>
</div>
</div>
<!-- Accordion 2 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a2">
<label class="sm-16__section-header" for="sm-16-a2">
<span><span class="sm-16__section-header-icon">▦</span> Core Concepts</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Architecture</a>
<a class="sm-16__item" href="#">Data Flow</a>
<a class="sm-16__item" href="#">State Management</a>
<a class="sm-16__item" href="#">Routing</a>
</div>
</div>
<!-- Accordion 3 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a3">
<label class="sm-16__section-header" for="sm-16-a3">
<span><span class="sm-16__section-header-icon">◉</span> API Reference</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Endpoints <span class="sm-16__item-badge">48</span></a>
<a class="sm-16__item" href="#">Authentication</a>
<a class="sm-16__item" href="#">Webhooks</a>
<a class="sm-16__item" href="#">Rate Limits</a>
</div>
</div>
<!-- Accordion 4 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a4">
<label class="sm-16__section-header" for="sm-16-a4">
<span><span class="sm-16__section-header-icon">◬</span> Guides</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Deployment</a>
<a class="sm-16__item" href="#">Performance</a>
<a class="sm-16__item" href="#">Security</a>
</div>
</div>
<a class="sm-16__flat" href="#"><span class="sm-16__flat-icon">⬙</span> Changelog</a>
</nav>
<div class="sm-16__main">
<div class="sm-16__heading">Documentation</div>
<div class="sm-16__sub">CSS-only accordion sidebar: each section uses a hidden <code>checkbox</code> and <code>max-height</code> transition. Clicking a header expands/collapses its items independently.</div>
<div class="sm-16__docs">
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">📦</div>
<div>
<div class="sm-16__doc-title">Installation Guide</div>
<div class="sm-16__doc-sub">Set up your environment in under 5 minutes</div>
</div>
</div>
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">⚙️</div>
<div>
<div class="sm-16__doc-title">Configuration Reference</div>
<div class="sm-16__doc-sub">All available options with examples</div>
</div>
</div>
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">🚀</div>
<div>
<div class="sm-16__doc-title">Quick Start Tutorial</div>
<div class="sm-16__doc-sub">Build your first integration in 10 steps</div>
</div>
</div>
</div>
</div>
</div><div class="sm-16">
<nav class="sm-16__nav">
<div class="sm-16__brand">
<div class="sm-16__logo">D</div>
<div>
<span class="sm-16__brand-name">DocBase</span>
<span class="sm-16__brand-version">v3.2</span>
</div>
</div>
<div class="sm-16__search">
<input type="text" class="sm-16__search-input" placeholder="Search docs…">
</div>
<a class="sm-16__flat" href="#"><span class="sm-16__flat-icon">⬡</span> Overview</a>
<!-- Accordion 1 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a1" checked>
<label class="sm-16__section-header" for="sm-16-a1">
<span><span class="sm-16__section-header-icon">◈</span> Getting Started</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item sm-16__item--active" href="#">Installation</a>
<a class="sm-16__item" href="#">Configuration</a>
<a class="sm-16__item" href="#">Quick Start</a>
<a class="sm-16__item" href="#">Examples</a>
</div>
</div>
<!-- Accordion 2 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a2">
<label class="sm-16__section-header" for="sm-16-a2">
<span><span class="sm-16__section-header-icon">▦</span> Core Concepts</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Architecture</a>
<a class="sm-16__item" href="#">Data Flow</a>
<a class="sm-16__item" href="#">State Management</a>
<a class="sm-16__item" href="#">Routing</a>
</div>
</div>
<!-- Accordion 3 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a3">
<label class="sm-16__section-header" for="sm-16-a3">
<span><span class="sm-16__section-header-icon">◉</span> API Reference</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Endpoints <span class="sm-16__item-badge">48</span></a>
<a class="sm-16__item" href="#">Authentication</a>
<a class="sm-16__item" href="#">Webhooks</a>
<a class="sm-16__item" href="#">Rate Limits</a>
</div>
</div>
<!-- Accordion 4 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a4">
<label class="sm-16__section-header" for="sm-16-a4">
<span><span class="sm-16__section-header-icon">◬</span> Guides</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Deployment</a>
<a class="sm-16__item" href="#">Performance</a>
<a class="sm-16__item" href="#">Security</a>
</div>
</div>
<a class="sm-16__flat" href="#"><span class="sm-16__flat-icon">⬙</span> Changelog</a>
</nav>
<div class="sm-16__main">
<div class="sm-16__heading">Documentation</div>
<div class="sm-16__sub">CSS-only accordion sidebar: each section uses a hidden <code>checkbox</code> and <code>max-height</code> transition. Clicking a header expands/collapses its items independently.</div>
<div class="sm-16__docs">
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">📦</div>
<div>
<div class="sm-16__doc-title">Installation Guide</div>
<div class="sm-16__doc-sub">Set up your environment in under 5 minutes</div>
</div>
</div>
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">⚙️</div>
<div>
<div class="sm-16__doc-title">Configuration Reference</div>
<div class="sm-16__doc-sub">All available options with examples</div>
</div>
</div>
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">🚀</div>
<div>
<div class="sm-16__doc-title">Quick Start Tutorial</div>
<div class="sm-16__doc-sub">Build your first integration in 10 steps</div>
</div>
</div>
</div>
</div>
</div>.sm-16,
.sm-16 *,
.sm-16 *::before,
.sm-16 *::after {
box-sizing: border-box;
margin: 0;
padding: 0;
}
.sm-16 ::selection {
background: #2563eb;
color: #fff;
}
.sm-16 {
--bg: #f0f4ff;
--surface: #fff;
--nav-bg: #fff;
--accent: #2563eb;
--accent2: #60a5fa;
--text: #0f172a;
--muted: #94a3b8;
--muted2: #64748b;
--border: #e2e8f0;
--border-active: rgba(37,99,235,0.15);
--font: 'Plus Jakarta Sans', system-ui, sans-serif;
font-family: var(--font);
background: var(--bg);
color: var(--text);
display: flex;
min-height: 100vh;
border-radius: 12px;
overflow: hidden;
}
/* Accordion hidden radio/checkboxes */
.sm-16__acc-toggle {
display: none;
}
/* Sidebar */
.sm-16__nav {
width: 240px;
background: var(--nav-bg);
border-right: 1px solid var(--border);
display: flex;
flex-direction: column;
flex-shrink: 0;
overflow-y: auto;
}
.sm-16__nav::-webkit-scrollbar {
width: 3px;
}
.sm-16__nav::-webkit-scrollbar-thumb {
background: var(--border);
border-radius: 3px;
}
.sm-16__brand {
padding: 18px 16px;
border-bottom: 1px solid var(--border);
display: flex;
align-items: center;
gap: 10px;
flex-shrink: 0;
}
.sm-16__logo {
width: 32px;
height: 32px;
background: var(--accent);
border-radius: 8px;
display: flex;
align-items: center;
justify-content: center;
font-weight: 800;
color: #fff;
font-size: 14px;
}
.sm-16__brand-name {
font-size: 14px;
font-weight: 800;
}
.sm-16__brand-version {
font-size: 10px;
color: var(--muted);
margin-left: 4px;
font-weight: 500;
}
/* Search bar */
.sm-16__search {
padding: 10px 14px;
border-bottom: 1px solid var(--border);
flex-shrink: 0;
}
.sm-16__search-input {
width: 100%;
padding: 7px 12px;
background: var(--bg);
border: 1px solid var(--border);
border-radius: 7px;
font-size: 12px;
font-family: var(--font);
color: var(--text);
outline: none;
}
.sm-16__search-input:focus {
border-color: var(--accent2);
}
/* Accordion section */
.sm-16__section {
border-bottom: 1px solid var(--border);
}
/* Section header — label acts as click target */
.sm-16__section-header {
display: flex;
align-items: center;
justify-content: space-between;
padding: 12px 16px;
cursor: pointer;
user-select: none;
transition: background 0.15s;
font-size: 12px;
font-weight: 700;
text-transform: uppercase;
letter-spacing: 0.1em;
color: var(--muted2);
}
.sm-16__section-header:hover {
background: rgba(37,99,235,0.04);
}
.sm-16__section-header-icon {
font-size: 14px;
}
/* Chevron */
.sm-16__chevron {
font-size: 12px;
color: var(--muted);
transition: transform 0.3s cubic-bezier(0.4,0,0.2,1);
display: inline-block;
}
.sm-16__acc-toggle:checked + .sm-16__section-header .sm-16__chevron {
transform: rotate(90deg);
}
.sm-16__acc-toggle:checked + .sm-16__section-header {
color: var(--accent);
}
/* Collapsible sub-items */
.sm-16__items {
max-height: 0;
overflow: hidden;
transition: max-height 0.38s cubic-bezier(0.4,0,0.2,1);
}
.sm-16__acc-toggle:checked + .sm-16__section-header + .sm-16__items {
max-height: 400px;
}
/* Individual link items */
.sm-16__item {
display: flex;
align-items: center;
gap: 10px;
padding: 9px 16px 9px 36px;
color: var(--muted2);
font-size: 13px;
font-weight: 600;
cursor: pointer;
text-decoration: none;
transition: all 0.15s;
position: relative;
}
.sm-16__item::before {
content: '';
position: absolute;
left: 20px;
top: 50%;
transform: translateY(-50%);
width: 4px;
height: 4px;
border-radius: 50%;
background: var(--muted);
transition: background 0.15s, transform 0.15s;
}
.sm-16__item:hover {
color: var(--accent);
background: rgba(37,99,235,0.05);
}
.sm-16__item:hover::before {
background: var(--accent);
transform: translateY(-50%) scale(1.4);
}
.sm-16__item--active {
color: var(--accent);
background: rgba(37,99,235,0.07);
}
.sm-16__item--active::before {
background: var(--accent);
}
.sm-16__item-badge {
margin-left: auto;
background: rgba(37,99,235,0.12);
color: var(--accent);
font-size: 10px;
font-weight: 700;
padding: 1px 6px;
border-radius: 99px;
}
/* Flat link */
.sm-16__flat {
display: flex;
align-items: center;
gap: 10px;
padding: 11px 16px;
color: var(--muted2);
font-size: 13px;
font-weight: 600;
cursor: pointer;
text-decoration: none;
transition: all 0.15s;
border-bottom: 1px solid var(--border);
}
.sm-16__flat:hover {
color: var(--accent);
background: rgba(37,99,235,0.04);
}
.sm-16__flat-icon {
font-size: 14px;
}
/* Main */
.sm-16__main {
flex: 1;
padding: 24px;
}
.sm-16__heading {
font-size: 20px;
font-weight: 800;
margin-bottom: 6px;
}
.sm-16__sub {
font-size: 13px;
color: var(--muted2);
line-height: 1.7;
margin-bottom: 22px;
}
.sm-16__docs {
display: flex;
flex-direction: column;
gap: 10px;
}
.sm-16__doc-card {
background: var(--surface);
border: 1px solid var(--border);
border-radius: 10px;
padding: 14px 16px;
display: flex;
align-items: center;
gap: 12px;
cursor: pointer;
transition: border-color 0.2s, box-shadow 0.2s;
}
.sm-16__doc-card:hover {
border-color: var(--accent2);
box-shadow: 0 2px 12px rgba(37,99,235,0.08);
}
.sm-16__doc-icon {
width: 34px;
height: 34px;
border-radius: 8px;
background: rgba(37,99,235,0.08);
display: flex;
align-items: center;
justify-content: center;
font-size: 16px;
flex-shrink: 0;
}
.sm-16__doc-title {
font-size: 13px;
font-weight: 700;
margin-bottom: 2px;
}
.sm-16__doc-sub {
font-size: 12px;
color: var(--muted);
}
@media (prefers-reduced-motion: reduce) {
.sm-16__items,
.sm-16__chevron {
transition: none;
}
}.sm-16,
.sm-16 *,
.sm-16 *::before,
.sm-16 *::after {
box-sizing: border-box;
margin: 0;
padding: 0;
}
.sm-16 ::selection {
background: #2563eb;
color: #fff;
}
.sm-16 {
--bg: #f0f4ff;
--surface: #fff;
--nav-bg: #fff;
--accent: #2563eb;
--accent2: #60a5fa;
--text: #0f172a;
--muted: #94a3b8;
--muted2: #64748b;
--border: #e2e8f0;
--border-active: rgba(37,99,235,0.15);
--font: 'Plus Jakarta Sans', system-ui, sans-serif;
font-family: var(--font);
background: var(--bg);
color: var(--text);
display: flex;
min-height: 100vh;
border-radius: 12px;
overflow: hidden;
}
/* Accordion hidden radio/checkboxes */
.sm-16__acc-toggle {
display: none;
}
/* Sidebar */
.sm-16__nav {
width: 240px;
background: var(--nav-bg);
border-right: 1px solid var(--border);
display: flex;
flex-direction: column;
flex-shrink: 0;
overflow-y: auto;
}
.sm-16__nav::-webkit-scrollbar {
width: 3px;
}
.sm-16__nav::-webkit-scrollbar-thumb {
background: var(--border);
border-radius: 3px;
}
.sm-16__brand {
padding: 18px 16px;
border-bottom: 1px solid var(--border);
display: flex;
align-items: center;
gap: 10px;
flex-shrink: 0;
}
.sm-16__logo {
width: 32px;
height: 32px;
background: var(--accent);
border-radius: 8px;
display: flex;
align-items: center;
justify-content: center;
font-weight: 800;
color: #fff;
font-size: 14px;
}
.sm-16__brand-name {
font-size: 14px;
font-weight: 800;
}
.sm-16__brand-version {
font-size: 10px;
color: var(--muted);
margin-left: 4px;
font-weight: 500;
}
/* Search bar */
.sm-16__search {
padding: 10px 14px;
border-bottom: 1px solid var(--border);
flex-shrink: 0;
}
.sm-16__search-input {
width: 100%;
padding: 7px 12px;
background: var(--bg);
border: 1px solid var(--border);
border-radius: 7px;
font-size: 12px;
font-family: var(--font);
color: var(--text);
outline: none;
}
.sm-16__search-input:focus {
border-color: var(--accent2);
}
/* Accordion section */
.sm-16__section {
border-bottom: 1px solid var(--border);
}
/* Section header — label acts as click target */
.sm-16__section-header {
display: flex;
align-items: center;
justify-content: space-between;
padding: 12px 16px;
cursor: pointer;
user-select: none;
transition: background 0.15s;
font-size: 12px;
font-weight: 700;
text-transform: uppercase;
letter-spacing: 0.1em;
color: var(--muted2);
}
.sm-16__section-header:hover {
background: rgba(37,99,235,0.04);
}
.sm-16__section-header-icon {
font-size: 14px;
}
/* Chevron */
.sm-16__chevron {
font-size: 12px;
color: var(--muted);
transition: transform 0.3s cubic-bezier(0.4,0,0.2,1);
display: inline-block;
}
.sm-16__acc-toggle:checked + .sm-16__section-header .sm-16__chevron {
transform: rotate(90deg);
}
.sm-16__acc-toggle:checked + .sm-16__section-header {
color: var(--accent);
}
/* Collapsible sub-items */
.sm-16__items {
max-height: 0;
overflow: hidden;
transition: max-height 0.38s cubic-bezier(0.4,0,0.2,1);
}
.sm-16__acc-toggle:checked + .sm-16__section-header + .sm-16__items {
max-height: 400px;
}
/* Individual link items */
.sm-16__item {
display: flex;
align-items: center;
gap: 10px;
padding: 9px 16px 9px 36px;
color: var(--muted2);
font-size: 13px;
font-weight: 600;
cursor: pointer;
text-decoration: none;
transition: all 0.15s;
position: relative;
}
.sm-16__item::before {
content: '';
position: absolute;
left: 20px;
top: 50%;
transform: translateY(-50%);
width: 4px;
height: 4px;
border-radius: 50%;
background: var(--muted);
transition: background 0.15s, transform 0.15s;
}
.sm-16__item:hover {
color: var(--accent);
background: rgba(37,99,235,0.05);
}
.sm-16__item:hover::before {
background: var(--accent);
transform: translateY(-50%) scale(1.4);
}
.sm-16__item--active {
color: var(--accent);
background: rgba(37,99,235,0.07);
}
.sm-16__item--active::before {
background: var(--accent);
}
.sm-16__item-badge {
margin-left: auto;
background: rgba(37,99,235,0.12);
color: var(--accent);
font-size: 10px;
font-weight: 700;
padding: 1px 6px;
border-radius: 99px;
}
/* Flat link */
.sm-16__flat {
display: flex;
align-items: center;
gap: 10px;
padding: 11px 16px;
color: var(--muted2);
font-size: 13px;
font-weight: 600;
cursor: pointer;
text-decoration: none;
transition: all 0.15s;
border-bottom: 1px solid var(--border);
}
.sm-16__flat:hover {
color: var(--accent);
background: rgba(37,99,235,0.04);
}
.sm-16__flat-icon {
font-size: 14px;
}
/* Main */
.sm-16__main {
flex: 1;
padding: 24px;
}
.sm-16__heading {
font-size: 20px;
font-weight: 800;
margin-bottom: 6px;
}
.sm-16__sub {
font-size: 13px;
color: var(--muted2);
line-height: 1.7;
margin-bottom: 22px;
}
.sm-16__docs {
display: flex;
flex-direction: column;
gap: 10px;
}
.sm-16__doc-card {
background: var(--surface);
border: 1px solid var(--border);
border-radius: 10px;
padding: 14px 16px;
display: flex;
align-items: center;
gap: 12px;
cursor: pointer;
transition: border-color 0.2s, box-shadow 0.2s;
}
.sm-16__doc-card:hover {
border-color: var(--accent2);
box-shadow: 0 2px 12px rgba(37,99,235,0.08);
}
.sm-16__doc-icon {
width: 34px;
height: 34px;
border-radius: 8px;
background: rgba(37,99,235,0.08);
display: flex;
align-items: center;
justify-content: center;
font-size: 16px;
flex-shrink: 0;
}
.sm-16__doc-title {
font-size: 13px;
font-weight: 700;
margin-bottom: 2px;
}
.sm-16__doc-sub {
font-size: 12px;
color: var(--muted);
}
@media (prefers-reduced-motion: reduce) {
.sm-16__items,
.sm-16__chevron {
transition: none;
}
}Here's a working CSS Side Menu 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-Only Accordion Side Navigation
Source: https://codefronts.com/navigation/css-side-menu/css-only-accordion-side-navigation/
A documentation-style sidebar where multiple independent accordion sections can be expanded or collapsed simultaneously using hidden checkboxes and max-height transitions.
## HTML
```html
<div class="sm-16">
<nav class="sm-16__nav">
<div class="sm-16__brand">
<div class="sm-16__logo">D</div>
<div>
<span class="sm-16__brand-name">DocBase</span>
<span class="sm-16__brand-version">v3.2</span>
</div>
</div>
<div class="sm-16__search">
<input type="text" class="sm-16__search-input" placeholder="Search docs…">
</div>
<a class="sm-16__flat" href="#"><span class="sm-16__flat-icon">⬡</span> Overview</a>
<!-- Accordion 1 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a1" checked>
<label class="sm-16__section-header" for="sm-16-a1">
<span><span class="sm-16__section-header-icon">◈</span> Getting Started</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item sm-16__item--active" href="#">Installation</a>
<a class="sm-16__item" href="#">Configuration</a>
<a class="sm-16__item" href="#">Quick Start</a>
<a class="sm-16__item" href="#">Examples</a>
</div>
</div>
<!-- Accordion 2 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a2">
<label class="sm-16__section-header" for="sm-16-a2">
<span><span class="sm-16__section-header-icon">▦</span> Core Concepts</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Architecture</a>
<a class="sm-16__item" href="#">Data Flow</a>
<a class="sm-16__item" href="#">State Management</a>
<a class="sm-16__item" href="#">Routing</a>
</div>
</div>
<!-- Accordion 3 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a3">
<label class="sm-16__section-header" for="sm-16-a3">
<span><span class="sm-16__section-header-icon">◉</span> API Reference</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Endpoints <span class="sm-16__item-badge">48</span></a>
<a class="sm-16__item" href="#">Authentication</a>
<a class="sm-16__item" href="#">Webhooks</a>
<a class="sm-16__item" href="#">Rate Limits</a>
</div>
</div>
<!-- Accordion 4 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a4">
<label class="sm-16__section-header" for="sm-16-a4">
<span><span class="sm-16__section-header-icon">◬</span> Guides</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Deployment</a>
<a class="sm-16__item" href="#">Performance</a>
<a class="sm-16__item" href="#">Security</a>
</div>
</div>
<a class="sm-16__flat" href="#"><span class="sm-16__flat-icon">⬙</span> Changelog</a>
</nav>
<div class="sm-16__main">
<div class="sm-16__heading">Documentation</div>
<div class="sm-16__sub">CSS-only accordion sidebar: each section uses a hidden <code>checkbox</code> and <code>max-height</code> transition. Clicking a header expands/collapses its items independently.</div>
<div class="sm-16__docs">
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">📦</div>
<div>
<div class="sm-16__doc-title">Installation Guide</div>
<div class="sm-16__doc-sub">Set up your environment in under 5 minutes</div>
</div>
</div>
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">⚙️</div>
<div>
<div class="sm-16__doc-title">Configuration Reference</div>
<div class="sm-16__doc-sub">All available options with examples</div>
</div>
</div>
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">🚀</div>
<div>
<div class="sm-16__doc-title">Quick Start Tutorial</div>
<div class="sm-16__doc-sub">Build your first integration in 10 steps</div>
</div>
</div>
</div>
</div>
</div>
```
## CSS
```css
.sm-16,
.sm-16 *,
.sm-16 *::before,
.sm-16 *::after {
box-sizing: border-box;
margin: 0;
padding: 0;
}
.sm-16 ::selection {
background: #2563eb;
color: #fff;
}
.sm-16 {
--bg: #f0f4ff;
--surface: #fff;
--nav-bg: #fff;
--accent: #2563eb;
--accent2: #60a5fa;
--text: #0f172a;
--muted: #94a3b8;
--muted2: #64748b;
--border: #e2e8f0;
--border-active: rgba(37,99,235,0.15);
--font: 'Plus Jakarta Sans', system-ui, sans-serif;
font-family: var(--font);
background: var(--bg);
color: var(--text);
display: flex;
min-height: 100vh;
border-radius: 12px;
overflow: hidden;
}
/* Accordion hidden radio/checkboxes */
.sm-16__acc-toggle {
display: none;
}
/* Sidebar */
.sm-16__nav {
width: 240px;
background: var(--nav-bg);
border-right: 1px solid var(--border);
display: flex;
flex-direction: column;
flex-shrink: 0;
overflow-y: auto;
}
.sm-16__nav::-webkit-scrollbar {
width: 3px;
}
.sm-16__nav::-webkit-scrollbar-thumb {
background: var(--border);
border-radius: 3px;
}
.sm-16__brand {
padding: 18px 16px;
border-bottom: 1px solid var(--border);
display: flex;
align-items: center;
gap: 10px;
flex-shrink: 0;
}
.sm-16__logo {
width: 32px;
height: 32px;
background: var(--accent);
border-radius: 8px;
display: flex;
align-items: center;
justify-content: center;
font-weight: 800;
color: #fff;
font-size: 14px;
}
.sm-16__brand-name {
font-size: 14px;
font-weight: 800;
}
.sm-16__brand-version {
font-size: 10px;
color: var(--muted);
margin-left: 4px;
font-weight: 500;
}
/* Search bar */
.sm-16__search {
padding: 10px 14px;
border-bottom: 1px solid var(--border);
flex-shrink: 0;
}
.sm-16__search-input {
width: 100%;
padding: 7px 12px;
background: var(--bg);
border: 1px solid var(--border);
border-radius: 7px;
font-size: 12px;
font-family: var(--font);
color: var(--text);
outline: none;
}
.sm-16__search-input:focus {
border-color: var(--accent2);
}
/* Accordion section */
.sm-16__section {
border-bottom: 1px solid var(--border);
}
/* Section header — label acts as click target */
.sm-16__section-header {
display: flex;
align-items: center;
justify-content: space-between;
padding: 12px 16px;
cursor: pointer;
user-select: none;
transition: background 0.15s;
font-size: 12px;
font-weight: 700;
text-transform: uppercase;
letter-spacing: 0.1em;
color: var(--muted2);
}
.sm-16__section-header:hover {
background: rgba(37,99,235,0.04);
}
.sm-16__section-header-icon {
font-size: 14px;
}
/* Chevron */
.sm-16__chevron {
font-size: 12px;
color: var(--muted);
transition: transform 0.3s cubic-bezier(0.4,0,0.2,1);
display: inline-block;
}
.sm-16__acc-toggle:checked + .sm-16__section-header .sm-16__chevron {
transform: rotate(90deg);
}
.sm-16__acc-toggle:checked + .sm-16__section-header {
color: var(--accent);
}
/* Collapsible sub-items */
.sm-16__items {
max-height: 0;
overflow: hidden;
transition: max-height 0.38s cubic-bezier(0.4,0,0.2,1);
}
.sm-16__acc-toggle:checked + .sm-16__section-header + .sm-16__items {
max-height: 400px;
}
/* Individual link items */
.sm-16__item {
display: flex;
align-items: center;
gap: 10px;
padding: 9px 16px 9px 36px;
color: var(--muted2);
font-size: 13px;
font-weight: 600;
cursor: pointer;
text-decoration: none;
transition: all 0.15s;
position: relative;
}
.sm-16__item::before {
content: '';
position: absolute;
left: 20px;
top: 50%;
transform: translateY(-50%);
width: 4px;
height: 4px;
border-radius: 50%;
background: var(--muted);
transition: background 0.15s, transform 0.15s;
}
.sm-16__item:hover {
color: var(--accent);
background: rgba(37,99,235,0.05);
}
.sm-16__item:hover::before {
background: var(--accent);
transform: translateY(-50%) scale(1.4);
}
.sm-16__item--active {
color: var(--accent);
background: rgba(37,99,235,0.07);
}
.sm-16__item--active::before {
background: var(--accent);
}
.sm-16__item-badge {
margin-left: auto;
background: rgba(37,99,235,0.12);
color: var(--accent);
font-size: 10px;
font-weight: 700;
padding: 1px 6px;
border-radius: 99px;
}
/* Flat link */
.sm-16__flat {
display: flex;
align-items: center;
gap: 10px;
padding: 11px 16px;
color: var(--muted2);
font-size: 13px;
font-weight: 600;
cursor: pointer;
text-decoration: none;
transition: all 0.15s;
border-bottom: 1px solid var(--border);
}
.sm-16__flat:hover {
color: var(--accent);
background: rgba(37,99,235,0.04);
}
.sm-16__flat-icon {
font-size: 14px;
}
/* Main */
.sm-16__main {
flex: 1;
padding: 24px;
}
.sm-16__heading {
font-size: 20px;
font-weight: 800;
margin-bottom: 6px;
}
.sm-16__sub {
font-size: 13px;
color: var(--muted2);
line-height: 1.7;
margin-bottom: 22px;
}
.sm-16__docs {
display: flex;
flex-direction: column;
gap: 10px;
}
.sm-16__doc-card {
background: var(--surface);
border: 1px solid var(--border);
border-radius: 10px;
padding: 14px 16px;
display: flex;
align-items: center;
gap: 12px;
cursor: pointer;
transition: border-color 0.2s, box-shadow 0.2s;
}
.sm-16__doc-card:hover {
border-color: var(--accent2);
box-shadow: 0 2px 12px rgba(37,99,235,0.08);
}
.sm-16__doc-icon {
width: 34px;
height: 34px;
border-radius: 8px;
background: rgba(37,99,235,0.08);
display: flex;
align-items: center;
justify-content: center;
font-size: 16px;
flex-shrink: 0;
}
.sm-16__doc-title {
font-size: 13px;
font-weight: 700;
margin-bottom: 2px;
}
.sm-16__doc-sub {
font-size: 12px;
color: var(--muted);
}
@media (prefers-reduced-motion: reduce) {
.sm-16__items,
.sm-16__chevron {
transition: none;
}
}
```Here's a working CSS Side Menu 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-Only Accordion Side Navigation
Source: https://codefronts.com/navigation/css-side-menu/css-only-accordion-side-navigation/
A documentation-style sidebar where multiple independent accordion sections can be expanded or collapsed simultaneously using hidden checkboxes and max-height transitions.
## HTML
```html
<div class="sm-16">
<nav class="sm-16__nav">
<div class="sm-16__brand">
<div class="sm-16__logo">D</div>
<div>
<span class="sm-16__brand-name">DocBase</span>
<span class="sm-16__brand-version">v3.2</span>
</div>
</div>
<div class="sm-16__search">
<input type="text" class="sm-16__search-input" placeholder="Search docs…">
</div>
<a class="sm-16__flat" href="#"><span class="sm-16__flat-icon">⬡</span> Overview</a>
<!-- Accordion 1 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a1" checked>
<label class="sm-16__section-header" for="sm-16-a1">
<span><span class="sm-16__section-header-icon">◈</span> Getting Started</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item sm-16__item--active" href="#">Installation</a>
<a class="sm-16__item" href="#">Configuration</a>
<a class="sm-16__item" href="#">Quick Start</a>
<a class="sm-16__item" href="#">Examples</a>
</div>
</div>
<!-- Accordion 2 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a2">
<label class="sm-16__section-header" for="sm-16-a2">
<span><span class="sm-16__section-header-icon">▦</span> Core Concepts</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Architecture</a>
<a class="sm-16__item" href="#">Data Flow</a>
<a class="sm-16__item" href="#">State Management</a>
<a class="sm-16__item" href="#">Routing</a>
</div>
</div>
<!-- Accordion 3 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a3">
<label class="sm-16__section-header" for="sm-16-a3">
<span><span class="sm-16__section-header-icon">◉</span> API Reference</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Endpoints <span class="sm-16__item-badge">48</span></a>
<a class="sm-16__item" href="#">Authentication</a>
<a class="sm-16__item" href="#">Webhooks</a>
<a class="sm-16__item" href="#">Rate Limits</a>
</div>
</div>
<!-- Accordion 4 -->
<div class="sm-16__section">
<input type="checkbox" class="sm-16__acc-toggle" id="sm-16-a4">
<label class="sm-16__section-header" for="sm-16-a4">
<span><span class="sm-16__section-header-icon">◬</span> Guides</span>
<span class="sm-16__chevron">›</span>
</label>
<div class="sm-16__items">
<a class="sm-16__item" href="#">Deployment</a>
<a class="sm-16__item" href="#">Performance</a>
<a class="sm-16__item" href="#">Security</a>
</div>
</div>
<a class="sm-16__flat" href="#"><span class="sm-16__flat-icon">⬙</span> Changelog</a>
</nav>
<div class="sm-16__main">
<div class="sm-16__heading">Documentation</div>
<div class="sm-16__sub">CSS-only accordion sidebar: each section uses a hidden <code>checkbox</code> and <code>max-height</code> transition. Clicking a header expands/collapses its items independently.</div>
<div class="sm-16__docs">
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">📦</div>
<div>
<div class="sm-16__doc-title">Installation Guide</div>
<div class="sm-16__doc-sub">Set up your environment in under 5 minutes</div>
</div>
</div>
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">⚙️</div>
<div>
<div class="sm-16__doc-title">Configuration Reference</div>
<div class="sm-16__doc-sub">All available options with examples</div>
</div>
</div>
<div class="sm-16__doc-card">
<div class="sm-16__doc-icon">🚀</div>
<div>
<div class="sm-16__doc-title">Quick Start Tutorial</div>
<div class="sm-16__doc-sub">Build your first integration in 10 steps</div>
</div>
</div>
</div>
</div>
</div>
```
## CSS
```css
.sm-16,
.sm-16 *,
.sm-16 *::before,
.sm-16 *::after {
box-sizing: border-box;
margin: 0;
padding: 0;
}
.sm-16 ::selection {
background: #2563eb;
color: #fff;
}
.sm-16 {
--bg: #f0f4ff;
--surface: #fff;
--nav-bg: #fff;
--accent: #2563eb;
--accent2: #60a5fa;
--text: #0f172a;
--muted: #94a3b8;
--muted2: #64748b;
--border: #e2e8f0;
--border-active: rgba(37,99,235,0.15);
--font: 'Plus Jakarta Sans', system-ui, sans-serif;
font-family: var(--font);
background: var(--bg);
color: var(--text);
display: flex;
min-height: 100vh;
border-radius: 12px;
overflow: hidden;
}
/* Accordion hidden radio/checkboxes */
.sm-16__acc-toggle {
display: none;
}
/* Sidebar */
.sm-16__nav {
width: 240px;
background: var(--nav-bg);
border-right: 1px solid var(--border);
display: flex;
flex-direction: column;
flex-shrink: 0;
overflow-y: auto;
}
.sm-16__nav::-webkit-scrollbar {
width: 3px;
}
.sm-16__nav::-webkit-scrollbar-thumb {
background: var(--border);
border-radius: 3px;
}
.sm-16__brand {
padding: 18px 16px;
border-bottom: 1px solid var(--border);
display: flex;
align-items: center;
gap: 10px;
flex-shrink: 0;
}
.sm-16__logo {
width: 32px;
height: 32px;
background: var(--accent);
border-radius: 8px;
display: flex;
align-items: center;
justify-content: center;
font-weight: 800;
color: #fff;
font-size: 14px;
}
.sm-16__brand-name {
font-size: 14px;
font-weight: 800;
}
.sm-16__brand-version {
font-size: 10px;
color: var(--muted);
margin-left: 4px;
font-weight: 500;
}
/* Search bar */
.sm-16__search {
padding: 10px 14px;
border-bottom: 1px solid var(--border);
flex-shrink: 0;
}
.sm-16__search-input {
width: 100%;
padding: 7px 12px;
background: var(--bg);
border: 1px solid var(--border);
border-radius: 7px;
font-size: 12px;
font-family: var(--font);
color: var(--text);
outline: none;
}
.sm-16__search-input:focus {
border-color: var(--accent2);
}
/* Accordion section */
.sm-16__section {
border-bottom: 1px solid var(--border);
}
/* Section header — label acts as click target */
.sm-16__section-header {
display: flex;
align-items: center;
justify-content: space-between;
padding: 12px 16px;
cursor: pointer;
user-select: none;
transition: background 0.15s;
font-size: 12px;
font-weight: 700;
text-transform: uppercase;
letter-spacing: 0.1em;
color: var(--muted2);
}
.sm-16__section-header:hover {
background: rgba(37,99,235,0.04);
}
.sm-16__section-header-icon {
font-size: 14px;
}
/* Chevron */
.sm-16__chevron {
font-size: 12px;
color: var(--muted);
transition: transform 0.3s cubic-bezier(0.4,0,0.2,1);
display: inline-block;
}
.sm-16__acc-toggle:checked + .sm-16__section-header .sm-16__chevron {
transform: rotate(90deg);
}
.sm-16__acc-toggle:checked + .sm-16__section-header {
color: var(--accent);
}
/* Collapsible sub-items */
.sm-16__items {
max-height: 0;
overflow: hidden;
transition: max-height 0.38s cubic-bezier(0.4,0,0.2,1);
}
.sm-16__acc-toggle:checked + .sm-16__section-header + .sm-16__items {
max-height: 400px;
}
/* Individual link items */
.sm-16__item {
display: flex;
align-items: center;
gap: 10px;
padding: 9px 16px 9px 36px;
color: var(--muted2);
font-size: 13px;
font-weight: 600;
cursor: pointer;
text-decoration: none;
transition: all 0.15s;
position: relative;
}
.sm-16__item::before {
content: '';
position: absolute;
left: 20px;
top: 50%;
transform: translateY(-50%);
width: 4px;
height: 4px;
border-radius: 50%;
background: var(--muted);
transition: background 0.15s, transform 0.15s;
}
.sm-16__item:hover {
color: var(--accent);
background: rgba(37,99,235,0.05);
}
.sm-16__item:hover::before {
background: var(--accent);
transform: translateY(-50%) scale(1.4);
}
.sm-16__item--active {
color: var(--accent);
background: rgba(37,99,235,0.07);
}
.sm-16__item--active::before {
background: var(--accent);
}
.sm-16__item-badge {
margin-left: auto;
background: rgba(37,99,235,0.12);
color: var(--accent);
font-size: 10px;
font-weight: 700;
padding: 1px 6px;
border-radius: 99px;
}
/* Flat link */
.sm-16__flat {
display: flex;
align-items: center;
gap: 10px;
padding: 11px 16px;
color: var(--muted2);
font-size: 13px;
font-weight: 600;
cursor: pointer;
text-decoration: none;
transition: all 0.15s;
border-bottom: 1px solid var(--border);
}
.sm-16__flat:hover {
color: var(--accent);
background: rgba(37,99,235,0.04);
}
.sm-16__flat-icon {
font-size: 14px;
}
/* Main */
.sm-16__main {
flex: 1;
padding: 24px;
}
.sm-16__heading {
font-size: 20px;
font-weight: 800;
margin-bottom: 6px;
}
.sm-16__sub {
font-size: 13px;
color: var(--muted2);
line-height: 1.7;
margin-bottom: 22px;
}
.sm-16__docs {
display: flex;
flex-direction: column;
gap: 10px;
}
.sm-16__doc-card {
background: var(--surface);
border: 1px solid var(--border);
border-radius: 10px;
padding: 14px 16px;
display: flex;
align-items: center;
gap: 12px;
cursor: pointer;
transition: border-color 0.2s, box-shadow 0.2s;
}
.sm-16__doc-card:hover {
border-color: var(--accent2);
box-shadow: 0 2px 12px rgba(37,99,235,0.08);
}
.sm-16__doc-icon {
width: 34px;
height: 34px;
border-radius: 8px;
background: rgba(37,99,235,0.08);
display: flex;
align-items: center;
justify-content: center;
font-size: 16px;
flex-shrink: 0;
}
.sm-16__doc-title {
font-size: 13px;
font-weight: 700;
margin-bottom: 2px;
}
.sm-16__doc-sub {
font-size: 12px;
color: var(--muted);
}
@media (prefers-reduced-motion: reduce) {
.sm-16__items,
.sm-16__chevron {
transition: none;
}
}
```How this works
Each accordion section groups a hidden <input type="checkbox">, a <label> section header, and the collapsible items container as adjacent siblings. The CSS chain .acc-toggle:checked + .section-header + .items targets the items container when its preceding checkbox is checked, transitioning max-height from 0 to 400px.
The chevron on each section header uses :checked + .section-header .chevron to rotate 90° on expansion. Section header colour also updates via the same selector chain for clear visual feedback. Multiple sections can be open simultaneously since each uses an independent checkbox rather than a shared radio group.
Make it yours
- Switch from
checkboxtoradioinputs with the samenameattribute to make sections mutually exclusive — true accordion behaviour. - Add a fold-and-indent reveal by transitioning
padding-leftfrom 0 to the full indent value alongsidemax-height. - Pre-open specific sections on page load by adding the
checkedattribute to the relevant checkbox in HTML — no JS required. - Add a search filter input that uses JS to hide non-matching items — accordion CSS handles expand/collapse while JS handles only filtering.
- Use CSS Counter to auto-number visible items:
counter-increment: itemon each link andcontent: counter(item)in its::before.
Gotchas — read before shipping
- All three elements — input, label, items — must be adjacent siblings in exact order; any wrapper between them breaks the selector chain.
max-heighttransitions suffer from the magic-number problem — prefergrid-template-rows: 0fr / 1frin modern browsers for transition to true content height.- Checkbox state in sidebar accordions can conflict with form submission if inside a
<form>— always usetype="checkbox"with nonameattribute to exclude from form data.
Browser support
| Chrome | Safari | Firefox | Edge |
|---|---|---|---|
| 26+ | 7+ | 20+ | 26+ |
:checked sibling combinator and max-height transitions are universally supported in all modern browsers and IE9+.