Button

Buttons carry more state than they look like they do — variants, sizes, disabled, and (the one part that needs JS) a loading state for actions that take time.

Pseudocode

Structure

• A single <button> (or <a class="btn"> when it navigates instead of acting) — classes control everything else, the element stays the same.

Style

• A base .btn class for the shared shape and spacing, then modifier classes (.btn-primary, .btn-outline, .btn-sm/.btn-lg) that only touch color or size — the classic “base + modifier” pattern.
• :disabled needs its own dimmed, no-cursor styling; the browser’s default disabled look is barely noticeable.

Features

• Variants and sizes are pure CSS.
• A “loading” state (spinner + disabled, so a slow action can’t be double-submitted) needs a little JS to toggle it on click and back off once the action resolves.

Button variants

Previewindex.htmlstyle.css

<div class="btn-row">
    <button class="btn btn-primary">Primary</button>
    <button class="btn btn-secondary">Secondary</button>
    <button class="btn btn-outline">Outline</button>
    <button class="btn btn-ghost">Ghost</button>
    <button class="btn btn-primary" disabled>Disabled</button>
</div>
<div class="btn-row">
    <button class="btn btn-primary btn-sm">Small</button>
    <button class="btn btn-primary">Medium</button>
    <button class="btn btn-primary btn-lg">Large</button>
</div>

.btn-row {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-bottom: 0.6rem;
}
 
.btn {
    padding: 0.5rem 1rem;
    border-radius: 6px;
    border: 1px solid transparent;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
}
 
.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}
 
.btn-primary {
    background: #6366f1;
    color: white;
}
 
.btn-secondary {
    background: #1e293b;
    color: white;
}
 
.btn-outline {
    background: none;
    border-color: #6366f1;
    color: #6366f1;
}
 
.btn-ghost {
    background: none;
    color: #6366f1;
}
 
.btn-ghost:hover {
    background: #eef2ff;
}
 
.btn-sm {
    padding: 0.3rem 0.7rem;
    font-size: 0.75rem;
}
 
.btn-lg {
    padding: 0.7rem 1.3rem;
    font-size: 0.95rem;
}

Button with a loading state

Clicking disables the button and swaps its label for a spinner + “Saving…”, so a slow action can’t fire twice. The setTimeout here stands in for a real request — swap it for whatever await fetch(...) resolves.

Previewindex.htmlstyle.cssscript.js

<button class="btn btn-primary" id="lb-btn">
    <span class="btn-spinner" id="lb-spinner" hidden></span>
    <span id="lb-label">Save changes</span>
</button>

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    border: none;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
}
 
.btn:disabled {
    opacity: 0.7;
    cursor: default;
}
 
.btn-primary {
    background: #6366f1;
    color: white;
}
 
.btn-spinner {
    width: 0.9rem;
    height: 0.9rem;
    border: 2px solid rgba(255, 255, 255, 0.4);
    border-top-color: white;
    border-radius: 50%;
    animation: btn-spin 0.6s linear infinite;
}
 
@keyframes btn-spin {
    to {
        transform: rotate(360deg);
    }
}

const btn = document.getElementById("lb-btn");
const spinner = document.getElementById("lb-spinner");
const label = document.getElementById("lb-label");
 
if (btn && spinner && label) {
    btn.onclick = () => {
        btn.disabled = true;
        spinner.hidden = false;
        label.textContent = "Saving…";
 
        // stand-in for a real request — swap this for a fetch() in practice
        setTimeout(() => {
            btn.disabled = false;
            spinner.hidden = true;
            label.textContent = "Save changes";
        }, 1500);
    };
}