Custom Focus Ring

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* Global focus ring — applied via :focus-visible */
:focus {
  outline: none;
}
:focus-visible {
  outline: 2.5px solid #6366f1;
  outline-offset: 3px;
  border-radius: 6px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #0d1117;
  color: #e6edf3;
  min-height: 100vh;
  padding: 32px 16px;
  display: flex;
  justify-content: center;
}

.demo {
  width: 100%;
  max-width: 720px;
}

.section-title {
  font-size: 20px;
  font-weight: 800;
  margin-bottom: 8px;
}
.section-desc {
  font-size: 14px;
  color: #8b949e;
  margin-bottom: 28px;
  line-height: 1.6;
}

kbd {
  background: #21262d;
  border: 1px solid #30363d;
  border-bottom-width: 2px;
  border-radius: 5px;
  padding: 1px 6px;
  font-size: 12px;
  font-family: Menlo, monospace;
  color: #e6edf3;
}

.ring-showcase {
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.ring-group {
}
.ring-group-title {
  font-size: 11px;
  font-weight: 700;
  color: #4a555f;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 12px;
}

.ring-row {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  align-items: center;
}
.ring-col {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

/* Buttons */
.demo-btn {
  padding: 9px 20px;
  border: none;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.15s;
}
.demo-btn:hover {
  opacity: 0.85;
}
.demo-btn--primary {
  background: #6366f1;
  color: #fff;
}
.demo-btn--secondary {
  background: #21262d;
  color: #e6edf3;
  border: 1px solid #30363d;
}
.demo-btn--danger {
  background: #f85149;
  color: #fff;
}
.demo-btn--ghost {
  background: transparent;
  color: #8b949e;
  border: 1px solid #30363d;
}
.demo-btn--danger:focus-visible {
  outline-color: #f85149;
}
.demo-btn--primary:focus-visible {
  outline-color: #818cf8;
}

/* Inputs */
.demo-input,
.demo-textarea,
.demo-select {
  background: #161b22;
  border: 1px solid #30363d;
  border-radius: 8px;
  color: #e6edf3;
  font-size: 14px;
  padding: 9px 12px;
  width: 100%;
  max-width: 380px;
  outline: none;
  font-family: inherit;
  transition: border-color 0.15s;
}
.demo-input:focus-visible,
.demo-textarea:focus-visible,
.demo-select:focus-visible {
  border-color: #6366f1;
  outline: 2.5px solid rgba(99, 102, 241, 0.4);
  outline-offset: 2px;
}
.demo-input::placeholder,
.demo-textarea::placeholder {
  color: #4a555f;
}
.demo-textarea {
  resize: vertical;
  min-height: 80px;
}

/* Links */
.demo-link {
  color: #6366f1;
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  border-bottom: 1px solid rgba(99, 102, 241, 0.3);
}
.demo-link:hover {
  border-bottom-color: #6366f1;
}
.demo-link--subtle {
  color: #8b949e;
  border-bottom-color: transparent;
}
.demo-link--subtle:hover {
  color: #e6edf3;
}

/* Card links */
.demo-card-link {
  display: block;
  background: #161b22;
  border: 1px solid #21262d;
  border-radius: 10px;
  padding: 14px 18px;
  text-decoration: none;
  transition: border-color 0.15s, transform 0.15s;
  min-width: 160px;
}
.demo-card-link:hover {
  border-color: #30363d;
  transform: translateY(-1px);
}
.demo-card-link:focus-visible {
  outline-offset: 4px;
}
.dcl-title {
  font-size: 14px;
  font-weight: 600;
  color: #e6edf3;
  margin-bottom: 4px;
}
.dcl-sub {
  font-size: 12px;
  color: #6c7086;
}

/* Checkboxes */
.demo-checkbox,
.demo-radio {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  color: #8b949e;
  cursor: pointer;
}
.demo-checkbox input,
.demo-radio input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.cb-custom {
  width: 18px;
  height: 18px;
  border: 2px solid #30363d;
  border-radius: 5px;
  background: #161b22;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s;
  position: relative;
}
.demo-checkbox input:checked + .cb-custom {
  background: #6366f1;
  border-color: #6366f1;
}
.demo-checkbox input:checked + .cb-custom::after {
  content: "";
  width: 10px;
  height: 6px;
  border-left: 2px solid #fff;
  border-bottom: 2px solid #fff;
  transform: rotate(-45deg) translateY(-1px);
  display: block;
}
.demo-checkbox input:focus-visible + .cb-custom {
  outline: 2.5px solid #6366f1;
  outline-offset: 2px;
}

.rb-custom {
  width: 18px;
  height: 18px;
  border: 2px solid #30363d;
  border-radius: 50%;
  background: #161b22;
  flex-shrink: 0;
  position: relative;
  transition: all 0.15s;
}
.demo-radio input:checked + .rb-custom {
  border-color: #6366f1;
}
.demo-radio input:checked + .rb-custom::after {
  content: "";
  position: absolute;
  inset: 3px;
  background: #6366f1;
  border-radius: 50%;
}
.demo-radio input:focus-visible + .rb-custom {
  outline: 2.5px solid #6366f1;
  outline-offset: 2px;
}

// Show "mouse" vs "keyboard" mode indicator
let usingKeyboard = false;

document.addEventListener("keydown", (e) => {
  if (e.key === "Tab") usingKeyboard = true;
});

document.addEventListener("mousedown", () => {
  usingKeyboard = false;
});

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Custom Focus Ring</title>
  <link rel="stylesheet" href="style.css" />
</head>
<body>
<div class="demo">
  <h2 class="section-title">Custom Focus Ring System</h2>
  <p class="section-desc">Press <kbd>Tab</kbd> to navigate. All interactive elements use a consistent, high-contrast focus ring.</p>

  <div class="ring-showcase">

    <div class="ring-group">
      <h3 class="ring-group-title">Buttons</h3>
      <div class="ring-row">
        <button class="demo-btn demo-btn--primary">Primary</button>
        <button class="demo-btn demo-btn--secondary">Secondary</button>
        <button class="demo-btn demo-btn--danger">Danger</button>
        <button class="demo-btn demo-btn--ghost">Ghost</button>
      </div>
    </div>

    <div class="ring-group">
      <h3 class="ring-group-title">Inputs</h3>
      <div class="ring-col">
        <input class="demo-input" type="text" placeholder="Text input" />
        <textarea class="demo-textarea" placeholder="Textarea" rows="3"></textarea>
        <select class="demo-select">
          <option>Select option…</option>
          <option>Option A</option>
          <option>Option B</option>
        </select>
      </div>
    </div>

    <div class="ring-group">
      <h3 class="ring-group-title">Links & Cards</h3>
      <div class="ring-row">
        <a class="demo-link" href="#">Documentation →</a>
        <a class="demo-link demo-link--subtle" href="#">Subtle link</a>
      </div>
      <div class="ring-row" style="margin-top:12px">
        <a class="demo-card-link" href="#">
          <p class="dcl-title">Card link</p>
          <p class="dcl-sub">Entire card is focusable</p>
        </a>
        <a class="demo-card-link" href="#">
          <p class="dcl-title">Another card</p>
          <p class="dcl-sub">Keyboard accessible</p>
        </a>
      </div>
    </div>

    <div class="ring-group">
      <h3 class="ring-group-title">Checkboxes & Radios</h3>
      <div class="ring-col">
        <label class="demo-checkbox">
          <input type="checkbox" checked />
          <span class="cb-custom"></span>
          Receive notifications
        </label>
        <label class="demo-checkbox">
          <input type="checkbox" />
          <span class="cb-custom"></span>
          Subscribe to newsletter
        </label>
        <label class="demo-radio">
          <input type="radio" name="plan" checked />
          <span class="rb-custom"></span>
          Free plan
        </label>
        <label class="demo-radio">
          <input type="radio" name="plan" />
          <span class="rb-custom"></span>
          Pro plan
        </label>
      </div>
    </div>

  </div>
</div>
<script src="script.js"></script>
</body>
</html>