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

body {
  font-family: Inter, system-ui, Arial, sans-serif;
  background: #f0f2f5;
  min-height: 100vh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 40px 16px;
}

#app {
  width: 100%;
  max-width: 600px;
}

h1 {
  font-size: 14px;
  font-weight: 600;
  color: #888;
  letter-spacing: .08em;
  text-transform: uppercase;
  margin-bottom: 16px;
}

.tabs {
  background: #fff;
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0,0,0,.08);
  overflow: hidden;
}

/* ── header bar ─────────────────────────────── */
.tabs__bar {
  display: flex;
  border-bottom: 1px solid #e5e7eb;
  background: #f8f9fb;
  overflow-x: auto;
  scrollbar-width: none;
}

.tabs__bar::-webkit-scrollbar { display: none; }

.tabs__tab {
  padding: 10px 20px;
  font-size: 14px;
  font-weight: 500;
  color: #666;
  cursor: pointer;
  white-space: nowrap;
  border: none;
  background: none;
  border-bottom: 2px solid transparent;
  transition: color .15s, border-color .15s;
  user-select: none;
}

.tabs__tab:hover {
  color: #333;
  background: #eef0f3;
}

.tabs__tab.active {
  color: #1a73e8;
  border-bottom-color: #1a73e8;
  background: #fff;
}

/* ── panel ───────────────────────────────────── */
.tabs__panel {
  padding: 24px;
  min-height: 140px;
  font-size: 15px;
  line-height: 1.7;
  color: #333;
}
tabs

Source
