:root {
  --bg: #f4f6fb;
  --card: #ffffff;
  --text: #202124;
  --muted: #5f6368;
  --line: #dadce0;
  --shadow: 0 1px 3px rgba(60, 64, 67, 0.15), 0 4px 12px rgba(60, 64, 67, 0.1);
  --radius: 28px;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  font-family: Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
}

.page-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}

.signin-card {
  width: min(100%, 450px);
  padding: 48px 40px 32px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  box-shadow: var(--shadow);
  text-align: center;
}

.brand-mark {
  width: 44px;
  height: 44px;
  margin: 0 auto 28px;
}

.brand-mark img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 5vw, 2.35rem);
  font-weight: 500;
  line-height: 1.18;
}

.signin-copy {
  margin: 14px 0 28px;
  font-size: 1rem;
  line-height: 1.5;
  color: var(--muted);
}

.google-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  width: 100%;
  min-height: 48px;
  padding: 0 16px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #ffffff;
  color: var(--text);
  font: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 120ms ease, box-shadow 120ms ease;
}

.google-button:disabled {
  cursor: wait;
  opacity: 0.72;
}

.google-button:hover {
  background: #f8f9fa;
}

.google-button:focus-visible {
  outline: 2px solid #1a73e8;
  outline-offset: 2px;
}

.google-icon {
  display: inline-grid;
  place-items: center;
  width: 16px;
  height: 16px;
}

.google-icon img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.button-help {
  margin: 16px 0 0;
  font-size: 0.85rem;
  line-height: 1.5;
  color: var(--muted);
}

.button-help code {
  font-family: Consolas, monospace;
  font-size: 0.9em;
}

.private-card {
  text-align: center;
}

.private-avatar {
  width: 72px;
  height: 72px;
  margin: 0 auto 16px;
  border-radius: 999px;
}

.private-name {
  margin: 0 0 8px;
  font-size: 1.15rem;
  font-weight: 600;
}

.private-meta {
  margin: 0 0 8px;
  color: var(--muted);
  word-break: break-word;
}

.secondary-button {
  margin-top: 16px;
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 24px;
  transform: translateX(-50%) translateY(18px);
  padding: 12px 16px;
  border-radius: 999px;
  background: rgba(32, 33, 36, 0.94);
  color: #fff;
  font-size: 0.9rem;
  opacity: 0;
  pointer-events: none;
  transition: opacity 160ms ease, transform 160ms ease;
}

.toast.is-visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

@media (max-width: 640px) {
  .signin-card {
    padding: 36px 24px 24px;
    border-radius: 20px;
  }
}