:root {
  --bg: #f5f7fb;
  --text: #0f172a;
  --muted: rgba(15, 23, 42, 0.72);
  --border: rgba(15, 23, 42, 0.14);
  --card: #ffffff;
  --card-shadow: 0 12px 30px rgba(15, 23, 42, 0.12);
  --btn-bg: #111827;
  --btn-text: #ffffff;
  --link: #1d4ed8;
  --alert-bg: #fef2f2;
  --alert-border: #fecaca;
  --alert-text: #991b1b;
  --ok-bg: #ecfdf5;
  --ok-border: #a7f3d0;
  --ok-text: #065f46;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.auth {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  width: min(520px, 92vw);
}

.logo {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.logo img {
  width: 58px;
  height: 58px;
  border-radius: 14px;
}

.google-btn {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  background: #fff;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 999px;
  text-decoration: none;
  font-size: 15px;
  font-weight: 500;
  box-shadow: 0 1px 2px rgba(0, 0, 0, .08);
  transition: box-shadow .15s ease, transform .05s ease;
}

.google-btn:hover {
  box-shadow: 0 2px 6px rgba(0,0,0,.15);
}

.google-btn:active {
  transform: translateY(1px);
}

.google-icon {
  width: 18px;
  height: 18px;
}

.card {
  width: 100%;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
  box-shadow: var(--card-shadow);
}

.card h2 {
  margin: 0 0 12px;
  font-size: 1.05rem;
}

.stack {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

label {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: .9rem;
  color: var(--text);
}

input[type="text"],
input[type="email"],
input[type="password"] {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 12px;
  font-size: .95rem;
  background: var(--card);
  color: var(--text);
}

button {
  border: 1px solid var(--btn-bg);
  background: var(--btn-bg);
  color: var(--btn-text);
  border-radius: 8px;
  padding: 10px 12px;
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
}

.remember {
  flex-direction: row;
  align-items: center;
  gap: 8px;
}

.alert {
  width: 100%;
  border: 1px solid var(--alert-border);
  background: var(--alert-bg);
  color: var(--alert-text);
  padding: 10px 12px;
  border-radius: 8px;
  font-size: .9rem;
}

.alert-success {
  border-color: var(--ok-border);
  background: var(--ok-bg);
  color: var(--ok-text);
}

.link-inline {
  color: var(--link);
  text-decoration: none;
  font-size: .9rem;
}

.link-inline:hover {
  text-decoration: underline;
}

.auth-title {
  margin: 0;
  font-size: 1.35rem;
  color: var(--text);
}

.auth-copy {
  margin: 0;
  color: var(--muted);
  line-height: 1.5;
}

.signup-toggle {
  width: 100%;
}

.signup-toggle summary {
  list-style: none;
  cursor: pointer;
  color: var(--link);
  font-size: .95rem;
  font-weight: 600;
  user-select: none;
}

.signup-toggle summary::-webkit-details-marker {
  display: none;
}

.signup-toggle .card {
  margin-top: 10px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b1220;
    --text: rgba(255, 255, 255, 0.94);
    --muted: rgba(255, 255, 255, 0.76);
    --border: rgba(255, 255, 255, 0.12);
    --card: #0f172a;
    --card-shadow: 0 14px 34px rgba(0, 0, 0, 0.46);
    --btn-bg: #e2e8f0;
    --btn-text: #0b1220;
    --link: #93c5fd;
    --alert-bg: rgba(127, 29, 29, 0.22);
    --alert-border: rgba(252, 165, 165, 0.45);
    --alert-text: #fecaca;
    --ok-bg: rgba(6, 95, 70, 0.25);
    --ok-border: rgba(110, 231, 183, 0.45);
    --ok-text: #a7f3d0;
  }

  .google-btn {
    background: #111c33;
  }
}