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

html, body { height: 100%; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: #f4f5f7;
  color: #1f2328;
  display: flex;
  align-items: center;
  justify-content: center;
  -webkit-font-smoothing: antialiased;
}

.card {
  background: #ffffff;
  border: 1px solid #e2e5e9;
  border-radius: 14px;
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.07);
  padding: 46px 48px 36px;
  text-align: center;
  width: min(420px, calc(100% - 32px));
}

h1 {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.sub {
  margin-top: 8px;
  font-size: 14px;
  color: #59626e;
}

.error {
  margin-top: 20px;
  padding: 10px 14px;
  border: 1px solid #f2c2be;
  border-radius: 8px;
  background: #fdefee;
  color: #b3261e;
  font-size: 13px;
  line-height: 1.45;
  text-align: left;
}

.slack-btn {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  margin-top: 26px;
  padding: 13px 26px;
  border-radius: 9px;
  background: #4a154b;
  color: #ffffff;
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  transition: background 0.15s ease;
}

.slack-btn:hover { background: #3b113c; }
.slack-btn:active { background: #320e33; }

.slack-btn:focus-visible {
  outline: 3px solid #9a7ca8;
  outline-offset: 2px;
}

.slack-btn svg {
  width: 20px;
  height: 20px;
  flex: none;
}

.foot {
  margin-top: 24px;
  font-size: 12px;
  color: #8a93a0;
}