:root {
  --brand: #10c7bd;
  --brand-dark: #087f79;
  --ink: #111827;
  --muted: #617083;
  --error: #b42318;
  --success: #087f5b;
}

* { box-sizing: border-box; }

body {
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background:
    radial-gradient(circle at 15% 10%, rgba(16,199,189,.19), transparent 32rem),
    radial-gradient(circle at 90% 85%, rgba(16,199,189,.10), transparent 28rem),
    #f7fafc;
}

main {
  min-height: calc(100vh - 64px);
  display: grid;
  place-items: center;
  padding: 32px 20px;
}

.card {
  width: min(780px, 100%);
  padding: clamp(30px, 6vw, 64px);
  text-align: center;
  background: rgba(255,255,255,.94);
  border: 1px solid rgba(17,24,39,.08);
  border-radius: 32px;
  box-shadow: 0 24px 70px rgba(17,24,39,.10);
}

.logo {
  display: block;
  width: min(460px, 92%);
  height: auto;
  margin: 0 auto 26px;
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--brand-dark);
  font-size: .78rem;
  font-weight: 800;
  letter-spacing: .18em;
}

h1 {
  margin: 0;
  font-size: clamp(2.3rem, 7vw, 4.7rem);
  line-height: .98;
  letter-spacing: -.055em;
}

.intro {
  max-width: 620px;
  margin: 24px auto 0;
  color: var(--muted);
  font-size: clamp(1.05rem, 2.2vw, 1.28rem);
  line-height: 1.7;
}

.topics {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  margin: 30px 0;
}

.topics span {
  padding: 10px 14px;
  color: var(--brand-dark);
  font-size: .92rem;
  font-weight: 700;
  background: rgba(16,199,189,.10);
  border: 1px solid rgba(16,199,189,.20);
  border-radius: 999px;
}

.signup {
  margin-top: 34px;
  padding-top: 32px;
  border-top: 1px solid rgba(17,24,39,.09);
}

.signup h2 {
  margin: 0;
  font-size: clamp(1.45rem, 3vw, 2rem);
  letter-spacing: -.03em;
}

.signup > p {
  margin: 12px auto 22px;
  color: var(--muted);
  line-height: 1.6;
}

.fields {
  display: grid;
  grid-template-columns: minmax(0,1fr) auto;
  gap: 10px;
}

input, button {
  min-height: 54px;
  font: inherit;
  border-radius: 14px;
}

input {
  min-width: 0;
  padding: 0 16px;
  color: var(--ink);
  background: white;
  border: 1px solid rgba(17,24,39,.16);
  outline: none;
}

input:focus {
  border-color: var(--brand);
  box-shadow: 0 0 0 4px rgba(16,199,189,.16);
}

button {
  padding: 0 22px;
  color: #062b29;
  font-weight: 800;
  background: var(--brand);
  border: 0;
  cursor: pointer;
}

button:hover:not(:disabled) { background: #20d5cb; }
button:disabled { opacity: .65; cursor: wait; }

small {
  display: block;
  margin-top: 13px;
  color: #7b8492;
}

.message {
  min-height: 24px;
  margin: 13px 0 0;
  font-weight: 700;
}

.message.success { color: var(--success); }
.message.error { color: var(--error); }

footer {
  min-height: 64px;
  display: grid;
  place-items: center;
  padding: 16px;
  color: #7b8492;
  font-size: .86rem;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
}

@media (max-width: 640px) {
  .card { border-radius: 24px; }
  .fields { grid-template-columns: 1fr; }
  button { width: 100%; }
}