:root {
  color-scheme: light;
  --ink: #17221c;
  --muted: #5f6d65;
  --paper: #fffdf8;
  --canvas: #f0efe5;
  --green: #176b50;
  --green-dark: #0e4d39;
  --green-soft: #dceee5;
  --gold: #f2bb4d;
  --gold-soft: #fff3d4;
  --border: #ccd3cc;
  --danger: #a13a2a;
  --shadow: 0 22px 60px rgb(27 48 37 / 12%);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 15% 10%, rgb(242 187 77 / 20%), transparent 28rem),
    var(--canvas);
}

button,
input {
  font: inherit;
}

button {
  touch-action: manipulation;
}

.page-shell {
  width: min(100% - 2rem, 48rem);
  margin: 0 auto;
  padding: 3.5rem 0 2rem;
}

.hero {
  max-width: 42rem;
  margin-bottom: 2rem;
}

.eyebrow,
.section-label,
.step-kicker {
  margin: 0 0 0.5rem;
  color: var(--green);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

h1,
h2,
p {
  text-wrap: pretty;
}

h1 {
  max-width: 12ch;
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(2.7rem, 10vw, 5rem);
  font-weight: 600;
  letter-spacing: -0.05em;
  line-height: 0.95;
}

.hero-copy {
  max-width: 38rem;
  margin: 1.25rem 0 0;
  color: var(--muted);
  font-size: 1.08rem;
  line-height: 1.65;
}

.public-parameters {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  margin-bottom: 1rem;
  padding: 1rem 1.25rem;
  border: 1px solid var(--border);
  border-radius: 1rem;
  background: rgb(255 253 248 / 65%);
}

.section-label {
  margin-bottom: 0.2rem;
}

.parameter-explanation {
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.parameter-list {
  display: flex;
  flex: none;
  gap: 0.6rem;
  margin: 0;
}

.parameter-list div {
  min-width: 5.7rem;
  padding: 0.55rem 0.7rem;
  border-radius: 0.75rem;
  background: var(--paper);
  text-align: center;
}

.parameter-list dt {
  color: var(--muted);
  font-size: 0.67rem;
  font-weight: 700;
  text-transform: uppercase;
}

.parameter-list dd {
  margin: 0.1rem 0 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.7rem;
  font-weight: 700;
}

.demo-card {
  overflow: hidden;
  border: 1px solid rgb(204 211 204 / 80%);
  border-radius: 1.35rem;
  background: var(--paper);
  box-shadow: var(--shadow);
}

.progress {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  margin: 0;
  padding: 0;
  border-bottom: 1px solid var(--border);
  list-style: none;
}

.progress-step {
  padding: 0.9rem;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 700;
  text-align: center;
}

.progress-step + .progress-step {
  border-left: 1px solid var(--border);
}

.progress-step span {
  display: inline-grid;
  width: 1.45rem;
  height: 1.45rem;
  margin-right: 0.25rem;
  border: 1px solid var(--border);
  border-radius: 50%;
  place-items: center;
}

.progress-step.is-current {
  color: var(--green-dark);
  background: var(--green-soft);
}

.progress-step.is-complete span {
  border-color: var(--green);
  color: white;
  background: var(--green);
}

.step {
  padding: clamp(1.4rem, 5vw, 2.5rem);
}

.step[hidden] {
  display: none;
}

.step h2 {
  margin: 0 0 0.75rem;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(1.8rem, 6vw, 2.65rem);
  font-weight: 600;
  letter-spacing: -0.03em;
}

.step > p:not(.step-kicker, .spoken-prompt) {
  max-width: 38rem;
  margin: 0 0 1.75rem;
  color: var(--muted);
  line-height: 1.6;
}

.safe-to-share::before {
  content: "✓";
  margin-right: 0.35rem;
}

.number-form {
  display: grid;
  gap: 0.7rem;
  margin-top: 1.75rem;
}

.number-form label {
  font-weight: 750;
}

.number-entry {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 0.65rem;
}

input[type="number"] {
  width: 100%;
  min-height: 3.2rem;
  padding: 0.65rem 0.85rem;
  border: 1px solid #9da9a0;
  border-radius: 0.65rem;
  color: var(--ink);
  background: white;
  font-size: 1.15rem;
}

input[type="number"]:focus {
  border-color: var(--green);
  outline: 3px solid rgb(23 107 80 / 18%);
}

.button {
  min-height: 3.2rem;
  padding: 0.7rem 1rem;
  border: 1px solid transparent;
  border-radius: 0.65rem;
  font-weight: 750;
  cursor: pointer;
}

.button-primary {
  color: white;
  background: var(--green);
}

.button-primary:hover {
  background: var(--green-dark);
}

.button-secondary {
  border-color: var(--border);
  color: var(--green-dark);
  background: white;
}

.button-secondary:hover {
  border-color: var(--green);
  background: var(--green-soft);
}

.button-wide {
  width: 100%;
  margin-top: 0.45rem;
}

.form-hint,
.form-error {
  min-height: 1.2em;
  margin: 0;
  font-size: 0.86rem;
}

.form-hint {
  color: var(--muted);
}

.form-error {
  color: var(--danger);
  font-weight: 650;
}

.public-number-display,
.secret-display {
  display: grid;
  padding: 1.35rem;
  border-radius: 1rem;
  text-align: center;
}

.public-number-display {
  color: var(--green-dark);
  background: var(--green-soft);
}

.public-number-display span,
.secret-display span {
  font-size: 0.8rem;
  font-weight: 800;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.public-number-display strong,
.secret-display strong {
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(4rem, 20vw, 7rem);
  line-height: 1;
}

.spoken-prompt {
  margin: 1rem 0 2rem;
  color: var(--green-dark);
  text-align: center;
}

.exchange-form {
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

.secret-display {
  margin: 1.75rem 0;
  color: #4c3509;
  background: var(--gold-soft);
  box-shadow: inset 0 0 0 1px rgb(242 187 77 / 55%);
}

.explanation {
  margin: 1rem 0;
  border: 1px solid var(--border);
  border-radius: 0.8rem;
}

.explanation summary {
  padding: 1rem;
  font-weight: 750;
  cursor: pointer;
}

.explanation > p,
.transcript {
  margin: 0;
  padding: 0 1rem 1rem;
  color: var(--muted);
  line-height: 1.55;
}

.transcript p {
  margin-bottom: 0.5rem;
  color: var(--ink);
  font-weight: 700;
}

.transcript ul {
  margin: 0;
  padding-left: 1.4rem;
}

.warning {
  margin: 1rem 0;
  padding: 1rem;
  border-left: 4px solid var(--gold);
  border-radius: 0.4rem;
  background: var(--gold-soft);
}

.warning p {
  margin: 0.25rem 0 0;
  color: #614b1e;
  font-size: 0.9rem;
  line-height: 1.5;
}

footer {
  padding: 1.5rem 0 0;
  color: var(--muted);
  font-size: 0.8rem;
  text-align: center;
}

@media (max-width: 36rem) {
  .page-shell {
    padding-top: 2rem;
  }

  .public-parameters {
    align-items: stretch;
    flex-direction: column;
  }

  .parameter-list div {
    flex: 1;
  }

  .number-entry {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: no-preference) {
  .step:not([hidden]) {
    animation: enter 250ms ease-out;
  }

  @keyframes enter {
    from {
      opacity: 0;
      transform: translateY(0.35rem);
    }
  }
}