:root {
  color-scheme: light;
  --page: #f6f8fc;
  --surface: #ffffff;
  --soft: #f0f4fa;
  --text: #172137;
  --muted: #68758c;
  --border: #dfe6ef;
  --blue: #5366e5;
  --blue-soft: #edf0ff;
  --green: #118d6d;
  --green-soft: #e9f9f4;
  --gold: #b9781b;
  --gold-soft: #fff5df;
  --red: #cc5267;
  --red-soft: #fff0f3;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
  color: var(--text);
  background: var(--page);
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

body {
  margin: 0;
  padding: clamp(12px, 3vw, 32px);
  min-width: 320px;
  background: var(--page);
}

button,
a {
  font: inherit;
}

button:focus-visible,
a:focus-visible {
  outline: 3px solid rgba(83, 102, 229, 0.35);
  outline-offset: 3px;
}

.lesson {
  width: min(1020px, 100%);
  margin: 0 auto;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 22px;
  background: var(--surface);
  box-shadow: 0 24px 64px rgba(44, 53, 80, 0.12);
}

.app-header {
  display: flex;
  align-items: center;
  gap: 14px;
  min-height: 64px;
  padding: 12px 20px;
  border-bottom: 1px solid var(--border);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-weight: 700;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 11px;
  color: #ffffff;
  background: var(--blue);
}

.mode-label {
  margin-left: auto;
  padding: 7px 11px;
  border-radius: 999px;
  color: var(--blue);
  background: var(--blue-soft);
}

.progress-track {
  height: 5px;
  background: var(--border);
}

.progress-track span {
  display: block;
  width: 25%;
  height: 100%;
  background: var(--blue);
  transition: width 220ms ease;
}

.lesson-content {
  padding: clamp(20px, 4vw, 42px);
}

.lesson-meta {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  color: var(--muted);
}

h1 {
  margin: 10px 0 0;
  text-align: center;
  font-size: clamp(1.65rem, 4vw, 2.45rem);
  letter-spacing: -0.035em;
}

.lesson-subtitle {
  max-width: 680px;
  margin: 9px auto 20px;
  color: var(--muted);
  text-align: center;
}

.perspective-bridge {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 10px 14px;
  align-items: start;
  max-width: 820px;
  margin: 0 auto 14px;
  padding: 13px 15px;
  border-left: 4px solid var(--blue);
  border-radius: 8px;
  background: var(--blue-soft);
}

.perspective-bridge > span {
  color: var(--blue);
  font-weight: 700;
}

.perspective-bridge p {
  margin: 0;
  color: var(--muted);
}

.position-ticket {
  max-width: 880px;
  margin: 0 auto 18px;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--surface);
}

.ticket-header {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  align-items: center;
  padding: 14px 17px;
  border-bottom: 1px solid var(--border);
  background: var(--soft);
}

.ticket-header div {
  display: grid;
  gap: 2px;
}

.ticket-header div > span,
.platform-label {
  color: var(--muted);
  font-size: 0.88rem;
}

.ticket-header div > strong {
  font-size: 1.2rem;
}

.ticket-status {
  padding: 6px 9px;
  border-radius: 999px;
  color: var(--blue);
  background: var(--blue-soft);
  white-space: nowrap;
}

.ticket-body {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
}

.platform-contract,
.plain-contract {
  padding: 16px 17px;
}

.plain-contract {
  border-left: 1px solid var(--border);
}

.platform-contract dl {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0 18px;
  margin: 9px 0 0;
}

.platform-contract dl div {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
  padding: 7px 0;
  border-bottom: 1px solid var(--border);
}

.platform-contract dt {
  color: var(--muted);
}

.platform-contract dd {
  display: grid;
  gap: 2px;
  margin: 0;
  text-align: right;
}

.platform-contract dd strong {
  font-weight: 700;
}

.platform-contract dd small {
  max-width: 190px;
  color: var(--muted);
  font-weight: 400;
}

.plain-contract > p {
  margin: 8px 0 0;
  color: var(--text);
}

.ticket-event {
  display: grid;
  gap: 4px;
  margin-top: 12px;
  padding: 10px 12px;
  border-radius: 10px;
  background: var(--gold-soft);
}

.ticket-event span {
  color: var(--gold);
  font-size: 0.88rem;
}

.ticket-ledger {
  margin-top: 11px;
}

.ticket-ledger > div {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
  padding: 7px 0;
  border-bottom: 1px solid var(--border);
}

.ticket-ledger span {
  color: var(--muted);
}

.ticket-ledger strong {
  text-align: right;
}

.ticket-line.active strong {
  color: var(--gold);
}

.ticket-line.complete strong {
  color: var(--green);
}

.ticket-line.loss strong {
  color: var(--red);
}

.interaction {
  min-height: 510px;
  padding: clamp(16px, 3vw, 28px);
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 20px;
  background:
    radial-gradient(circle at 14% 24%, var(--blue-soft), transparent 25%),
    radial-gradient(circle at 87% 78%, var(--green-soft), transparent 27%),
    var(--surface);
}

.roles {
  display: grid;
  grid-template-columns: 1fr 150px 1fr;
  gap: 18px;
  align-items: center;
  max-width: 820px;
  margin: 0 auto 24px;
}

.role,
.clearing-role {
  text-align: center;
}

.role-icon,
.clearing-icon {
  display: grid;
  place-items: center;
  width: 76px;
  height: 76px;
  margin: 0 auto 9px;
  border-radius: 25px;
  color: var(--blue);
  background: var(--blue-soft);
  font-size: 1.35rem;
  font-weight: 700;
}

.operator-role .role-icon {
  color: var(--green);
  background: var(--green-soft);
}

.clearing-icon {
  color: var(--gold);
  background: var(--gold-soft);
  font-size: 1.9rem;
}

.role strong,
.clearing-role strong {
  display: block;
}

.role span,
.clearing-role span {
  color: var(--muted);
}

.stage[hidden] {
  display: none;
}

.stage h2 {
  margin: 0;
  text-align: center;
  font-size: clamp(1.2rem, 3vw, 1.65rem);
}

.foundation-stage {
  max-width: 820px;
  margin: 0 auto;
}

.story-start {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-top: 22px;
}

.story-person,
.story-concern {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 13px;
  align-items: start;
  padding: 17px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--surface);
}

.story-person p,
.story-concern p,
.story-choice p,
.language-translation p {
  margin: 6px 0 0;
  color: var(--muted);
}

.story-avatar,
.story-concern > span {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 14px;
  color: var(--blue);
  background: var(--blue-soft);
  font-weight: 700;
}

.story-concern > span {
  color: var(--gold);
  background: var(--gold-soft);
}

.story-choice {
  margin-top: 15px;
  padding: 17px;
  border: 1px solid var(--green);
  border-radius: 16px;
  background: var(--green-soft);
}

.story-choice strong {
  display: block;
  margin-top: 6px;
}

.story-label {
  color: var(--green);
  font-weight: 700;
}

.language-translation {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 12px;
  align-items: start;
  margin-top: 14px;
  padding: 13px 15px;
  border-left: 4px solid var(--blue);
  border-radius: 8px;
  background: var(--blue-soft);
}

.language-translation > span {
  color: var(--blue);
  font-weight: 700;
}

.language-translation p {
  margin: 0;
}

.compact-translation {
  margin-top: 16px;
}


.opposite-sides,
.direction-lessons {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 16px;
  align-items: stretch;
  margin-top: 24px;
}

.direction-lessons {
  grid-template-columns: 1fr 1fr;
}

.side-explanation,
.direction-lesson,
.contract-anatomy article,
.lifecycle-flow article {
  padding: 18px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--surface);
  text-align: center;
}

.holder-side {
  border-color: var(--blue);
}

.seller-side,
.cash-obligation {
  border-color: var(--green) !important;
}

.side-symbol {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  margin: 0 auto 10px;
  border-radius: 14px;
  color: var(--blue);
  background: var(--blue-soft);
  font-weight: 700;
}

.seller-side .side-symbol {
  color: var(--green);
  background: var(--green-soft);
}

.side-label,
.direction-name,
.anatomy-label {
  display: block;
  margin-bottom: 6px;
  color: var(--muted);
}

.side-explanation strong,
.direction-lesson strong,
.contract-anatomy strong,
.lifecycle-flow strong {
  display: block;
}

.side-explanation p,
.direction-lesson p,
.contract-anatomy p,
.lifecycle-flow p {
  margin: 8px 0 0;
  color: var(--muted);
}

.contract-link {
  align-self: center;
  padding: 7px 9px;
  border-radius: 999px;
  color: var(--gold);
  background: var(--gold-soft);
  white-space: nowrap;
}

.direction-name {
  color: var(--blue);
  font-weight: 700;
  letter-spacing: 0.08em;
}

.two-way-transfer {
  display: grid;
  gap: 8px;
  margin-top: 16px;
  padding: 12px;
  border-radius: 13px;
  background: var(--blue-soft);
}

.two-way-transfer div {
  padding: 7px 9px;
  border-radius: 9px;
  color: var(--blue);
  background: var(--surface);
  text-align: left;
}

.market-line {
  padding-top: 10px;
  border-top: 1px solid var(--border);
}

.foundation-takeaway {
  margin: 18px auto 0;
  color: var(--text);
  text-align: center;
  font-weight: 700;
}

.contract-anatomy {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr;
  gap: 10px;
  align-items: center;
  margin-top: 24px;
}

.contract-anatomy article {
  height: 100%;
}

.math-symbol {
  color: var(--muted);
  font-size: 1.4rem;
}

.premium-line {
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
  margin: 16px auto 0;
  padding: 12px;
  border-radius: 13px;
  color: var(--green);
  background: var(--green-soft);
}

.collateral-line {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 8px 12px;
  margin-top: 12px;
  padding: 12px 14px;
  border-left: 4px solid var(--gold);
  border-radius: 8px;
  background: var(--gold-soft);
}

.collateral-line strong {
  color: var(--gold);
}

.lifecycle-flow {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr;
  gap: 10px;
  align-items: center;
  margin-top: 24px;
}

.lifecycle-flow article > span {
  display: grid;
  place-items: center;
  width: 32px;
  height: 32px;
  margin: 0 auto 9px;
  border-radius: 50%;
  color: var(--blue);
  background: var(--blue-soft);
  font-weight: 700;
}

.lifecycle-flow .clearing-step {
  border-color: var(--gold);
}

.expiration-note {
  display: grid;
  gap: 5px;
  margin-top: 16px;
  padding: 13px 15px;
  border-left: 4px solid var(--gold);
  border-radius: 8px;
  background: var(--gold-soft);
}

.term-list {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 7px 11px;
  flex-wrap: wrap;
  margin-top: 18px;
  color: var(--muted);
}

.term-list button {
  margin: 0;
  padding: 2px 0;
  border: 0;
  border-bottom: 1px dotted var(--blue);
  color: var(--blue);
  background: transparent;
  cursor: help;
}

.term-list button:hover,
.term-list button:focus-visible {
  color: var(--text);
  border-bottom-style: solid;
}

.intro-mechanism {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr;
  align-items: center;
  gap: 10px;
  max-width: 820px;
  margin: 34px auto 0;
}

.mechanism-card {
  min-height: 102px;
  padding: 15px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--surface);
  text-align: center;
}

.clearing-card {
  border-color: var(--gold);
}

.mechanism-label {
  display: block;
  margin-bottom: 7px;
  color: var(--muted);
}

.mechanism-arrow {
  color: var(--muted);
  font-size: 1.4rem;
}

.route {
  position: relative;
  height: 102px;
  max-width: 760px;
  margin: 22px auto 0;
}

.route::before {
  content: "";
  position: absolute;
  left: 4%;
  right: 4%;
  top: 58px;
  height: 3px;
  border-radius: 3px;
  background: var(--border);
}

.route-stop {
  position: absolute;
  top: 49px;
  width: 20px;
  height: 20px;
  border: 3px solid var(--border);
  border-radius: 50%;
  background: var(--surface);
  transform: translateX(-50%);
}

.route-left {
  left: 5%;
}

.route-center {
  left: 50%;
  border-color: var(--gold);
}

.route-right {
  left: 95%;
}

.asset-token {
  position: absolute;
  z-index: 2;
  top: 2px;
  left: 50%;
  padding: 10px 14px;
  border-radius: 999px;
  font-weight: 700;
  white-space: nowrap;
  transform: translateX(-50%);
}

.cash-token {
  color: var(--green);
  background: var(--green-soft);
}

.shares-token {
  color: var(--blue);
  background: var(--blue-soft);
}

.asset-token.routing-left {
  animation: route-left 1.65s ease-in-out forwards;
}

.asset-token.routing-right {
  animation: route-right 1.65s ease-in-out forwards;
}

@keyframes route-left {
  0% {
    top: 38px;
    left: 95%;
    opacity: 0;
  }
  8% {
    opacity: 1;
  }
  50% {
    top: 38px;
    left: 50%;
  }
  100% {
    top: 38px;
    left: 5%;
    opacity: 1;
  }
}

@keyframes route-right {
  0% {
    top: 38px;
    left: 5%;
    opacity: 0;
  }
  8% {
    opacity: 1;
  }
  50% {
    top: 38px;
    left: 50%;
  }
  100% {
    top: 38px;
    left: 95%;
    opacity: 1;
  }
}

.feedback {
  min-height: 48px;
  max-width: 680px;
  margin: 10px auto 0;
  color: var(--muted);
  text-align: center;
}

.feedback.correct {
  color: var(--green);
}

.feedback.incorrect {
  color: var(--red);
}

.intro-feedback {
  margin-top: 22px;
}

.choices {
  display: flex;
  justify-content: center;
  gap: 10px;
  flex-wrap: wrap;
}

.choices button,
.secondary-action,
.primary-action {
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 11px 15px;
  color: var(--text);
  background: var(--surface);
  cursor: pointer;
}

.choices button:hover:not(:disabled) {
  border-color: var(--blue);
}

.choices button:disabled,
.primary-action:disabled {
  opacity: 0.48;
  cursor: default;
}

.account-review {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  max-width: 720px;
  margin: 20px auto 0;
}

.account-card {
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: 15px;
  background: var(--surface);
}

.operator-account {
  border-color: var(--green);
}

.account-card h3 {
  margin: 0 0 10px;
  font-size: 1rem;
}

.account-card div,
.result-bridge {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 7px 14px;
}

.account-card div {
  margin-top: 6px;
  color: var(--muted);
}

.account-card strong {
  color: var(--text);
}

.result-bridge {
  max-width: 480px;
  margin: 18px auto 0;
  padding: 14px;
  border-radius: 14px;
  background: var(--soft);
}

.result-total {
  padding-top: 8px;
  border-top: 1px solid var(--border);
  font-weight: 700;
}

.loss {
  color: var(--red);
}

.lesson-footer {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 17px;
}

.term-reminder {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 8px 13px;
  align-items: baseline;
  margin-top: 14px;
  padding: 11px 14px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--soft);
}

.term-reminder-label {
  color: var(--blue);
  font-weight: 700;
}

.term-reminder p {
  margin: 0;
  color: var(--muted);
}

.secondary-action {
  color: var(--muted);
}

.primary-action {
  border-color: var(--blue);
  color: #ffffff;
  background: var(--blue);
  font-weight: 700;
}

.lesson-boundary {
  margin: 16px 0 0;
  color: var(--muted);
  text-align: center;
  font-size: 0.9rem;
}

@media (max-width: 700px) {
  body {
    padding: 8px;
  }

  .lesson {
    border-radius: 15px;
  }

  .mode-label {
    display: none;
  }

  .perspective-bridge,
  .ticket-body {
    grid-template-columns: 1fr;
  }

  .ticket-header {
    align-items: flex-start;
  }

  .ticket-status {
    white-space: normal;
    text-align: center;
  }

  .plain-contract {
    border-top: 1px solid var(--border);
    border-left: 0;
  }

  .platform-contract dl {
    grid-template-columns: 1fr;
  }

  .roles {
    grid-template-columns: 1fr 90px 1fr;
    gap: 8px;
  }

  .role-icon,
  .clearing-icon {
    width: 62px;
    height: 62px;
    border-radius: 20px;
  }

  .role span,
  .clearing-role span {
    display: none;
  }

  .intro-mechanism {
    grid-template-columns: 1fr;
    margin-top: 18px;
  }

  .opposite-sides,
  .direction-lessons,
  .contract-anatomy,
  .lifecycle-flow,
  .story-start {
    grid-template-columns: 1fr;
  }

  .language-translation {
    grid-template-columns: 1fr;
  }

  .collateral-line {
    grid-template-columns: 1fr;
  }

  .lifecycle-flow > div[aria-hidden="true"] {
    transform: rotate(90deg);
    justify-self: center;
  }

  .term-reminder {
    grid-template-columns: 1fr;
  }

  .mechanism-arrow {
    transform: rotate(90deg);
    text-align: center;
  }

  .interaction {
    min-height: 570px;
  }

  .account-review {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  .asset-token.routing-left {
    animation: none;
    top: 38px;
    left: 5%;
  }

  .asset-token.routing-right {
    animation: none;
    top: 38px;
    left: 95%;
  }

  .progress-track span {
    transition: none;
  }
}