:root {
  --ink: #121916;
  --muted: #617069;
  --line: #dfe7e2;
  --soft: #f3f7f4;
  --paper: #ffffff;
  --green: #0f8a5f;
  --green-dark: #086143;
  --mint: #dff5e9;
  --coral: #ef634d;
  --amber: #fff3d5;
  --shadow: 0 16px 40px rgba(18, 25, 22, .08);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: #f8faf8;
  font-family: Inter, "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.65;
}
button, input { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; text-decoration: none; }

.site-header {
  height: 72px;
  padding: 0 max(24px, calc((100vw - 1180px) / 2));
  display: flex;
  align-items: center;
  gap: 38px;
  background: rgba(255,255,255,.94);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(12px);
}
.brand { display: inline-flex; align-items: center; gap: 10px; flex: none; }
.brand-mark {
  width: 38px;
  height: 38px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: var(--ink);
  color: white;
  font: 800 20px/1 Arial, sans-serif;
}
.brand strong, .brand small { display: block; letter-spacing: 0; }
.brand strong { font-size: 17px; line-height: 1.15; }
.brand small { margin-top: 2px; color: var(--muted); font-size: 9px; }
nav { display: flex; gap: 28px; margin-right: auto; }
nav a { color: #425049; font-size: 14px; }
nav a:hover { color: var(--green-dark); }
.support-link {
  height: 38px;
  padding: 0 17px;
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--ink);
  border-radius: 6px;
  font-size: 14px;
  font-weight: 700;
}
.support-link:hover { background: var(--ink); color: white; }
.bot-link {
  height: 38px;
  padding: 0 17px;
  display: inline-flex;
  align-items: center;
  border-radius: 6px;
  background: var(--green);
  color: white;
  font-size: 14px;
  font-weight: 800;
}
.bot-link:hover { background: var(--green-dark); }

main { overflow: hidden; }
.intro-band,
.order-shell,
.flow-band,
.content-band,
.faq-band,
footer {
  width: min(1180px, calc(100% - 48px));
  margin-inline: auto;
}
.intro-band {
  min-height: 252px;
  padding: 54px 0 38px;
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: 50px;
}
.eyebrow, .step-label {
  margin: 0 0 8px;
  color: var(--green);
  font-size: 12px;
  font-weight: 800;
}
h1, h2, h3, p { letter-spacing: 0; }
h1 { margin: 0; font-size: clamp(38px, 5vw, 64px); line-height: 1.12; }
.intro-copy { max-width: 700px; margin: 18px 0 0; color: var(--muted); font-size: 17px; }
.intro-actions { margin-top: 22px; display: flex; align-items: center; gap: 18px; }
.primary-bot { min-height: 48px; padding: 8px 16px; display: inline-flex; align-items: center; gap: 12px; border-radius: 6px; background: var(--ink); color: white; }
.primary-bot strong, .primary-bot span { display: block; }
.primary-bot strong { font-size: 14px; }
.primary-bot span { color: #9fc9b5; font-size: 11px; }
.primary-bot:hover { background: var(--green-dark); }
.text-action { color: var(--green-dark); font-size: 13px; font-weight: 700; text-decoration: underline; text-underline-offset: 4px; }
.price-signal {
  min-width: 220px;
  padding-left: 25px;
  border-left: 3px solid var(--coral);
}
.price-signal span, .price-signal em { display: block; color: var(--muted); font-size: 13px; font-style: normal; }
.price-signal strong { display: block; margin: 2px 0; color: var(--green-dark); font-size: 40px; line-height: 1.15; }
.price-signal small { font-size: 14px; }

.order-shell {
  display: grid;
  grid-template-columns: minmax(0, .88fr) minmax(0, 1.12fr);
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: var(--shadow);
}
.order-panel, .payment-panel { min-width: 0; padding: 30px; }
.order-panel { border-right: 1px solid var(--line); }
.section-heading { display: flex; align-items: flex-start; justify-content: space-between; gap: 20px; }
.section-heading h2 { margin: 0; font-size: 23px; line-height: 1.3; }
.arrival-badge {
  padding: 5px 10px;
  border-radius: 4px;
  background: var(--mint);
  color: var(--green-dark);
  font-size: 12px;
  font-weight: 800;
}
.chain-link { color: var(--green-dark); font-size: 13px; text-decoration: underline; text-underline-offset: 4px; }

.quantity-control {
  height: 92px;
  margin-top: 28px;
  display: grid;
  grid-template-columns: 58px 1fr 58px;
  align-items: stretch;
  border: 1px solid var(--line);
  border-radius: 7px;
  overflow: hidden;
}
.icon-button {
  border: 0;
  background: var(--soft);
  color: var(--ink);
  cursor: pointer;
  font-size: 28px;
}
.icon-button:hover { background: var(--mint); }
.quantity-value { display: flex; align-items: baseline; justify-content: center; gap: 8px; }
.quantity-value strong { font-size: 42px; line-height: 1; }
.quantity-value span { color: var(--muted); }
.preset-row { margin-top: 10px; display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; }
.preset-row button {
  height: 38px;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: white;
  cursor: pointer;
  font-weight: 700;
}
.preset-row button:hover, .preset-row button.active { border-color: var(--ink); background: var(--ink); color: white; }

.order-summary { margin-top: 24px; border-top: 1px solid var(--line); }
.order-summary div { min-height: 52px; display: flex; align-items: center; justify-content: space-between; gap: 18px; border-bottom: 1px solid var(--line); }
.order-summary span { color: var(--muted); font-size: 14px; }
.order-summary strong { text-align: right; }
.order-summary b { color: var(--green-dark); font-size: 23px; }
.payer-notice { margin-top: 22px; padding: 15px 17px; background: var(--mint); border-left: 3px solid var(--green); }
.payer-notice strong { font-size: 14px; }
.payer-notice p { margin: 3px 0 0; color: #355448; font-size: 13px; }

.payment-body { margin-top: 28px; display: grid; grid-template-columns: 176px minmax(0, 1fr); gap: 22px; align-items: center; }
.qr-code {
  width: 176px;
  height: 176px;
  padding: 10px;
  display: grid;
  place-items: center;
  background: white;
  border: 1px solid var(--line);
  border-radius: 6px;
}
.qr-code img, .qr-code canvas { width: 154px !important; height: 154px !important; display: block; }
.payment-details { min-width: 0; }
.field-label { display: block; margin: 0 0 6px; color: var(--muted); font-size: 12px; }
.address-box, .amount-box {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--soft);
  cursor: pointer;
  text-align: left;
}
.address-box { min-height: 68px; padding: 11px 13px; display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.address-box code { min-width: 0; overflow-wrap: anywhere; color: var(--ink); font-size: 13px; }
.address-box span, .amount-box span { flex: none; color: var(--green-dark); font-size: 12px; font-weight: 800; }
.amount-box { min-height: 62px; margin-top: 0; padding: 9px 13px; display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.amount-box strong { font-size: 23px; }
.payment-details .field-label:nth-of-type(2) { margin-top: 14px; }
.address-book-tip { margin-top: 22px; padding: 14px 16px; border: 1px dashed #9fc9b5; border-radius: 6px; background: #f4fbf7; }
.address-book-tip strong { color: var(--green-dark); font-size: 14px; }
.address-book-tip p { margin: 3px 0 0; color: #496057; font-size: 13px; }
.exact-warning { margin-top: 25px; padding: 14px 16px; background: var(--amber); border: 1px solid #f2d985; border-radius: 6px; }
.exact-warning strong { font-size: 14px; }
.exact-warning p { margin: 3px 0 0; color: #745e20; font-size: 13px; }

.flow-band { padding: 82px 0; display: grid; grid-template-columns: .58fr 1.42fr; gap: 70px; align-items: start; }
.flow-heading h2, .content-main h2, .faq-band h2 { margin: 0; font-size: 34px; line-height: 1.25; }
.flow-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 0; }
.flow-list li { min-height: 96px; padding: 20px 0; display: grid; grid-template-columns: 50px 1fr; gap: 18px; border-bottom: 1px solid var(--line); }
.flow-list li:first-child { border-top: 1px solid var(--line); }
.flow-list > li > span { color: var(--coral); font-weight: 800; }
.flow-list strong { font-size: 18px; }
.flow-list p { margin: 3px 0 0; color: var(--muted); font-size: 14px; }

.exchange-band {
  width: 100%;
  margin-top: 76px;
  padding: 72px max(24px, calc((100vw - 1180px) / 2)) 0;
  background: #e9f2ed;
  border-top: 1px solid #d2e1d9;
  border-bottom: 1px solid #d2e1d9;
}
.exchange-inner {
  display: grid;
  grid-template-columns: .82fr 1.18fr;
  gap: 86px;
  align-items: center;
}
.exchange-copy h2 { margin: 0; font-size: 38px; line-height: 1.2; }
.exchange-copy > p:not(.eyebrow) { max-width: 470px; color: #53665c; }
.rate-line { margin-top: 28px; padding-left: 18px; border-left: 3px solid var(--coral); }
.rate-line span, .rate-line em { display: block; color: var(--muted); font-size: 12px; font-style: normal; }
.rate-line strong { display: block; margin: 2px 0; font-size: 25px; }
.rate-line strong.error { color: #a94232; }
.exchange-tool { padding: 30px; background: white; border: 1px solid #d2e1d9; border-radius: 8px; box-shadow: 0 12px 34px rgba(18,25,22,.07); }
.exchange-tool > label { display: block; margin-bottom: 7px; color: var(--muted); font-size: 13px; }
.currency-input {
  height: 72px;
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--soft);
  overflow: hidden;
}
.currency-input input {
  width: 100%;
  height: 100%;
  min-width: 0;
  padding: 0 18px;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--ink);
  font-size: 30px;
  font-weight: 800;
}
.currency-input input:focus { box-shadow: inset 0 0 0 2px var(--green); }
.currency-input strong { padding: 0 18px; color: var(--green-dark); font-size: 14px; }
.swap-presets { margin-top: 8px; display: grid; grid-template-columns: repeat(4, 1fr); gap: 7px; }
.swap-presets button { height: 36px; border: 1px solid var(--line); border-radius: 5px; background: white; cursor: pointer; font-weight: 700; }
.swap-presets button:hover, .swap-presets button.active { border-color: var(--ink); background: var(--ink); color: white; }
.swap-output { min-height: 72px; margin-top: 20px; padding: 0 2px; display: flex; align-items: center; justify-content: space-between; gap: 18px; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.swap-output span { color: var(--muted); font-size: 14px; }
.swap-output strong { text-align: right; font-size: 18px; }
.swap-output b { color: var(--green-dark); font-size: 28px; }
.swap-range { margin: 10px 0 16px; color: var(--muted); font-size: 12px; }
.exchange-address { width: 100%; padding: 13px 15px; display: grid; grid-template-columns: 1fr auto; gap: 2px 12px; border: 0; border-radius: 6px; background: var(--ink); color: white; text-align: left; cursor: pointer; }
.exchange-address span { grid-column: 1; color: #aab9b1; font-size: 11px; }
.exchange-address code { grid-column: 1; min-width: 0; overflow-wrap: anywhere; color: white; font-size: 12px; }
.exchange-address b { grid-column: 2; grid-row: 1 / span 2; align-self: center; color: #54d79f; font-size: 12px; }
.exchange-rules { margin-top: 54px; min-height: 62px; display: grid; grid-template-columns: repeat(4, 1fr); border-top: 1px solid #c8dad0; }
.exchange-rules span { padding: 19px 18px; border-right: 1px solid #c8dad0; color: #496057; font-size: 12px; text-align: center; }
.exchange-rules span:last-child { border-right: 0; }

.content-band {
  width: 100%;
  padding: 76px max(24px, calc((100vw - 1180px) / 2));
  display: grid;
  grid-template-columns: 1.25fr .75fr;
  gap: 90px;
  background: var(--ink);
  color: white;
}
.content-main p:not(.eyebrow) { max-width: 720px; color: #c8d3cd; }
.safety-list { padding-top: 7px; }
.safety-list h3 { margin: 0 0 15px; font-size: 16px; }
.safety-list ul { list-style: none; padding: 0; margin: 0; }
.safety-list li { padding: 12px 0 12px 26px; position: relative; border-bottom: 1px solid #334139; color: #dce6e1; font-size: 14px; }
.safety-list li::before { content: "✓"; position: absolute; left: 0; color: #54d79f; font-weight: 800; }

.faq-band { padding: 82px 0 94px; }
.faq-list { margin-top: 34px; border-top: 1px solid var(--line); }
.faq-list details { border-bottom: 1px solid var(--line); }
.faq-list summary { padding: 20px 44px 20px 0; cursor: pointer; font-weight: 700; position: relative; list-style: none; }
.faq-list summary::-webkit-details-marker { display: none; }
.faq-list summary::after { content: "+"; position: absolute; right: 10px; top: 16px; font-size: 24px; font-weight: 400; }
.faq-list details[open] summary::after { content: "−"; }
.faq-list details p { max-width: 800px; margin: -5px 0 20px; color: var(--muted); font-size: 14px; }

footer { min-height: 150px; padding: 32px 0; display: flex; align-items: center; gap: 30px; border-top: 1px solid var(--line); color: var(--muted); font-size: 13px; }
.footer-brand { margin-right: auto; color: var(--ink); }
footer a { color: var(--green-dark); font-weight: 700; }
.toast {
  min-width: 170px;
  padding: 11px 16px;
  position: fixed;
  left: 50%;
  bottom: 28px;
  z-index: 50;
  transform: translate(-50%, 20px);
  border-radius: 6px;
  background: var(--ink);
  color: white;
  text-align: center;
  font-size: 14px;
  opacity: 0;
  pointer-events: none;
  transition: .2s ease;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

@media (max-width: 880px) {
  .site-header { padding-inline: 20px; gap: 18px; }
  nav { display: none; }
  .bot-link { margin-left: auto; }
  .intro-band { min-height: 0; align-items: start; }
  .price-signal { min-width: 185px; }
  .order-shell { grid-template-columns: 1fr; }
  .order-panel { border-right: 0; border-bottom: 1px solid var(--line); }
  .flow-band { grid-template-columns: 1fr; gap: 28px; }
  .exchange-inner { grid-template-columns: 1fr; gap: 35px; }
  .content-band { grid-template-columns: 1fr; gap: 42px; }
}

@media (max-width: 600px) {
  .site-header { height: 64px; }
  .brand-mark { width: 34px; height: 34px; }
  .brand strong { font-size: 15px; }
  .support-link { height: 34px; padding-inline: 12px; font-size: 13px; }
  .bot-link { height: 34px; padding-inline: 12px; font-size: 13px; }
  .support-link { display: none; }
  .intro-band, .order-shell, .flow-band, .faq-band, footer { width: calc(100% - 28px); }
  .intro-band { padding: 38px 0 28px; display: block; }
  h1 { font-size: 39px; }
  .intro-copy { margin-top: 14px; font-size: 15px; }
  .intro-actions { align-items: flex-start; flex-direction: column; gap: 10px; }
  .price-signal { margin-top: 26px; padding: 12px 0 12px 18px; }
  .price-signal strong { font-size: 34px; }
  .order-panel, .payment-panel { padding: 22px 18px; }
  .section-heading h2 { font-size: 20px; }
  .quantity-control { height: 78px; grid-template-columns: 52px 1fr 52px; }
  .quantity-value strong { font-size: 36px; }
  .preset-row { gap: 5px; }
  .payment-body { grid-template-columns: 1fr; }
  .qr-code { width: 164px; height: 164px; margin: 0 auto; }
  .qr-code img, .qr-code canvas { width: 142px !important; height: 142px !important; }
  .address-box { display: block; }
  .address-box span { display: block; margin-top: 7px; }
  .flow-band { padding: 58px 0; }
  .exchange-band { margin-top: 52px; padding: 55px 14px 0; }
  .exchange-copy h2 { font-size: 30px; }
  .exchange-tool { padding: 20px 16px; }
  .currency-input { height: 66px; }
  .currency-input input { font-size: 27px; }
  .swap-output b { font-size: 24px; }
  .exchange-address { display: block; }
  .exchange-address code, .exchange-address b { display: block; margin-top: 5px; }
  .exchange-rules { grid-template-columns: 1fr 1fr; }
  .exchange-rules span:nth-child(2) { border-right: 0; }
  .exchange-rules span:nth-child(-n+2) { border-bottom: 1px solid #c8dad0; }
  .flow-heading h2, .content-main h2, .faq-band h2 { font-size: 28px; }
  .content-band { padding: 56px 20px; }
  .faq-band { padding: 60px 0 70px; }
  footer { min-height: 190px; flex-direction: column; align-items: flex-start; gap: 10px; }
  .footer-brand { margin: 0 0 8px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .toast { transition: none; }
}