/* ===== reset / base ===== */
* { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --primary: #1976ff;
  --primary-dark: #0c5fbf;
  --primary-light: #e8f1ff;
  --accent: #ffb547;
  --green: #18b86b;
  --text: #1a2233;
  --text-2: #5a6478;
  --text-3: #8a93a6;
  --bg: #f5f8fc;
  --bg-alt: #ffffff;
  --bg-dark: #0f1a36;
  --border: #e3e9f2;
  --shadow: 0 8px 24px rgba(20, 50, 120, 0.08);
  --shadow-lg: 0 18px 50px rgba(20, 50, 120, 0.15);
  --radius: 14px;
  --radius-sm: 10px;
}
html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei",
               "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }
input { font-family: inherit; }
ul { list-style: none; }
.container { max-width: 1180px; margin: 0 auto; padding: 0 20px; }

/* ===== demo banner ===== */
.demo-banner {
  background: linear-gradient(90deg, #ffeacc, #fff5e0);
  color: #7a4500;
  padding: 10px 50px 10px 20px;
  font-size: 13px;
  text-align: center;
  position: relative;
  border-bottom: 1px solid #ffd599;
}
.demo-banner b { color: #b13b00; }
.demo-close {
  position: absolute; right: 12px; top: 50%; transform: translateY(-50%);
  width: 26px; height: 26px; border-radius: 50%;
  background: rgba(0,0,0,0.06); color: #7a4500; font-size: 18px; line-height: 1;
}
.demo-close:hover { background: rgba(0,0,0,0.12); }

/* ===== navbar ===== */
.navbar {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,0.92);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 64px;
}
.logo { display: flex; align-items: center; gap: 8px; font-weight: 700; font-size: 20px; }
.logo-icon {
  display: inline-flex; align-items: center; justify-content: center;
  width: 34px; height: 34px; border-radius: 10px;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff; font-size: 18px;
}
.logo-text b { color: var(--primary); }
.logo-text.light { color: #fff; }
.logo-text.light b { color: var(--accent); }

.nav-menu { display: flex; gap: 4px; }
.nav-link {
  padding: 8px 14px; border-radius: 8px;
  font-size: 14px; color: var(--text-2);
  transition: all .2s;
}
.nav-link:hover { color: var(--primary); background: var(--primary-light); }
.nav-link.active { color: var(--primary); background: var(--primary-light); font-weight: 600; }
.nav-toggle { display: none; font-size: 24px; color: var(--text); }

/* ===== hero ===== */
.hero {
  background: radial-gradient(circle at 20% 0%, #dde9ff 0%, transparent 50%),
              radial-gradient(circle at 100% 100%, #fff0d6 0%, transparent 50%),
              linear-gradient(180deg, #f5f8fc 0%, #ffffff 100%);
  padding: 80px 0 60px;
  text-align: center;
}
.hero-tag {
  display: inline-block; padding: 6px 16px;
  background: rgba(25, 118, 255, 0.1); color: var(--primary);
  border-radius: 50px; font-size: 13px; font-weight: 600;
  margin-bottom: 24px;
}
.hero-title {
  font-size: clamp(36px, 5vw, 56px);
  font-weight: 800; letter-spacing: -1px;
  margin-bottom: 16px;
}
.hero-title .grad {
  background: linear-gradient(135deg, var(--primary), var(--green));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-sub { font-size: 18px; color: var(--text-2); margin-bottom: 28px; }
.hero-sub b { color: var(--primary); }
.hero-notice {
  display: inline-block; max-width: 760px;
  background: linear-gradient(90deg, #fff8eb, #fffaf0);
  border: 1px solid #ffe2a8;
  color: #7a4500;
  padding: 14px 22px; border-radius: 12px;
  font-size: 14px; line-height: 1.7;
  margin-bottom: 36px;
}
.hero-notice b { color: #b13b00; }
.hero-cta { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; margin-bottom: 56px; }

.btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 13px 28px; border-radius: 50px;
  font-size: 15px; font-weight: 600;
  transition: all .2s;
}
.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff; box-shadow: 0 6px 16px rgba(25,118,255,0.35);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 10px 24px rgba(25,118,255,0.45); }
.btn-ghost {
  background: #fff; color: var(--primary); border: 1px solid var(--border);
}
.btn-ghost:hover { border-color: var(--primary); background: var(--primary-light); }
.btn-lg { padding: 16px 36px; font-size: 16px; }
.btn-sm { padding: 6px 14px; font-size: 13px; }

.hero-stats {
  display: grid; grid-template-columns: repeat(4, 1fr);
  gap: 16px; max-width: 760px; margin: 0 auto;
}
.stat {
  background: #fff; border-radius: var(--radius);
  padding: 22px 12px;
  box-shadow: var(--shadow);
}
.stat b {
  display: block; font-size: 28px; font-weight: 800;
  color: var(--primary); margin-bottom: 4px;
}
.stat span { font-size: 13px; color: var(--text-3); }

/* ===== flow ===== */
.flow { padding: 60px 0; background: #fff; }
.section-title {
  font-size: 30px; font-weight: 800; text-align: center;
  margin-bottom: 12px;
}
.section-title.light { color: #fff; }
.section-sub {
  text-align: center; color: var(--text-2);
  font-size: 15px; margin-bottom: 36px;
}
.section-sub.light { color: rgba(255,255,255,0.75); }
.section-sub b { color: var(--primary); }

.flow-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px;
}
.flow-item {
  background: var(--bg);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
  position: relative;
  transition: transform .2s;
}
.flow-item:hover { transform: translateY(-4px); }
.flow-num {
  width: 44px; height: 44px; border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff; font-weight: 800; font-size: 18px;
  display: flex; align-items: center; justify-content: center;
  margin: 0 auto 14px;
}
.flow-text { font-size: 14px; color: var(--text-2); }

/* ===== panel sections ===== */
.panel { padding: 70px 0; }
.panel-alt { background: #fff; }
.panel-dark { background: linear-gradient(135deg, #0f1a36 0%, #1c2c5a 100%); color: #fff; }

/* ===== card grid ===== */
.card-grid { display: grid; gap: 18px; margin-bottom: 32px; }
.card-grid.two { grid-template-columns: repeat(2, 1fr); }
.card-grid.three { grid-template-columns: repeat(3, 1fr); }
.card {
  background: #fff; border: 1px solid var(--border);
  border-radius: var(--radius); padding: 26px;
  transition: all .2s;
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); border-color: var(--primary); }
.card-head { display: flex; align-items: center; gap: 10px; margin-bottom: 12px; flex-wrap: wrap; }
.card-tag {
  font-size: 12px; padding: 3px 10px; border-radius: 50px; font-weight: 600;
}
.card-tag.green { background: #e3f9ed; color: var(--green); }
.card-tag.blue { background: var(--primary-light); color: var(--primary); }
.card h3 { font-size: 18px; font-weight: 700; }
.card-price {
  font-size: 36px; font-weight: 800; color: var(--primary);
  margin: 8px 0;
}
.card-price small { font-size: 16px; color: var(--text-3); font-weight: 600; }
.card-desc { font-size: 14px; color: var(--text-2); }
.card-icon { font-size: 38px; margin-bottom: 12px; }
.card-dark {
  background: rgba(255,255,255,0.05);
  border-color: rgba(255,255,255,0.12);
  color: #fff;
}
.card-dark p { color: rgba(255,255,255,0.7); font-size: 14px; }
.card-dark:hover { background: rgba(255,255,255,0.08); border-color: var(--accent); }

.service-card { text-align: center; }
.service-card .mono { margin: 8px 0 16px; }

/* ===== form ===== */
.form-card {
  background: #fff; border: 1px solid var(--border);
  border-radius: var(--radius); padding: 30px;
  box-shadow: var(--shadow);
}
.form-label {
  display: block; font-size: 14px; font-weight: 600;
  margin: 18px 0 10px; color: var(--text);
}
.form-label:first-child { margin-top: 0; }
.form-tip {
  padding: 12px 16px;
  background: var(--primary-light);
  border-radius: var(--radius-sm);
  font-size: 13.5px;
  color: var(--primary-dark);
  margin-bottom: 6px;
}
.form-tip b { color: var(--primary); }
.form-input {
  width: 100%; padding: 13px 16px;
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  font-size: 15px; background: var(--bg);
  transition: all .15s;
}
.form-input:focus { outline: none; border-color: var(--primary); background: #fff; box-shadow: 0 0 0 3px rgba(25,118,255,0.12); }
.form-input.readonly { background: #f0f4fa; color: var(--text-2); cursor: not-allowed; }

.pill-group { display: flex; flex-wrap: wrap; gap: 10px; }
.pill {
  padding: 9px 18px; border: 1px solid var(--border);
  border-radius: 50px; background: #fff;
  font-size: 14px; font-weight: 500; color: var(--text-2);
  transition: all .15s;
}
.pill:hover { border-color: var(--primary); color: var(--primary); }
.pill.active {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff; border-color: transparent;
  box-shadow: 0 4px 12px rgba(25,118,255,0.3);
}
.pill-custom {
  background: var(--primary-light); color: var(--primary);
  border-color: transparent;
}
.pill-custom.active { background: linear-gradient(135deg, var(--accent), #ff8a47); color: #fff; }

/* ===== pay box ===== */
.pay-box {
  margin-top: 26px; padding: 22px;
  background: var(--bg); border-radius: var(--radius-sm);
  border: 1px dashed var(--border);
}
.pay-row {
  display: flex; justify-content: space-between; align-items: center;
  padding: 10px 0; border-bottom: 1px dashed var(--border);
  gap: 12px; flex-wrap: wrap;
}
.pay-row:last-of-type { border-bottom: none; }
.pay-key { font-size: 14px; color: var(--text-2); }
.pay-val { font-size: 15px; font-weight: 600; color: var(--text); text-align: right; }
.pay-val[data-pay] { font-size: 20px; color: var(--primary); }
.mono { font-family: "SF Mono", Menlo, Consolas, monospace; font-size: 13px; word-break: break-all; }
.addr { color: var(--text-2); }
.copy-btn {
  padding: 5px 12px; border-radius: 6px; background: var(--primary); color: #fff;
  font-size: 12px; margin-left: 8px; font-weight: 600;
}
.copy-btn:hover { background: var(--primary-dark); }
.pay-qr { display: flex; align-items: center; gap: 18px; margin-top: 16px; padding-top: 16px; border-top: 1px dashed var(--border); }
.qr-placeholder {
  width: 100px; height: 100px; flex-shrink: 0;
  background: #fff; border: 2px dashed var(--border);
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 13px; color: var(--text-3); text-align: center; line-height: 1.3;
}
.qr-img {
  width: 90px; height: 90px; flex-shrink: 0;
  background: #fff; border: 1px solid var(--border);
  border-radius: 8px; padding: 4px;
  object-fit: contain;
}
.pay-tip { font-size: 13px; color: var(--text-2); }

/* ===== features ===== */
.feature-list { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; max-width: 760px; margin: 0 auto 30px; }
.feature { background: var(--bg); padding: 14px 18px; border-radius: var(--radius-sm); font-size: 14px; }

/* ===== exchange ===== */
.rate-bar {
  display: grid; grid-template-columns: repeat(4, 1fr);
  gap: 14px; margin-bottom: 28px;
}
.rate-item {
  background: linear-gradient(135deg, #f0f6ff, #fff);
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  padding: 14px; text-align: center;
}
.rate-item span { display: block; font-size: 12px; color: var(--text-3); margin-bottom: 4px; }
.rate-item b { font-size: 16px; color: var(--primary); }

.exchange-row { display: grid; grid-template-columns: 1fr auto 1fr; gap: 16px; align-items: end; margin-bottom: 18px; }
.exchange-arrow { font-size: 30px; color: var(--primary); padding-bottom: 14px; }
.exchange-input { position: relative; }
.exchange-input .suffix {
  position: absolute; right: 16px; top: 50%; transform: translateY(-50%);
  font-size: 14px; font-weight: 600; color: var(--text-3);
}
.exchange-input input { padding-right: 60px; }
.hint { font-size: 12px; color: var(--text-3); margin-top: 6px; }

/* ===== about ===== */
.about-text {
  max-width: 820px; margin: 0 auto 36px;
  font-size: 16px; line-height: 1.9; color: var(--text-2); text-align: center;
}
.about-text b { color: var(--primary); }
.tag-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; max-width: 900px; margin: 0 auto; }
.tag-item {
  background: linear-gradient(135deg, #fff, #f0f6ff);
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  padding: 18px; text-align: center;
  font-size: 14px; font-weight: 600; color: var(--text);
  transition: all .2s;
}
.tag-item:hover { border-color: var(--primary); transform: translateY(-3px); }

.cta-center { text-align: center; margin-top: 30px; }

/* ===== footer ===== */
.footer {
  background: var(--bg-dark); color: rgba(255,255,255,0.7);
  padding: 50px 0 24px; margin-top: 40px;
}
.footer-top { display: grid; grid-template-columns: 1.5fr 1fr 1fr; gap: 40px; padding-bottom: 30px; border-bottom: 1px solid rgba(255,255,255,0.08); }
.footer-brand p { margin-top: 14px; font-size: 14px; line-height: 1.7; }
.footer-col h4 { color: #fff; font-size: 16px; margin-bottom: 14px; }
.footer-col li { padding: 4px 0; font-size: 14px; }
.footer-col a:hover { color: var(--accent); }
.footer-bottom {
  margin-top: 22px; display: flex; justify-content: space-between;
  font-size: 13px; color: rgba(255,255,255,0.4); flex-wrap: wrap; gap: 10px;
}
.footer-demo { color: var(--accent); }

/* ===== toast ===== */
.toast {
  position: fixed; bottom: 40px; left: 50%; transform: translateX(-50%) translateY(20px);
  background: rgba(15,26,54,0.95); color: #fff;
  padding: 12px 24px; border-radius: 50px; font-size: 14px;
  opacity: 0; pointer-events: none; transition: all .25s;
  z-index: 200;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ===== responsive ===== */
@media (max-width: 900px) {
  .nav-menu {
    position: absolute; top: 64px; left: 0; right: 0;
    flex-direction: column; gap: 0;
    background: #fff; border-bottom: 1px solid var(--border);
    padding: 10px 20px; display: none;
  }
  .nav-menu.open { display: flex; }
  .nav-link { padding: 12px 14px; border-radius: 8px; }
  .nav-toggle { display: block; }
  .hero-stats, .flow-grid, .feature-list, .tag-grid,
  .card-grid.two, .card-grid.three, .rate-bar, .footer-top {
    grid-template-columns: repeat(2, 1fr);
  }
  .exchange-row { grid-template-columns: 1fr; }
  .exchange-arrow { transform: rotate(90deg); padding: 0; }
}
@media (max-width: 560px) {
  .hero { padding: 50px 0 40px; }
  .hero-stats, .flow-grid, .feature-list, .tag-grid,
  .card-grid.two, .card-grid.three, .rate-bar, .footer-top {
    grid-template-columns: 1fr;
  }
  .section-title { font-size: 24px; }
  .pay-qr { flex-direction: column; align-items: flex-start; }
}