:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --danger: #ef4444;
  --text: #172033;
  --muted: #667085;
  --line: #e5e7eb;
  --bg: #f6f8fb;
  --card: #ffffff;
  --soft: #eff6ff;
  --radius: 14px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
  line-height: 1.6;
}

.subflow {
  max-width: 940px;
  margin: 24px auto;
  padding: 0 16px 32px;
}

.hero {
  padding: 30px 24px;
  border-radius: var(--radius) var(--radius) 0 0;
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  color: #fff;
  text-align: center;
}

.hero h1 {
  margin: 0 0 8px;
  font-size: 30px;
  line-height: 1.25;
}

.hero p {
  margin: 0 auto;
  max-width: 720px;
  color: rgba(255, 255, 255, .9);
  font-size: 15px;
}

.card {
  padding: 24px;
  border: 1px solid var(--line);
  border-top: 0;
  border-radius: 0 0 var(--radius) var(--radius);
  background: var(--card);
  box-shadow: 0 14px 40px rgba(15, 23, 42, .08);
}

.intro-panel {
  display: grid;
  gap: 12px;
  margin-bottom: 18px;
  padding: 14px 16px;
  border: 1px solid #bfdbfe;
  border-radius: 12px;
  background: var(--soft);
}

.intro-main {
  display: flex;
  gap: 10px;
  align-items: baseline;
  flex-wrap: wrap;
  color: #1e3a8a;
  font-size: 14px;
}

.intro-main strong {
  font-size: 15px;
}

.protocol-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.protocol-chips span {
  padding: 3px 9px;
  border: 1px solid #dbeafe;
  border-radius: 999px;
  background: #fff;
  color: #475467;
  font-size: 12px;
}

.converter-flow {
  display: grid;
  gap: 14px;
}

.step-card,
.advanced-card {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
}

.step-head,
.advanced-summary {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  margin-bottom: 14px;
}

.step-index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  flex: 0 0 28px;
  border-radius: 999px;
  background: var(--primary);
  color: #fff;
  font-size: 14px;
  font-weight: 700;
}

.step-head h2,
.advanced-summary h2 {
  margin: 0;
  color: #172033;
  font-size: 17px;
  line-height: 1.4;
}

.step-head p,
.advanced-summary p {
  margin: 2px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.field-stack {
  display: grid;
  gap: 7px;
  margin-top: 12px;
}

.field-label,
.form-label {
  color: #344054;
  font-size: 14px;
  font-weight: 600;
}

.form-row {
  display: grid;
  grid-template-columns: 132px minmax(0, 1fr);
  gap: 14px;
  align-items: start;
  margin-bottom: 14px;
}

.form-label {
  padding-top: 9px;
}

input,
select,
textarea,
button {
  font: inherit;
}

textarea,
input[type="text"],
input[type="url"],
select {
  width: 100%;
  border: 1px solid #d0d5dd;
  border-radius: 9px;
  background: #fff;
  color: var(--text);
  outline: none;
  transition: border-color .18s ease, box-shadow .18s ease;
}

textarea {
  min-height: 118px;
  padding: 11px 12px;
  resize: vertical;
}

input[type="text"],
input[type="url"],
select {
  height: 42px;
  padding: 0 12px;
}

textarea:focus,
input[type="text"]:focus,
input[type="url"]:focus,
select:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, .13);
}

.help {
  margin-top: 7px;
  color: var(--muted);
  font-size: 13px;
}

.advanced-card {
  background: #fcfcfd;
}

.advanced-summary {
  justify-content: space-between;
  margin-bottom: 0;
}

.advanced-toggle {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: flex-end;
  flex: 0 0 auto;
}

.advanced {
  display: none;
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px dashed var(--line);
}

.advanced.show {
  display: block;
}

.custom-param-box {
  display: none;
  margin-top: 14px;
  padding: 14px;
  border: 1px solid #dbeafe;
  border-radius: 10px;
  background: #f8fbff;
}

.custom-param-box.show {
  display: block;
}

.custom-param-title {
  margin-bottom: 10px;
  color: #344054;
  font-size: 14px;
  font-weight: 600;
}

.param-list {
  display: grid;
  gap: 10px;
}

.param-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr) 42px;
  gap: 10px;
}

.option-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 18px;
  min-height: 42px;
  align-items: stretch;
}

label.check {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: #475467;
  font-size: 14px;
  cursor: pointer;
  user-select: none;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 0 18px;
  border: 1px solid #d0d5dd;
  border-radius: 9px;
  background: #fff;
  color: #344054;
  cursor: pointer;
  text-decoration: none;
  transition: background .18s ease, border-color .18s ease, color .18s ease, transform .05s ease;
}

.btn:hover {
  border-color: #93c5fd;
  background: #eff6ff;
  color: var(--primary-dark);
}

.btn:active {
  transform: translateY(1px);
}

.btn.primary {
  min-width: 150px;
  border-color: var(--primary);
  background: var(--primary);
  color: #fff;
  font-weight: 700;
}

.btn.primary:hover {
  border-color: var(--primary-dark);
  background: var(--primary-dark);
  color: #fff;
}

.btn.danger {
  width: 42px;
  padding: 0;
  border-color: #fecaca;
  color: var(--danger);
}

.btn.small {
  min-height: 34px;
  padding: 0 12px;
  font-size: 13px;
}

.result-card {
  background: #f8fafc;
}

.result-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 12px;
}

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

.toast,
.error {
  display: none;
  margin-top: 14px;
  padding: 11px 13px;
  border-radius: 9px;
  font-size: 14px;
  text-align: center;
}

.toast {
  background: #ecfdf3;
  color: #027a48;
}

.error {
  background: #fef3f2;
  color: #b42318;
}

.toast.show,
.error.show {
  display: block;
}

.seo-content {
  margin-top: 18px;
  padding-top: 14px;
  border-top: 1px solid var(--line);
  color: #667085;
  font-size: 13px;
}

.seo-content summary {
  cursor: pointer;
  color: #475467;
  font-weight: 600;
}

.seo-content h2 {
  margin: 14px 0 6px;
  color: #344054;
  font-size: 15px;
}

.seo-content p {
  margin: 0 0 10px;
}

.footer-note {
  margin-top: 16px;
  color: var(--muted);
  font-size: 12px;
  text-align: center;
}

@media (max-width: 720px) {
  .subflow {
    margin: 10px auto;
    padding: 0 10px 24px;
  }

  .hero {
    padding: 24px 16px;
  }

  .hero h1 {
    font-size: 24px;
  }

  .card {
    padding: 14px;
  }

  .step-card,
  .advanced-card {
    padding: 14px;
  }

  .advanced-summary {
    display: grid;
  }

  .advanced-toggle {
    justify-content: flex-start;
  }

  .form-row {
    grid-template-columns: 1fr;
    gap: 7px;
  }

  .form-label {
    padding-top: 0;
  }

  .param-row,
  .output-row {
    grid-template-columns: 1fr;
  }

  .btn.danger {
    width: 100%;
  }
}