:root {
  --ink: #13202c;
  --muted: #617080;
  --soft: #f4f7fa;
  --panel: #ffffff;
  --line: #d8e0e8;
  --blue: #1668b2;
  --blue-strong: #0e4d8d;
  --blue-soft: #e7f2fb;
  --green: #1f8a66;
  --green-soft: #e5f5ee;
  --amber: #b76b12;
  --amber-soft: #fff1da;
  --graphite: #1f2b36;
  --shadow: 0 18px 45px rgba(19, 32, 44, 0.12);
  --radius: 8px;
  --max: 1180px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: #ffffff;
  font-family:
    "Microsoft YaHei",
    "PingFang SC",
    "Segoe UI",
    Arial,
    sans-serif;
  line-height: 1.65;
  letter-spacing: 0;
}

img {
  display: block;
  max-width: 100%;
}

a {
  color: inherit;
  text-decoration: none;
}

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

button {
  cursor: pointer;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 24px;
  min-height: 68px;
  padding: 0 32px;
  border-bottom: 1px solid rgba(216, 224, 232, 0.84);
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(14px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  color: var(--graphite);
  white-space: nowrap;
}

.brand-mark {
  width: 28px;
  height: 28px;
  border-radius: 7px;
  background:
    linear-gradient(90deg, transparent 32%, rgba(255, 255, 255, 0.9) 32%, rgba(255, 255, 255, 0.9) 40%, transparent 40%),
    linear-gradient(0deg, transparent 30%, rgba(255, 255, 255, 0.7) 30%, rgba(255, 255, 255, 0.7) 38%, transparent 38%),
    var(--blue);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.28);
}

.top-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

.top-nav a {
  min-height: 40px;
  padding: 8px 12px;
  border-radius: var(--radius);
  color: #465565;
  font-size: 0.95rem;
}

.top-nav a:hover,
.top-nav a:focus-visible {
  color: var(--blue-strong);
  background: var(--blue-soft);
  outline: none;
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  padding: 8px 16px;
  border-radius: var(--radius);
  color: #ffffff;
  background: var(--blue);
  font-weight: 700;
  white-space: nowrap;
}

.hero {
  position: relative;
  isolation: isolate;
  min-height: 470px;
  height: calc(100svh - 220px);
  max-height: 620px;
  overflow: hidden;
  background: #111b25;
}

.hero-image {
  position: absolute;
  inset: 0;
  z-index: -2;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center right;
}

.hero-shade {
  position: absolute;
  inset: 0;
  z-index: -1;
  background:
    linear-gradient(90deg, rgba(6, 15, 25, 0.92) 0%, rgba(10, 22, 35, 0.78) 38%, rgba(10, 22, 35, 0.28) 68%, rgba(10, 22, 35, 0.08) 100%),
    linear-gradient(0deg, rgba(8, 20, 32, 0.64), rgba(8, 20, 32, 0.02) 42%);
}

.hero-content {
  width: min(100% - 48px, var(--max));
  height: 100%;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
  color: #ffffff;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--blue);
  font-size: 0.82rem;
  font-weight: 800;
  line-height: 1.35;
}

.hero .eyebrow {
  color: #8ed0ff;
}

.hero h1 {
  max-width: 760px;
  margin: 0;
  font-size: 4rem;
  line-height: 1.05;
  font-weight: 900;
}

.hero h1 span {
  display: block;
}

.hero-copy {
  max-width: 680px;
  margin: 24px 0 0;
  color: rgba(255, 255, 255, 0.86);
  font-size: 1.18rem;
}

.hero-actions,
.form-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 10px 18px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-weight: 800;
  line-height: 1.2;
  transition:
    transform 160ms ease,
    box-shadow 160ms ease,
    background 160ms ease,
    border-color 160ms ease;
}

.button:hover,
.button:focus-visible {
  transform: translateY(-1px);
  outline: none;
}

.button.primary {
  color: #ffffff;
  background: var(--blue);
  box-shadow: 0 12px 26px rgba(22, 104, 178, 0.28);
}

.button.primary:hover,
.button.primary:focus-visible {
  background: var(--blue-strong);
}

.button.secondary {
  color: #ffffff;
  border-color: rgba(255, 255, 255, 0.36);
  background: rgba(255, 255, 255, 0.1);
}

.button.secondary:hover,
.button.secondary:focus-visible {
  background: rgba(255, 255, 255, 0.18);
}

.button.secondary.dark {
  color: var(--blue-strong);
  border-color: #bdd7ed;
  background: #ffffff;
}

.button.ghost {
  color: var(--blue-strong);
  border-color: var(--line);
  background: #ffffff;
}

.button.ghost:hover,
.button.ghost:focus-visible {
  border-color: #a9c6df;
  background: var(--blue-soft);
}

.hero-metrics {
  display: grid;
  grid-template-columns: repeat(4, minmax(118px, 1fr));
  gap: 12px;
  width: min(100%, 680px);
  margin: 34px 0 0;
}

.hero-metrics div {
  min-height: 88px;
  padding: 15px;
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.08);
}

.hero-metrics dt {
  color: rgba(255, 255, 255, 0.68);
  font-size: 0.82rem;
}

.hero-metrics dd {
  margin: 4px 0 0;
  color: #ffffff;
  font-size: 1.45rem;
  font-weight: 900;
}

.section {
  padding: 82px 0;
}

.section > * {
  width: min(100% - 48px, var(--max));
  margin-left: auto;
  margin-right: auto;
}

.diagnosis-section {
  padding-top: 48px;
  background:
    linear-gradient(180deg, #ffffff 0%, #ffffff 58%, #f7fafc 100%);
}

.tinted {
  background: var(--soft);
}

.section-heading {
  margin-bottom: 34px;
}

.section-heading.compact {
  margin-bottom: 24px;
}

.section-heading.split {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 440px);
  gap: 36px;
  align-items: end;
}

.section-heading h2,
.closing h2 {
  margin: 0;
  color: var(--graphite);
  font-size: 2.25rem;
  line-height: 1.2;
}

.section-heading p:not(.eyebrow),
.closing p {
  margin: 14px 0 0;
  color: var(--muted);
}

.diagnosis-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) minmax(320px, 0.7fr);
  gap: 24px;
  align-items: start;
}

.diagnosis-form,
.diagnosis-summary,
.scenario-panel,
.spec-table-wrap,
.annotated-media,
.link-diagram,
.faq-list details,
.process-list li,
.problem-card {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
}

.diagnosis-form {
  display: grid;
  gap: 22px;
  padding: 24px;
  box-shadow: var(--shadow);
}

fieldset {
  min-width: 0;
  margin: 0;
  padding: 0;
  border: 0;
}

legend,
label > span,
.full-field > span {
  display: block;
  margin-bottom: 8px;
  color: var(--graphite);
  font-size: 0.92rem;
  font-weight: 800;
}

.choice-grid {
  display: grid;
  gap: 10px;
}

.choice-grid.two {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.choice-grid.three {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.choice {
  position: relative;
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 46px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fbfdff;
  color: #314252;
  font-weight: 700;
}

.choice input {
  width: 18px;
  height: 18px;
  accent-color: var(--blue);
}

.choice:has(input:checked) {
  border-color: #79b4e6;
  background: var(--blue-soft);
  color: var(--blue-strong);
}

.form-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

input,
select,
textarea {
  width: 100%;
  min-height: 46px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 10px 12px;
  color: var(--ink);
  background: #ffffff;
}

textarea {
  resize: vertical;
  min-height: 116px;
}

input:focus,
select:focus,
textarea:focus {
  border-color: #79b4e6;
  box-shadow: 0 0 0 4px rgba(22, 104, 178, 0.12);
  outline: none;
}

input[type="file"] {
  padding: 8px;
}

.diagnosis-summary {
  position: sticky;
  top: 92px;
  padding: 24px;
  box-shadow: var(--shadow);
}

.diagnosis-summary h3 {
  margin: 0 0 18px;
  font-size: 1.45rem;
}

.diagnosis-summary dl {
  display: grid;
  gap: 12px;
  margin: 0;
}

.diagnosis-summary dl div {
  padding-bottom: 12px;
  border-bottom: 1px solid var(--line);
}

.diagnosis-summary dt {
  color: var(--muted);
  font-size: 0.82rem;
}

.diagnosis-summary dd {
  margin: 4px 0 0;
  font-weight: 800;
}

.result-box {
  margin-top: 22px;
  padding: 16px;
  border-radius: var(--radius);
  background: var(--green-soft);
  color: #144d3b;
}

.result-box p {
  margin: 8px 0 14px;
  white-space: pre-line;
}

.summary-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.problem-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.problem-card {
  min-height: 210px;
  padding: 22px;
  transition:
    transform 160ms ease,
    border-color 160ms ease,
    box-shadow 160ms ease;
}

.problem-card:hover {
  transform: translateY(-3px);
  border-color: #b6cfe4;
  box-shadow: var(--shadow);
}

.card-index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 30px;
  border-radius: 6px;
  color: var(--blue-strong);
  background: var(--blue-soft);
  font-weight: 900;
}

.problem-card h3 {
  margin: 22px 0 10px;
  font-size: 1.25rem;
}

.problem-card p {
  margin: 0;
  color: var(--muted);
}

.flow-rail {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 14px;
}

.flow-step {
  position: relative;
  min-height: 190px;
  padding: 22px;
  border: 1px solid #cfdbe6;
  border-radius: var(--radius);
  background: #ffffff;
}

.flow-step:not(:last-child)::after {
  content: "";
  position: absolute;
  top: 42px;
  right: -15px;
  width: 16px;
  height: 2px;
  background: #9ab5cc;
}

.flow-step span {
  display: block;
  color: var(--green);
  font-weight: 900;
}

.flow-step strong {
  display: block;
  margin-top: 12px;
  font-size: 1.12rem;
}

.flow-step p {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.spec-table-wrap {
  overflow-x: auto;
}

.spec-table {
  width: 100%;
  min-width: 760px;
  border-collapse: collapse;
}

.spec-table th,
.spec-table td {
  padding: 16px 18px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: middle;
}

.spec-table thead th {
  color: var(--graphite);
  background: #edf4fa;
  font-size: 0.94rem;
}

.spec-table tbody th {
  width: 180px;
  color: var(--blue-strong);
  font-weight: 900;
}

.spec-table tbody tr:last-child th,
.spec-table tbody tr:last-child td {
  border-bottom: 0;
}

.scenario-panel {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  gap: 0;
  margin-top: 24px;
  overflow: hidden;
}

.scenario-tabs {
  display: grid;
  align-content: start;
  padding: 14px;
  gap: 8px;
  border-right: 1px solid var(--line);
  background: #fbfdff;
}

.scenario-tab {
  min-height: 46px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  background: transparent;
  color: #405263;
  text-align: left;
  font-weight: 800;
}

.scenario-tab:hover,
.scenario-tab:focus-visible,
.scenario-tab.active {
  color: var(--blue-strong);
  border-color: #bdd7ed;
  background: var(--blue-soft);
  outline: none;
}

.scenario-detail {
  min-height: 250px;
  padding: 26px;
}

.scenario-detail h3 {
  margin: 0 0 12px;
  font-size: 1.55rem;
}

.scenario-detail p {
  margin: 0 0 18px;
  color: var(--muted);
}

.scenario-detail ul {
  display: grid;
  gap: 10px;
  margin: 0;
  padding-left: 22px;
}

.materials-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(340px, 0.9fr);
  gap: 24px;
  align-items: stretch;
}

.annotated-media {
  position: relative;
  overflow: hidden;
  margin-top: 0;
  margin-bottom: 0;
  background: #0e1720;
}

.annotated-media img {
  width: 100%;
  height: 100%;
  min-height: 420px;
  object-fit: cover;
  object-position: center right;
}

.annotated-media::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(0deg, rgba(4, 12, 20, 0.62), rgba(4, 12, 20, 0.02) 45%);
  pointer-events: none;
}

.annotated-media figcaption {
  position: absolute;
  left: 18px;
  right: 18px;
  bottom: 16px;
  z-index: 2;
  color: #ffffff;
  font-weight: 700;
}

.callout {
  position: absolute;
  z-index: 3;
  display: inline-flex;
  align-items: center;
  max-width: 210px;
  min-height: 34px;
  padding: 6px 10px;
  border: 1px solid rgba(255, 255, 255, 0.45);
  border-radius: 6px;
  color: #ffffff;
  background: rgba(13, 32, 48, 0.78);
  font-size: 0.86rem;
  font-weight: 800;
}

.callout::after {
  content: "";
  position: absolute;
  width: 44px;
  height: 2px;
  background: rgba(142, 208, 255, 0.9);
}

.callout-a {
  top: 35%;
  right: 8%;
}

.callout-a::after {
  left: -44px;
}

.callout-b {
  top: 55%;
  left: 9%;
}

.callout-b::after {
  right: -44px;
}

.callout-c {
  top: 19%;
  right: 28%;
}

.callout-c::after {
  left: -44px;
}

.link-diagram {
  display: grid;
  grid-template-columns: 1fr 42px 1fr 42px 1fr;
  grid-template-rows: 1fr auto;
  gap: 12px;
  align-items: center;
  padding: 28px;
  min-height: 420px;
}

.diagram-node {
  display: grid;
  align-content: center;
  min-height: 146px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #ffffff;
}

.diagram-node span {
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 800;
}

.diagram-node strong {
  margin-top: 8px;
  color: var(--graphite);
  font-size: 1.05rem;
  line-height: 1.35;
}

.diagram-node small {
  display: block;
  margin-top: 4px;
  color: #405263;
  font-size: 0.88rem;
  font-weight: 800;
  line-height: 1.35;
}

.diagram-node.tester {
  border-color: #9fc6e8;
  background: var(--blue-soft);
}

.diagram-node.core {
  border-color: #a9d9c7;
  background: var(--green-soft);
}

.diagram-line {
  height: 2px;
  background: #9ab5cc;
}

.diagram-outputs {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
}

.diagram-outputs span {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  border-radius: var(--radius);
  color: #6b430d;
  background: var(--amber-soft);
  font-weight: 800;
}

.process-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
  margin-top: 0;
  margin-bottom: 0;
  padding-left: 0;
  list-style: none;
}

.process-list li {
  min-height: 210px;
  padding: 22px;
}

.process-list span {
  color: var(--amber);
  font-weight: 900;
}

.process-list h3 {
  margin: 18px 0 10px;
  font-size: 1.2rem;
}

.process-list p {
  margin: 0;
  color: var(--muted);
}

.faq-list {
  display: grid;
  gap: 12px;
}

.faq-list details {
  overflow: hidden;
}

.faq-list summary {
  min-height: 58px;
  padding: 17px 20px;
  color: var(--graphite);
  font-weight: 900;
  cursor: pointer;
}

.faq-list summary:focus-visible {
  outline: 3px solid rgba(22, 104, 178, 0.25);
  outline-offset: -3px;
}

.faq-list p {
  margin: 0;
  padding: 0 20px 20px;
  color: var(--muted);
}

.closing {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 28px;
  align-items: center;
}

.contact-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.contact-card {
  min-height: 210px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #ffffff;
  box-shadow: 0 12px 30px rgba(19, 32, 44, 0.08);
}

.contact-card h3 {
  margin: 0 0 16px;
  color: var(--graphite);
  font-size: 1.2rem;
}

.contact-card p {
  margin: 8px 0 0;
  color: var(--muted);
  word-break: break-word;
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  padding: 28px 32px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  background: #ffffff;
  font-size: 0.92rem;
}

@media (max-width: 1060px) {
  .site-header {
    grid-template-columns: auto auto;
  }

  .top-nav {
    display: none;
  }

  .hero h1 {
    font-size: 3.25rem;
  }

  .diagnosis-layout,
  .materials-layout,
  .section-heading.split {
    grid-template-columns: 1fr;
  }

  .diagnosis-summary {
    position: static;
  }

  .problem-grid,
  .process-list,
  .contact-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .flow-rail {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .flow-step:not(:last-child)::after {
    display: none;
  }

  .scenario-panel {
    grid-template-columns: 1fr;
  }

  .scenario-tabs {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .scenario-tab {
    text-align: center;
  }
}

@media (max-width: 720px) {
  .site-header {
    min-height: 64px;
    padding: 0 18px;
    gap: 12px;
  }

  .nav-cta {
    min-height: 38px;
    padding: 8px 12px;
    font-size: 0.9rem;
  }

  .hero {
    min-height: 430px;
    height: calc(100svh - 180px);
  }

  .hero-image {
    object-position: 68% center;
  }

  .hero-content,
  .section > * {
    width: min(100% - 32px, var(--max));
  }

  .hero h1 {
    font-size: 2.25rem;
  }

  .hero-copy {
    font-size: 1rem;
  }

  .hero-actions {
    width: 100%;
  }

  .hero-actions .button {
    flex: 1 1 180px;
  }

  .hero-metrics {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 10px;
    margin-top: 24px;
  }

  .hero-metrics div {
    min-height: 76px;
    padding: 12px;
  }

  .hero-metrics dd {
    font-size: 1.18rem;
  }

  .section {
    padding: 58px 0;
  }

  .diagnosis-section {
    padding-top: 36px;
  }

  .section-heading h2,
  .closing h2 {
    font-size: 1.7rem;
  }

  .diagnosis-form,
  .diagnosis-summary {
    padding: 18px;
  }

  .choice-grid.two,
  .choice-grid.three,
  .form-grid,
  .problem-grid,
  .process-list,
  .flow-rail,
  .diagram-outputs,
  .contact-grid,
  .closing {
    grid-template-columns: 1fr;
  }

  .choice {
    min-height: 44px;
  }

  .scenario-tabs {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .scenario-detail {
    padding: 20px;
  }

  .annotated-media img {
    min-height: 360px;
  }

  .callout {
    max-width: 168px;
    font-size: 0.78rem;
  }

  .callout::after {
    width: 26px;
  }

  .callout-a {
    top: 32%;
    right: 4%;
  }

  .callout-a::after,
  .callout-c::after {
    left: -26px;
  }

  .callout-b {
    left: 5%;
  }

  .callout-b::after {
    right: -26px;
  }

  .callout-c {
    top: 16%;
    right: 18%;
  }

  .link-diagram {
    grid-template-columns: 1fr;
    grid-template-rows: none;
    min-height: auto;
    padding: 20px;
  }

  .diagram-line {
    width: 2px;
    height: 28px;
    justify-self: center;
  }

  .diagram-node {
    min-height: 118px;
  }

  .site-footer {
    flex-direction: column;
    padding: 24px 18px;
  }
}

@media (max-width: 420px) {
  .brand span:last-child {
    max-width: 128px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
  }

  .hero h1 {
    font-size: 1.95rem;
  }

  .hero-actions {
    gap: 10px;
  }

  .button {
    width: 100%;
  }

  .section-heading h2,
  .closing h2 {
    font-size: 1.48rem;
  }

  .hero-metrics {
    grid-template-columns: 1fr 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}