:root {
  --sky-w: #f3f9ff;
  --sky-2: #e6f1fb;
  --card: #ffffff;
  --navy: #12385e;
  --navy-2: #0c2a48;
  --navy-soft: #d5e6f6;
  --orange: #ff6b3d;
  --orange-soft: #ffe3d9;
  --muted: #5c7893;
  --rule: #d3e3f2;
  --shell: 1140px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(700px 400px at 94% -8%, rgba(255, 107, 61, 0.09), transparent 62%),
    radial-gradient(600px 420px at -6% 40%, rgba(18, 56, 94, 0.07), transparent 62%),
    var(--sky-w);
  color: var(--navy-2);
  font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.78;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
p { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
img { display: block; max-width: 100%; height: auto; }
h1, h2, h3 { margin: 0; line-height: 1.3; font-weight: 800; }

.page-shell {
  width: 100%;
  max-width: var(--shell);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: rgba(243, 249, 255, 0.93);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--rule);
  box-shadow: 0 1px 0 rgba(18, 56, 94, 0.06);
}

.nav-shell {
  max-width: var(--shell);
  margin: 0 auto;
  padding: 12px 24px;
  display: flex;
  align-items: center;
  gap: 18px;
}

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

.brand img {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid var(--navy);
}

.primary-nav { margin-left: auto; }

.primary-nav ul {
  display: flex;
  align-items: center;
  gap: 22px;
  font-size: 14.5px;
  color: var(--muted);
}

.primary-nav a {
  display: inline-block;
  padding: 5px 0;
  transition: color 0.18s ease;
}

.primary-nav a:hover { color: var(--orange); }

.nav-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.nav-download {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 17px;
  border-radius: 8px;
  background: var(--navy);
  color: #f6fbff;
  font-size: 14.5px;
  font-weight: 800;
  transition: background 0.18s ease;
}

.nav-download svg {
  width: 17px;
  height: 17px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.nav-download:hover { background: var(--orange); }

.menu-toggle {
  display: none;
  width: 40px;
  height: 40px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: var(--card);
  cursor: pointer;
  padding: 0;
}

.menu-toggle span {
  display: block;
  width: 16px;
  height: 2px;
  margin: 3px auto;
  border-radius: 2px;
  background: var(--navy);
}

/* ---------- hero ---------- */
.hero {
  padding: 54px 0 48px;
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.04fr) minmax(0, 0.96fr);
  gap: 46px;
  align-items: center;
}

.hero-kicker {
  display: inline-block;
  font-size: 11.5px;
  letter-spacing: 0.16em;
  font-weight: 700;
  color: var(--navy);
  background: var(--navy-soft);
  border-radius: 4px;
  padding: 3px 10px;
}

.hero h1 {
  margin: 14px 0 11px;
  font-size: clamp(32px, 4.6vw, 51px);
  color: var(--navy);
  letter-spacing: 0.01em;
}

.hero-subtitle {
  font-size: clamp(17px, 1.9vw, 21px);
  font-weight: 700;
  color: var(--orange);
}

.hero-lead {
  margin-top: 16px;
  max-width: 480px;
  color: var(--muted);
  font-size: 15.4px;
}

.hero-actions {
  margin-top: 26px;
  display: flex;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
}

.button {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 13px 24px;
  border-radius: 8px;
  font-weight: 800;
  font-size: 15.5px;
  transition: transform 0.18s ease, background 0.18s ease;
}

.button svg {
  width: 18px;
  height: 18px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.button-primary {
  background: var(--orange);
  color: #fff9f6;
  box-shadow: 0 14px 28px rgba(255, 107, 61, 0.24);
}

.button-primary:hover {
  transform: translateY(-2px);
  background: #f4582a;
}

.button-large { padding: 15px 30px; font-size: 16.5px; }

.text-link {
  font-size: 14.5px;
  font-weight: 700;
  color: var(--navy);
  border-bottom: 1px solid var(--navy-soft);
  padding-bottom: 2px;
}

.text-link:hover { color: var(--orange); border-bottom-color: var(--orange-soft); }

.hero-tags {
  margin-top: 28px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  font-size: 13px;
  color: var(--muted);
}

.hero-tags li {
  padding: 4px 12px;
  border-radius: 6px;
  background: var(--card);
  border: 1px solid var(--rule);
}

.hero-tags b { color: var(--navy); }

/* ---------- hero speed meter ---------- */
.speed-meter {
  background: var(--card);
  border: 1px solid var(--rule);
  border-radius: 20px;
  padding: 18px 20px 16px;
  box-shadow: 0 24px 46px rgba(18, 56, 94, 0.1);
}

.meter-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--rule);
}

.meter-head p {
  font-size: 13.5px;
  font-weight: 800;
  color: var(--navy);
}

.meter-head span {
  font-size: 11px;
  color: var(--orange);
}

/* 半圆仪表：conic-gradient 弧 + 指针 + 三档刻度 */
.meter-dial {
  position: relative;
  width: 100%;
  max-width: 268px;
  height: 138px;
  margin: 20px auto 0;
  overflow: hidden;
}

.meter-arc {
  position: absolute;
  left: 50%;
  bottom: 0;
  width: 256px;
  height: 128px;
  margin-left: -128px;
  border-radius: 128px 128px 0 0;
  background: conic-gradient(from 270deg at 50% 100%,
    #b9d5ec 0deg 62deg,
    var(--navy) 62deg 112deg,
    var(--orange) 112deg 180deg,
    transparent 180deg 360deg);
}

.meter-arc::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 0;
  width: 196px;
  height: 98px;
  margin-left: -98px;
  border-radius: 98px 98px 0 0;
  background: var(--card);
}

.meter-needle {
  position: absolute;
  left: 50%;
  bottom: 0;
  width: 3px;
  height: 96px;
  margin-left: -1.5px;
  background: var(--navy-2);
  border-radius: 2px 2px 0 0;
  transform-origin: bottom center;
  transform: rotate(38deg);
  z-index: 2;
}

.meter-needle::before {
  content: "";
  position: absolute;
  left: -4px;
  top: -5px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--orange);
}

.meter-hub {
  position: absolute;
  left: 50%;
  bottom: -7px;
  width: 22px;
  height: 22px;
  margin-left: -11px;
  border-radius: 50%;
  background: var(--navy);
  border: 3px solid var(--card);
  z-index: 3;
}

.meter-value {
  position: absolute;
  left: 50%;
  bottom: 30px;
  transform: translateX(-50%);
  font-size: 30px;
  font-weight: 800;
  line-height: 1;
  color: var(--navy);
  z-index: 2;
  font-variant-numeric: tabular-nums;
}

.meter-value i {
  font-style: normal;
  font-size: 12px;
  font-weight: 700;
  color: var(--muted);
}

.meter-ticks {
  display: flex;
  justify-content: space-between;
  margin: 4px 2px 0;
  font-size: 10.5px;
  font-weight: 700;
  color: var(--muted);
  letter-spacing: 0.04em;
}

.meter-ticks li:last-child { color: var(--orange); }

.meter-foot {
  margin-top: 11px;
  padding-top: 10px;
  border-top: 1px dashed var(--rule);
  font-size: 11.5px;
  color: var(--muted);
}

/* ---------- section shared ---------- */
section { padding: 54px 0; }

.section-heading {
  max-width: 690px;
  margin-bottom: 28px;
}

.section-heading .eyebrow {
  display: inline-block;
  font-size: 11px;
  letter-spacing: 0.18em;
  font-weight: 700;
  color: var(--orange);
  margin-bottom: 9px;
}

.section-heading h2 {
  font-size: clamp(23px, 2.8vw, 31px);
  color: var(--navy);
}

.section-heading p:last-child {
  margin-top: 10px;
  color: var(--muted);
  font-size: 14.4px;
}

.section-heading-split {
  max-width: none;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
}

.section-heading-split > p {
  margin: 0 0 6px;
  color: var(--muted);
  font-size: 13.4px;
  white-space: nowrap;
}

/* ---------- features / meter grid ---------- */
.features {
  background: linear-gradient(180deg, var(--sky-2), var(--sky-w));
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
}

.meter-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 13px;
  align-items: end;
}

.meter-grid article {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 18px 17px 20px;
  background: var(--card);
  border: 1px solid var(--rule);
  border-radius: 10px 10px 3px 3px;
  border-bottom: 5px solid var(--navy-soft);
}

.meter-grid article:nth-child(1) { min-height: 176px; }
.meter-grid article:nth-child(2) { min-height: 200px; }
.meter-grid article:nth-child(3) { min-height: 224px; border-bottom-color: var(--orange); }
.meter-grid article:nth-child(4) { min-height: 194px; }

.meter-grid span {
  display: inline-block;
  width: 26px;
  font-size: 10.5px;
  font-weight: 800;
  letter-spacing: 0.08em;
  color: var(--orange);
  border-bottom: 2px solid var(--orange-soft);
  margin-bottom: 4px;
}

.meter-grid h3 {
  font-size: 17px;
  color: var(--navy);
}

.meter-grid p {
  font-size: 13.4px;
  color: var(--muted);
}

/* ---------- shots ---------- */
.meter-shots {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
}

.meter-shots figure {
  margin: 0;
  border-radius: 12px;
  overflow: hidden;
  background: var(--card);
  border: 1px solid var(--rule);
  box-shadow: 0 12px 24px rgba(18, 56, 94, 0.06);
}

.meter-shots img {
  width: 100%;
  aspect-ratio: 9 / 16;
  object-fit: cover;
  object-position: top center;
  background: var(--sky-2);
}

.meter-shots figcaption {
  display: flex;
  align-items: baseline;
  gap: 7px;
  padding: 10px 13px 12px;
  font-size: 13px;
  font-weight: 700;
  color: var(--navy);
}

.meter-shots figcaption b {
  font-size: 11px;
  color: var(--orange);
}

.meter-shots figcaption small {
  margin-left: auto;
  font-weight: 400;
  font-size: 10.5px;
  color: var(--muted);
}

.sample-note {
  margin-top: 16px;
  font-size: 12.4px;
  color: var(--muted);
}

/* ---------- faq ---------- */
.faq {
  background: var(--navy);
  color: #eaf3fb;
}

.faq .section-heading h2 { color: #f7fbff; }
.faq .section-heading .eyebrow { color: #ffb49c; }
.faq .section-heading p:last-child { color: #a9c2d8; }

.faq-rows {
  display: grid;
  gap: 9px;
  max-width: 920px;
}

.faq-rows details {
  border-radius: 8px;
  background: rgba(243, 249, 255, 0.07);
  border: 1px solid rgba(243, 249, 255, 0.16);
  padding: 0 18px;
  transition: background 0.18s ease;
}

.faq-rows details[open] { background: rgba(243, 249, 255, 0.12); }

.faq-rows summary {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 0;
  cursor: pointer;
  list-style: none;
}

.faq-rows summary::-webkit-details-marker { display: none; }

.faq-rows summary h3 {
  flex: 1;
  font-size: 15.5px;
  color: #f7fbff;
}

.faq-rows summary i {
  position: relative;
  flex: none;
  width: 21px;
  height: 21px;
  border-radius: 5px;
  background: var(--orange);
}

.faq-rows summary i::before,
.faq-rows summary i::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  background: #fff8f5;
  border-radius: 2px;
  transform: translate(-50%, -50%);
}

.faq-rows summary i::before { width: 9px; height: 2px; }
.faq-rows summary i::after { width: 2px; height: 9px; transition: opacity 0.2s ease; }
.faq-rows details[open] summary i::after { opacity: 0; }

.faq-rows details > p {
  padding: 12px 0 16px;
  border-top: 1px dashed rgba(243, 249, 255, 0.2);
  font-size: 14px;
  color: #c5d8e8;
}

/* ---------- reviews ---------- */
.reviews { border-top: 1px solid var(--rule); }

.note-wall {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.review-card {
  padding: 16px 17px;
  border-radius: 10px;
  background: var(--card);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--orange);
}

.review-card > p {
  font-size: 13.8px;
  color: #24445f;
}

.review-meta {
  margin-top: 12px;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
  padding-top: 9px;
  border-top: 1px dashed var(--rule);
  font-size: 11px;
  color: var(--muted);
}

.review-meta b {
  font-size: 12px;
  color: var(--navy);
}

/* ---------- steps ---------- */
.meter-steps {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 13px;
}

.meter-steps li {
  padding: 20px 20px 22px;
  border-radius: 10px;
  background: var(--card);
  border: 1px solid var(--rule);
  border-top: 3px solid var(--navy-soft);
}

.meter-steps li:nth-child(3) { border-top-color: var(--orange); }

.meter-steps span {
  font-size: 10.5px;
  font-weight: 800;
  letter-spacing: 0.12em;
  color: var(--muted);
}

.meter-steps h3 {
  font-size: 17.5px;
  margin: 3px 0 5px;
  color: var(--navy);
}

.meter-steps p {
  font-size: 13.6px;
  color: var(--muted);
}

/* ---------- download ---------- */
.download { padding-bottom: 66px; }

.download-panel {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 34px;
  padding: 34px;
  border-radius: 18px;
  background:
    radial-gradient(420px 240px at 92% 0%, rgba(255, 107, 61, 0.16), transparent 66%),
    linear-gradient(120deg, #eaf4ff, #dbe9f8);
  border: 1px solid var(--rule);
}

.download-copy { max-width: 520px; }

.download-copy .eyebrow {
  font-size: 11px;
  letter-spacing: 0.18em;
  font-weight: 700;
  color: var(--orange);
  margin-bottom: 8px;
}

.download-copy h2 {
  font-size: clamp(23px, 2.7vw, 30px);
  color: var(--navy);
  margin-bottom: 8px;
}

.download-copy p { font-size: 14.4px; color: var(--muted); }

.download-act {
  flex: none;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 12px;
}

.download-notes {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
  font-size: 12px;
  color: var(--muted);
}

.download-notes li {
  display: inline-flex;
  align-items: center;
  gap: 5px;
}

.download-notes li::before {
  content: "";
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--orange);
}

/* ---------- footer ---------- */
.site-footer {
  background: var(--navy-2);
  color: #dde9f5;
  padding: 34px 0 30px;
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr) minmax(0, 0.8fr);
  gap: 22px 30px;
  align-items: start;
}

.footer-brand strong {
  display: block;
  font-size: 17px;
  color: #f7fbff;
}

.footer-brand p {
  margin-top: 4px;
  font-size: 12.5px;
  color: #9db9d2;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  font-size: 13px;
  color: #aec7dc;
}

.footer-nav a:hover { color: #ffb49c; }

.footer-meta {
  font-size: 12.5px;
  color: #9db9d2;
  text-align: right;
}

.footer-meta a { color: #d5e6f6; }

.disclaimer {
  grid-column: 1 / -1;
  padding-top: 16px;
  border-top: 1px solid rgba(243, 249, 255, 0.14);
  font-size: 12px;
  line-height: 1.7;
  color: #8aa6c0;
}

/* ---------- responsive ---------- */
@media (max-width: 980px) {
  .hero-grid { grid-template-columns: minmax(0, 1fr); gap: 34px; }
  .speed-meter { max-width: 520px; }
  .meter-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); align-items: stretch; }
  .meter-grid article { min-height: 0 !important; }
  .meter-shots { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .note-wall { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-meta { text-align: left; }
  .download-panel { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 900px) {
  .primary-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    margin-left: 0;
    display: none;
    background: var(--card);
    border-bottom: 1px solid var(--rule);
    padding: 8px 24px 14px;
  }

  .primary-nav.is-open { display: block; }

  .primary-nav ul {
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    font-size: 15px;
  }

  .primary-nav li { width: 100%; }

  .primary-nav a {
    display: block;
    padding: 11px 0;
    border-bottom: 1px solid var(--rule);
  }

  .nav-shell { position: relative; flex-wrap: wrap; }
  .primary-nav { order: 4; flex-basis: 100%; }
  .nav-actions { margin-left: auto; }
  .menu-toggle { display: block; }
  .nav-download span { display: none; }
  .nav-download { padding: 10px 12px; }
}

@media (max-width: 640px) {
  .page-shell, .nav-shell { padding-left: 18px; padding-right: 18px; }
  section { padding: 42px 0; }
  .hero { padding: 38px 0 34px; }
  .meter-grid { grid-template-columns: minmax(0, 1fr); }
  .meter-shots { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; }
  .note-wall { grid-template-columns: minmax(0, 1fr); }
  .meter-steps { grid-template-columns: minmax(0, 1fr); }
  .section-heading-split { flex-direction: column; align-items: flex-start; gap: 6px; }
  .section-heading-split > p { white-space: normal; }
  .download-panel { padding: 26px 20px; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .download-act { width: 100%; }
  .download-act .button { width: 100%; justify-content: center; }
}

@media (max-width: 400px) {
  .brand span { font-size: 15px; }
  .meter-shots { grid-template-columns: minmax(0, 1fr); }
  .speed-meter { padding: 15px 14px 13px; }
  .meter-dial { height: 126px; max-width: 230px; }
  .meter-arc { width: 220px; height: 110px; margin-left: -110px; border-radius: 110px 110px 0 0; }
  .meter-arc::after { width: 168px; height: 84px; margin-left: -84px; border-radius: 84px 84px 0 0; }
  .meter-needle { height: 84px; }
  .meter-value { bottom: 26px; font-size: 26px; }
  .meter-ticks { margin: 2px 0 0; }
}