:root {
  --teams: #5b5fc7;
  --teams-hover: #4f52b2;
  --teams-press: #464775;
  --teams-soft: #7f85f5;
  --teams-tint: #f5f5ff;
  --teams-line: #e8ebfa;
  --ink: #242424;
  --muted: #616161;
  --line: #ebebeb;
  --paper: #ffffff;
  --canvas: #faf9f8;
  --shadow: 0 2px 4px rgba(0, 0, 0, 0.04), 0 12px 40px rgba(70, 71, 117, 0.12);
  --radius: 8px;
  --radius-lg: 12px;
  --font: "Segoe UI Variable", "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  --max: 1160px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: var(--teams);
  text-underline-offset: 0.15em;
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--teams-press);
  color: #fff;
  padding: 0.75rem 1rem;
  z-index: 100;
}

.skip-link:focus {
  left: 1rem;
  top: 1rem;
}

.wrap {
  width: min(100% - 2.5rem, var(--max));
  margin-inline: auto;
}

.wrap.narrow {
  width: min(100% - 2.5rem, 720px);
}

/* Header — Microsoft-like thin bar */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid transparent;
}

.site-header.is-scrolled {
  border-bottom-color: var(--line);
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.04);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 1rem;
  min-height: 56px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  text-decoration: none;
  color: var(--ink);
  flex-shrink: 0;
}

.brand-logo {
  width: 28px;
  height: 30px;
}

.brand-text small {
  display: block;
  font-size: 0.68rem;
  font-weight: 600;
  color: var(--muted);
  line-height: 1.1;
}

.brand-text strong {
  display: block;
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.15;
}

.nav {
  display: flex;
  gap: 1.35rem;
  margin-left: auto;
  margin-right: 0.75rem;
}

.nav a {
  color: var(--ink);
  text-decoration: none;
  font-size: 0.92rem;
  font-weight: 500;
}

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

/* Buttons — Fluent style (not pills) */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  min-height: 40px;
  padding: 0.55rem 1.15rem;
  border-radius: var(--radius);
  border: 1px solid transparent;
  font: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
}

.btn-primary {
  background: var(--teams);
  color: #fff;
}

.btn-primary:hover {
  background: var(--teams-hover);
}

.btn-secondary {
  background: transparent;
  color: var(--teams);
  border-color: var(--teams);
}

.btn-secondary:hover {
  background: var(--teams-tint);
}

.btn-ghost {
  background: transparent;
  color: var(--teams);
  border-color: #d1d1d1;
  min-height: 36px;
  padding-inline: 0.9rem;
  font-size: 0.88rem;
}

.btn-ghost:hover {
  background: var(--teams-tint);
  border-color: var(--teams);
}

.btn-large {
  min-height: 48px;
  padding-inline: 1.4rem;
  font-size: 1rem;
}

/* Hero — light official marketing plane */
.hero {
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(900px 420px at 85% 10%, rgba(127, 133, 245, 0.22), transparent 55%),
    linear-gradient(180deg, #f0f0ff 0%, #ffffff 68%);
  color: var(--ink);
  padding: 3.5rem 0 2.5rem;
}

.hero-visual {
  display: none;
}

.hero-copy {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 2.5rem;
  align-items: center;
  animation: rise 0.7s ease both;
}

.hero-logo-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.hero-logo {
  width: 48px;
  height: 51px;
}

.brand-signal {
  margin: 0;
  font-size: 1.35rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.hero h1 {
  margin: 0 0 0.85rem;
  max-width: 14ch;
  font-size: clamp(2.1rem, 4.2vw, 3.15rem);
  font-weight: 700;
  letter-spacing: -0.035em;
  line-height: 1.12;
  color: var(--ink);
}

.lede {
  margin: 0 0 1.5rem;
  max-width: 36rem;
  color: var(--muted);
  font-size: 1.125rem;
  line-height: 1.55;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
}

.hero-art {
  justify-self: end;
  width: min(100%, 560px);
  filter: drop-shadow(0 28px 56px rgba(70, 71, 117, 0.28));
}

.hero-art img {
  width: 100%;
  height: auto;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(91, 95, 199, 0.14);
  background: #fff;
}

.illust-frame {
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: 0 16px 48px rgba(70, 71, 117, 0.18);
  border: 1px solid var(--teams-line);
  background: #fff;
}

.illust-frame img {
  width: 100%;
  height: auto;
  display: block;
}

.meet-strip {
  margin-top: 2rem;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: 0 16px 40px rgba(70, 71, 117, 0.2);
  border: 1px solid rgba(91, 95, 199, 0.16);
}

.meet-strip img {
  width: 100%;
  height: auto;
  display: block;
}

/* Sections */
.section {
  padding: 4.5rem 0;
}

.section h2 {
  margin: 0 0 0.75rem;
  font-size: clamp(1.65rem, 2.8vw, 2.15rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--ink);
}

.section-intro {
  margin: 0 0 1.75rem;
  max-width: 40rem;
  color: var(--muted);
  font-size: 1.05rem;
}

.section-web {
  background: var(--paper);
}

.section-secondary {
  background: var(--canvas);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: 3.5rem 0;
}

.section-faq {
  background: var(--paper);
}

.section-content {
  background: var(--teams-tint);
}

.split {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 3rem;
  align-items: center;
}

.section-head {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.section-head img {
  width: 40px;
  height: 42px;
}

.section-head h2 {
  margin: 0;
}

.checklist {
  margin: 1rem 0 1.5rem;
  padding: 0;
  list-style: none;
}

.checklist li {
  position: relative;
  padding-left: 1.65rem;
  margin-bottom: 0.65rem;
  color: var(--muted);
}

.checklist li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.45rem;
  width: 0.85rem;
  height: 0.85rem;
  border-radius: 50%;
  background:
    radial-gradient(circle at 50% 45%, #fff 0 28%, transparent 30%),
    var(--teams);
}

.feature-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
  margin-top: 2rem;
}

.feature-row article {
  padding: 1.35rem 1.25rem;
  border-radius: var(--radius-lg);
  background: #fff;
  border: 1px solid var(--line);
}

.feature-row h3 {
  margin: 0 0 0.45rem;
  font-size: 1.05rem;
  font-weight: 650;
}

.feature-row p {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.platform-icon {
  width: 40px;
  height: 40px;
  margin-bottom: 0.85rem;
  border-radius: 10px;
}

.download-pair {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
}

.download-pair article {
  padding: 1.5rem 1.4rem;
  border-radius: var(--radius-lg);
  background: #fff;
  border: 1px solid var(--line);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
}

.download-pair h3 {
  margin: 0 0 0.4rem;
  font-size: 1.1rem;
}

.download-pair p {
  margin: 0 0 1.1rem;
  color: var(--muted);
  font-size: 0.95rem;
}

.content-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.content-grid article {
  padding: 1.5rem 1.4rem;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
}

.content-grid h3 {
  margin: 0 0 0.5rem;
  font-size: 1.12rem;
}

.content-grid p {
  margin: 0;
  color: var(--muted);
}

.faq-list details {
  border-bottom: 1px solid var(--line);
  padding: 1rem 0;
}

.faq-list summary {
  cursor: pointer;
  font-weight: 650;
  color: var(--ink);
  list-style: none;
}

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

.faq-list summary::after {
  content: "+";
  float: right;
  color: var(--teams);
  font-weight: 600;
}

.faq-list details[open] summary::after {
  content: "–";
}

.faq-list details p {
  margin: 0.7rem 0 0.15rem;
  color: var(--muted);
  max-width: 40rem;
}

.section-cta {
  background: linear-gradient(180deg, #ffffff, #f5f5ff);
  text-align: center;
}

.cta-band h2 {
  margin-bottom: 0.45rem;
}

.cta-band p {
  margin: 0 auto 1.35rem;
  color: var(--muted);
  max-width: 32rem;
}

.cta-band .cta-row {
  justify-content: center;
}

.site-footer {
  background: #201f1e;
  color: rgba(255, 255, 255, 0.86);
  padding: 2.5rem 0;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  margin-bottom: 0.75rem;
}

.footer-brand img {
  width: 32px;
  height: 34px;
}

.footer-inner p {
  margin: 0 0 0.5rem;
}

.fineprint {
  color: rgba(255, 255, 255, 0.55);
  font-size: 0.85rem;
  max-width: 42rem;
}

.site-footer nav {
  display: flex;
  flex-wrap: wrap;
  gap: 1.1rem;
  margin-top: 1.1rem;
}

.site-footer a {
  color: #c9cbef;
  text-decoration: none;
  font-size: 0.92rem;
}

.site-footer a:hover {
  text-decoration: underline;
}

.page-hero {
  padding: 3.5rem 0 2rem;
  background: linear-gradient(180deg, #f0f0ff, #fff);
}

.page-hero h1 {
  margin: 0 0 0.6rem;
  font-size: clamp(1.8rem, 3vw, 2.4rem);
  letter-spacing: -0.03em;
}

.page-hero p {
  margin: 0;
  max-width: 40rem;
  color: var(--muted);
  font-size: 1.05rem;
}

.steps {
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: step;
  display: grid;
  gap: 0.9rem;
}

.steps li {
  position: relative;
  padding: 0.95rem 1rem 0.95rem 3.25rem;
  background: var(--paper);
  border: 1px solid var(--teams-line);
  border-radius: var(--radius);
  color: var(--ink);
}

.steps li::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: 0.85rem;
  top: 50%;
  transform: translateY(-50%);
  width: 1.75rem;
  height: 1.75rem;
  border-radius: 50%;
  background: var(--teams);
  color: #fff;
  font-size: 0.85rem;
  font-weight: 700;
  display: grid;
  place-items: center;
}

.article-meta {
  margin: 0.5rem 0 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.article-body h2 {
  margin: 2rem 0 0.75rem;
  font-size: 1.35rem;
}

.article-body p {
  margin: 0 0 1rem;
  color: var(--ink);
  line-height: 1.7;
}

.article-body a {
  font-weight: 600;
}

.back-link {
  margin-top: 2rem;
}

.content-grid h3 a {
  color: var(--ink);
  text-decoration: none;
}

.content-grid h3 a:hover {
  color: var(--teams);
}

.reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.reveal.is-in {
  opacity: 1;
  transform: none;
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(14px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@media (max-width: 900px) {
  .nav {
    display: none;
  }

  .split,
  .download-pair,
  .feature-row,
  .content-grid,
  .hero-copy {
    grid-template-columns: 1fr;
  }

  .hero-art {
    order: -1;
    justify-self: stretch;
    width: min(100%, 400px);
    margin-inline: auto;
  }

  .hero h1 {
    max-width: none;
  }
}

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

  .hero-copy,
  .reveal,
  .btn {
    animation: none !important;
    transition: none !important;
    transform: none !important;
    opacity: 1 !important;
  }
}