/* ==========================================================================
   Stuben — www.stuben.cn
   Plain CSS, no build step. System font stack (no external font requests,
   so the page loads fast inside and outside mainland China).
   ========================================================================== */

:root {
  --c-bg: #ffffff;
  --c-bg-alt: #f6f7fb;
  --c-text: #0f172a;
  --c-muted: #475569;
  --c-border: #e2e8f0;
  --c-primary: #4f46e5;
  --c-primary-dark: #4338ca;
  --c-accent: #ec4899;
  --c-video: #f97316;
  --c-dark: #0f172a;

  --font-sans: "Inter", ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;

  --radius: 16px;
  --radius-sm: 10px;
  --shadow-sm: 0 1px 2px rgb(15 23 42 / 0.06), 0 1px 3px rgb(15 23 42 / 0.08);
  --shadow: 0 10px 30px -12px rgb(15 23 42 / 0.18);
  --shadow-lg: 0 30px 60px -20px rgb(15 23 42 / 0.3);

  --container: 1140px;
  --header-h: 68px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 12px);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  line-height: 1.65;
  color: var(--c-text);
  background: var(--c-bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3 {
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin: 0 0 0.5em;
}
h1 { font-size: clamp(2.25rem, 5vw + 0.5rem, 3.75rem); font-weight: 800; }
h2 { font-size: clamp(1.75rem, 2.5vw + 0.75rem, 2.5rem); font-weight: 750; }
h3 { font-size: 1.2rem; font-weight: 700; letter-spacing: -0.01em; }

p { margin: 0 0 1em; }
a { color: var(--c-primary); text-underline-offset: 3px; }
a:hover { color: var(--c-primary-dark); }
ul, ol { padding: 0; margin: 0; list-style: none; }
img, svg { display: block; max-width: 100%; }

:focus-visible {
  outline: 3px solid var(--c-primary);
  outline-offset: 3px;
  border-radius: 6px;
}

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

.skip-link {
  position: absolute; left: 1rem; top: -100px; z-index: 100;
  background: var(--c-text); color: #fff; padding: 0.6rem 1rem; border-radius: 8px;
  text-decoration: none; font-weight: 600;
}
.skip-link:focus { top: 1rem; color: #fff; }

.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: 1.25rem;
}
.container.narrow { max-width: 820px; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.7rem 1.2rem;
  border-radius: 999px;
  border: 2px solid transparent;
  font: inherit;
  font-weight: 650;
  font-size: 0.975rem;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.15s ease, background-color 0.2s ease, color 0.2s ease,
    border-color 0.2s ease, box-shadow 0.2s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn-sm { padding: 0.45rem 1rem; font-size: 0.9rem; }
.btn-lg { padding: 0.9rem 1.5rem; font-size: 1.025rem; }

.btn-primary {
  background: var(--c-primary);
  color: #fff;
  box-shadow: 0 8px 20px -8px rgb(79 70 229 / 0.6);
}
.btn-primary:hover { background: var(--c-primary-dark); color: #fff; }

.btn-ghost {
  background: transparent;
  color: var(--c-text);
  border-color: var(--c-border);
}
.btn-ghost:hover { border-color: var(--c-text); color: var(--c-text); }

.btn-light { background: #fff; color: var(--c-dark); }
.btn-light:hover { background: #eef2ff; color: var(--c-dark); }

.btn-outline-light {
  background: transparent;
  color: #fff;
  border-color: rgb(255 255 255 / 0.5);
}
.btn-outline-light:hover { border-color: #fff; background: rgb(255 255 255 / 0.08); }

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--header-h);
  background: rgb(255 255 255 / 0.82);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.site-header.is-scrolled {
  border-bottom-color: var(--c-border);
  box-shadow: var(--shadow-sm);
}

.nav {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: var(--c-text);
  font-weight: 800;
  font-size: 1.2rem;
  letter-spacing: -0.02em;
}
.brand:hover { color: var(--c-text); }
.brand-mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
  color: #fff;
  font-size: 1.05rem;
}

.nav-menu ul {
  display: flex;
  align-items: center;
  gap: 1.75rem;
}
.nav-menu a:not(.btn) {
  color: var(--c-muted);
  text-decoration: none;
  font-weight: 550;
  font-size: 0.975rem;
}
.nav-menu a:not(.btn):hover { color: var(--c-text); }

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  border: 0;
  background: transparent;
  border-radius: 10px;
  cursor: pointer;
  position: relative;
}
.nav-toggle-bar,
.nav-toggle-bar::before,
.nav-toggle-bar::after {
  position: absolute;
  left: 11px;
  width: 22px;
  height: 2px;
  background: var(--c-text);
  border-radius: 2px;
  transition: transform 0.25s ease, opacity 0.2s ease;
}
.nav-toggle-bar { top: 21px; }
.nav-toggle-bar::before,
.nav-toggle-bar::after { content: ""; left: 0; }
.nav-toggle-bar::before { top: -7px; }
.nav-toggle-bar::after { top: 7px; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar { background: transparent; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar::before { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar::after { transform: translateY(-7px) rotate(-45deg); }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  overflow: hidden;
  padding: clamp(3.5rem, 8vw, 6.5rem) 0 clamp(3.5rem, 7vw, 6rem);
  background:
    radial-gradient(60rem 30rem at 85% -10%, rgb(236 72 153 / 0.12), transparent 60%),
    radial-gradient(50rem 30rem at -10% 10%, rgb(79 70 229 / 0.12), transparent 60%);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 3rem;
  align-items: center;
}

.eyebrow {
  display: inline-block;
  margin-bottom: 1rem;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-primary);
}

.accent {
  background: linear-gradient(90deg, var(--c-primary), var(--c-accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.lead {
  font-size: clamp(1.075rem, 0.6vw + 0.95rem, 1.25rem);
  color: var(--c-muted);
  max-width: 36rem;
  margin-bottom: 2rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  margin-bottom: 2rem;
}

.hero-points {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.5rem;
  color: var(--c-muted);
  font-size: 0.95rem;
  font-weight: 550;
}
.hero-points li {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
}
.hero-points li::before {
  content: "";
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
}

/* Decorative device mockups (pure CSS) */
.hero-visual {
  position: relative;
  min-height: 440px;
}
.device { position: absolute; box-shadow: var(--shadow-lg); }

.phone {
  width: 220px;
  height: 440px;
  right: 8%;
  top: 0;
  border-radius: 36px;
  background: #111827;
  padding: 10px;
  transform: rotate(4deg);
  animation: float 7s ease-in-out infinite;
}
.phone-notch {
  position: absolute;
  top: 16px;
  left: 50%;
  width: 70px;
  height: 18px;
  margin-left: -35px;
  border-radius: 999px;
  background: #111827;
  z-index: 2;
}
.phone-screen {
  height: 100%;
  border-radius: 28px;
  background: linear-gradient(180deg, #eef2ff, #fff);
  padding: 44px 16px 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.ui-bar { height: 12px; width: 55%; border-radius: 6px; background: #c7d2fe; }
.ui-card {
  border-radius: 14px;
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  background: #fff;
  box-shadow: var(--shadow-sm);
}
.ui-card span { display: block; height: 8px; border-radius: 4px; background: #e2e8f0; }
.ui-card span:first-child { width: 70%; background: #a5b4fc; }
.ui-card-b span:first-child { background: #f9a8d4; }
.ui-chart {
  flex: 1;
  display: flex;
  align-items: flex-end;
  gap: 8px;
  padding: 12px;
  border-radius: 14px;
  background: #fff;
  box-shadow: var(--shadow-sm);
}
.ui-chart i {
  flex: 1;
  height: var(--h);
  border-radius: 6px 6px 2px 2px;
  background: linear-gradient(180deg, var(--c-primary), #a5b4fc);
}
.ui-button {
  height: 38px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--c-primary), var(--c-accent));
}

.player {
  width: 320px;
  left: 0;
  bottom: 10px;
  border-radius: 18px;
  background: #0f172a;
  overflow: hidden;
  transform: rotate(-3deg);
  animation: float 8s ease-in-out infinite reverse;
}
.player-frame {
  aspect-ratio: 16 / 9;
  display: grid;
  place-items: center;
  background:
    linear-gradient(135deg, rgb(249 115 22 / 0.85), rgb(236 72 153 / 0.85)),
    #1e293b;
}
.play-btn {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: rgb(255 255 255 / 0.95);
  position: relative;
  box-shadow: 0 8px 20px rgb(0 0 0 / 0.25);
}
.play-btn::after {
  content: "";
  position: absolute;
  left: 22px;
  top: 17px;
  border-style: solid;
  border-width: 11px 0 11px 18px;
  border-color: transparent transparent transparent var(--c-video);
}
.player-controls {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  color: #cbd5e1;
  font-size: 0.75rem;
  font-variant-numeric: tabular-nums;
}
.player-progress {
  flex: 1;
  height: 4px;
  border-radius: 4px;
  background: #334155;
  overflow: hidden;
}
.player-progress span {
  display: block;
  width: 70%;
  height: 100%;
  background: var(--c-video);
}

@keyframes float {
  0%, 100% { translate: 0 0; }
  50% { translate: 0 -10px; }
}

/* ---------- Sections ---------- */
.section { padding: clamp(4rem, 8vw, 6.5rem) 0; }
.section-alt { background: var(--c-bg-alt); }

.section-head {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 3rem;
}
.section-sub { color: var(--c-muted); font-size: 1.075rem; }

/* ---------- Services ---------- */
.service-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}
.service-card {
  padding: 2.25rem;
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  background: #fff;
  transition: box-shadow 0.25s ease, transform 0.25s ease, border-color 0.25s ease;
}
.service-card:hover {
  box-shadow: var(--shadow);
  transform: translateY(-3px);
  border-color: transparent;
}
.service-card > p { color: var(--c-muted); }

.service-icon {
  display: grid;
  place-items: center;
  width: 56px;
  height: 56px;
  margin-bottom: 1.25rem;
  border-radius: 14px;
  color: var(--c-primary);
  background: #eef2ff;
}
.service-icon.video { color: var(--c-video); background: #fff7ed; }

.check-list { display: grid; gap: 0.55rem; margin-top: 1.25rem; }
.check-list li {
  position: relative;
  padding-left: 1.75rem;
  font-weight: 500;
}
.check-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.35em;
  width: 1.1rem;
  height: 1.1rem;
  border-radius: 50%;
  background:
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='3.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M5 12.5 10 17 19 7'/%3E%3C/svg%3E") center / 65% no-repeat,
    var(--c-primary);
}
.service-icon.video ~ .check-list li::before { background-color: var(--c-video); }

/* ---------- Work / examples ---------- */
.filters {
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  margin-bottom: 2.25rem;
}
.filter {
  font: inherit;
  font-weight: 600;
  font-size: 0.95rem;
  padding: 0.5rem 1.15rem;
  border-radius: 999px;
  border: 1px solid var(--c-border);
  background: #fff;
  color: var(--c-muted);
  cursor: pointer;
  transition: all 0.2s ease;
}
.filter:hover { color: var(--c-text); border-color: #cbd5e1; }
.filter.is-active {
  background: var(--c-text);
  border-color: var(--c-text);
  color: #fff;
}

.work-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.25rem;
}
.work-card {
  display: flex;
  flex-direction: column;
  border-radius: var(--radius);
  background: #fff;
  border: 1px solid var(--c-border);
  overflow: hidden;
  transition: box-shadow 0.25s ease, transform 0.25s ease;
}
.work-card:hover { box-shadow: var(--shadow); transform: translateY(-4px); }
.work-card[hidden] { display: none; }

.work-thumb {
  aspect-ratio: 16 / 10;
  display: grid;
  place-items: center;
  font-size: 2.75rem;
}
.work-thumb span {
  display: grid;
  place-items: center;
  width: 76px;
  height: 76px;
  border-radius: 20px;
  background: rgb(255 255 255 / 0.85);
  box-shadow: var(--shadow-sm);
}
.thumb-1 { background: linear-gradient(135deg, #c7d2fe, #e0e7ff); }
.thumb-2 { background: linear-gradient(135deg, #bbf7d0, #dcfce7); }
.thumb-3 { background: linear-gradient(135deg, #bae6fd, #e0f2fe); }
.thumb-4 { background: linear-gradient(135deg, #fde68a, #fef3c7); }
.thumb-5 { background: linear-gradient(135deg, #fed7aa, #ffedd5); }
.thumb-6 { background: linear-gradient(135deg, #fbcfe8, #fce7f3); }
.thumb-7 { background: linear-gradient(135deg, #fecdd3, #ffe4e6); }
.thumb-8 { background: linear-gradient(135deg, #ddd6fe, #ede9fe); }

.work-body {
  padding: 1.25rem 1.25rem 1.4rem;
  display: flex;
  flex-direction: column;
  flex: 1;
}
.work-body h3 { font-size: 1.075rem; margin: 0.6rem 0 0.4rem; }
.work-body p { color: var(--c-muted); font-size: 0.935rem; line-height: 1.6; }

.tag {
  align-self: flex-start;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
}
.tag-app { background: #eef2ff; color: var(--c-primary-dark); }
.tag-video { background: #fff7ed; color: #c2410c; }

.meta {
  margin-top: auto;
  padding-top: 0.9rem;
  border-top: 1px dashed var(--c-border);
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem 1rem;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--c-muted);
}

/* ---------- Process ---------- */
.steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
  counter-reset: step;
}
.step {
  position: relative;
  padding: 1.75rem 1.5rem;
  border-radius: var(--radius);
  background: var(--c-bg-alt);
}
.step p { color: var(--c-muted); font-size: 0.975rem; margin: 0; }
.step-num {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  margin-bottom: 1rem;
  border-radius: 12px;
  font-weight: 800;
  color: #fff;
  background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
}

/* ---------- FAQ ---------- */
.faq { display: grid; gap: 0.75rem; }
.faq details {
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  background: #fff;
  transition: box-shadow 0.2s ease;
}
.faq details[open] { box-shadow: var(--shadow-sm); }
.faq summary {
  list-style: none;
  cursor: pointer;
  padding: 1.1rem 3rem 1.1rem 1.25rem;
  font-weight: 650;
  position: relative;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
  content: "+";
  position: absolute;
  right: 1.25rem;
  top: 50%;
  translate: 0 -50%;
  font-size: 1.4rem;
  font-weight: 400;
  color: var(--c-primary);
  transition: rotate 0.2s ease;
}
.faq details[open] summary::after { rotate: 45deg; }
.faq details p { padding: 0 1.25rem 1.2rem; margin: 0; color: var(--c-muted); }

/* ---------- Contact ---------- */
.contact {
  background:
    radial-gradient(40rem 20rem at 10% 0%, rgb(236 72 153 / 0.35), transparent 60%),
    radial-gradient(40rem 20rem at 90% 100%, rgb(79 70 229 / 0.5), transparent 60%),
    var(--c-dark);
  color: #fff;
}
.contact-box { text-align: center; }
.contact-box p { color: #cbd5e1; font-size: 1.125rem; max-width: 38rem; margin-inline: auto; }
.contact-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.8rem;
  margin-top: 2rem;
}
.contact :focus-visible { outline-color: #fff; }
.copy-status { min-height: 1.6em; margin-top: 1rem; font-size: 0.95rem !important; }

/* ---------- Footer ---------- */
.site-footer {
  background: var(--c-dark);
  color: #94a3b8;
  border-top: 1px solid rgb(255 255 255 / 0.08);
  font-size: 0.9rem;
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.5rem 2rem;
  padding-block: 1.75rem;
}
.footer-inner p { margin: 0; }
.site-footer a { color: #e2e8f0; text-decoration: none; }
.site-footer a:hover { color: #fff; text-decoration: underline; }

/* ---------- Reveal on scroll (enabled by JS) ---------- */
.js .reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.js .reveal.is-visible { opacity: 1; transform: none; }

/* ---------- Responsive ---------- */
@media (max-width: 1024px) {
  .work-grid { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 860px) {
  .hero-grid { grid-template-columns: 1fr; gap: 2.5rem; }
  .hero-visual { min-height: 400px; max-width: 460px; width: 100%; margin-inline: auto; }
  .phone { width: 190px; height: 380px; right: 4%; }
  .player { width: 270px; }
  .service-grid { grid-template-columns: 1fr; }

  .nav-toggle { display: block; }
  .nav-menu {
    position: absolute;
    top: var(--header-h);
    left: 0;
    right: 0;
    background: #fff;
    border-bottom: 1px solid var(--c-border);
    box-shadow: var(--shadow);
    padding: 0.75rem 1.25rem 1.25rem;
    display: none;
  }
  .nav-menu.is-open { display: block; }
  .nav-menu ul { flex-direction: column; align-items: stretch; gap: 0.25rem; }
  .nav-menu a:not(.btn) { display: block; padding: 0.75rem 0.25rem; font-size: 1.05rem; }
  .nav-menu .btn { margin-top: 0.5rem; width: 100%; padding-block: 0.8rem; }
}

@media (max-width: 560px) {
  body { font-size: 1rem; }
  .work-grid, .steps { grid-template-columns: 1fr; }
  .hero-actions .btn { flex: 1 1 100%; }
  .hero-visual { min-height: 340px; }
  .phone { width: 160px; height: 320px; border-radius: 30px; }
  .phone-screen { border-radius: 22px; padding-top: 38px; }
  .player { width: 230px; }
  .service-card { padding: 1.75rem; }
  .contact-actions .btn { flex: 1 1 100%; }
  .footer-inner { flex-direction: column; text-align: center; align-items: center; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .js .reveal { opacity: 1; transform: none; }
}