:root {
  --bg: #F5F8FD;
  --surface: #FFFFFF;
  --ink: #101D31;
  --muted: #61748B;
  --primary: #3E63F2;
  --primary-deep: #2D4FD3;
  --cyan: #2698E8;
  --mint: #1DBE9F;
  --orange: #F5A623;
  --violet: #7C5CE7;
  --line: rgba(25, 54, 92, .09);
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  /* 断点约定：xs ≤599 | sm 600–899 | md 900–1199 | lg ≥1200
     新增 media query 只允许使用 419.98 / 599.98 / 899.98 / 1199.98 四个值。 */
  --touch: 44px;
  --tap-gap: 8px;
  --fs-min: 12.5px;
  --r-sm: 10px;
  --r-md: 14px;
  --r-lg: 20px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 110px;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1,
h2,
h3,
h4,
p {
  margin: 0;
}

ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

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

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

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

::selection {
  background: rgba(62, 99, 242, .18);
}

:where(a, button):focus-visible {
  outline: 3px solid rgba(62, 99, 242, .38);
  outline-offset: 3px;
}

.container {
  width: min(1180px, calc(100% - 48px));
  margin-inline: auto;
}

.skip-link {
  position: fixed;
  top: -100px;
  left: 18px;
  z-index: 200;
  padding: 10px 18px;
  border-radius: 10px;
  background: var(--ink);
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  transition: top .2s ease;
}

.skip-link:focus {
  top: 16px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  border-radius: 14px;
  font-weight: 700;
  white-space: nowrap;
  transition: transform .22s ease, box-shadow .22s ease, background-color .22s ease;
}

.btn-sm {
  padding: 10px 20px;
  border-radius: 10px;
  font-size: 14px;
}

.btn-lg {
  padding: 16px 28px;
  border-radius: 14px;
  font-size: 15.5px;
}

.btn-primary {
  color: #fff;
  background-image: linear-gradient(115deg, #3E63F2 0%, #2E8FED 58%, #1DB6C2 125%);
  box-shadow: 0 12px 26px rgba(62, 99, 242, .26), inset 0 1px 0 rgba(255, 255, 255, .24);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 18px 34px rgba(62, 99, 242, .32), inset 0 1px 0 rgba(255, 255, 255, .24);
}

.btn-primary:active {
  transform: translateY(0);
}

.icon-arrow {
  transition: transform .22s ease;
}

.btn:hover .icon-arrow {
  transform: translateX(3px);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  padding-top: 16px;
  pointer-events: none;
}

.header-inner {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 70px;
  padding: 0 12px 0 18px;
  border: 1px solid rgba(255, 255, 255, .86);
  border-radius: 20px;
  background: rgba(255, 255, 255, .72);
  box-shadow: 0 12px 36px rgba(30, 60, 110, .08);
  -webkit-backdrop-filter: blur(18px) saturate(1.35);
  backdrop-filter: blur(18px) saturate(1.35);
  pointer-events: auto;
  transition: background-color .25s ease, border-color .25s ease, box-shadow .25s ease;
}

.site-header.is-scrolled .header-inner {
  background: rgba(255, 255, 255, .92);
  border-color: rgba(30, 60, 110, .08);
  box-shadow: 0 14px 40px rgba(30, 60, 110, .12);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex: none;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 14px;
  background-image: linear-gradient(135deg, #3E63F2, #21BFA6);
  box-shadow: 0 9px 20px rgba(62, 99, 242, .24), inset 0 1px 0 rgba(255, 255, 255, .25);
  transition: transform .3s ease;
}

.brand:hover .brand-mark {
  transform: rotate(-6deg);
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.brand-text strong {
  font-size: 17px;
  font-weight: 800;
  letter-spacing: .03em;
}

.brand-text small {
  margin-top: 4px;
  font-size: 12.5px;
  font-weight: 500;
  color: var(--muted);
  letter-spacing: .13em;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-link {
  padding: 10px 16px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 600;
  color: #53677F;
  transition: color .2s ease, background-color .2s ease;
}

.nav-link:hover {
  color: var(--primary);
  background: rgba(62, 99, 242, .06);
}

.nav-link.is-active {
  color: var(--primary);
  background: rgba(62, 99, 242, .09);
}

.nav-cta {
  margin-left: 10px;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  width: 42px;
  height: 42px;
  border: 1px solid rgba(25, 54, 92, .08);
  border-radius: 14px;
  background: rgba(255, 255, 255, .8);
}

.nav-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: var(--ink);
  transition: transform .25s ease, opacity .2s ease;
}

.nav-toggle.is-open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle.is-open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.is-open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.hero {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  padding: 66px 0 74px;
}

.hero::before {
  content: "";
  position: absolute;
  z-index: -2;
  inset: -160px -8% -40px;
  background:
    radial-gradient(620px 460px at 86% 12%, rgba(80, 128, 255, .18), transparent 68%),
    radial-gradient(560px 480px at 2% 58%, rgba(42, 204, 177, .12), transparent 70%),
    radial-gradient(440px 340px at 52% 100%, rgba(255, 183, 94, .08), transparent 72%);
  pointer-events: none;
}

.hero::after {
  content: "";
  position: absolute;
  z-index: -1;
  inset: 0;
  background-image:
    linear-gradient(rgba(42, 75, 125, .045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(42, 75, 125, .045) 1px, transparent 1px);
  background-size: 56px 56px;
  -webkit-mask-image: linear-gradient(to bottom, #000 0%, transparent 88%);
  mask-image: linear-gradient(to bottom, #000 0%, transparent 88%);
  opacity: .65;
  pointer-events: none;
}

.hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1.02fr) minmax(0, .98fr);
  align-items: center;
  gap: 48px;
}

.hero-copy > * {
  animation: heroIn .75s cubic-bezier(.16, 1, .3, 1) backwards;
}

.hero-copy > *:nth-child(1) { animation-delay: .03s; }
.hero-copy > *:nth-child(2) { animation-delay: .1s; }
.hero-copy > *:nth-child(3) { animation-delay: .17s; }
.hero-copy > *:nth-child(4) { animation-delay: .24s; }
.hero-copy > *:nth-child(5) { animation-delay: .31s; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 13px;
  border: 1px solid rgba(62, 99, 242, .12);
  border-radius: 999px;
  background: rgba(255, 255, 255, .66);
  box-shadow: 0 6px 18px rgba(45, 79, 140, .05);
  color: #3158C9;
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: .02em;
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
}

.eyebrow-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--mint);
  box-shadow: 0 0 0 4px rgba(29, 190, 159, .13);
  animation: pulse 2.6s ease-in-out infinite;
}

.hero h1 {
  margin-top: 24px;
  font-size: clamp(46px, 5.8vw, 70px);
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -.05em;
}

.headline-line {
  position: relative;
  display: block;
  width: fit-content;
}

.grad {
  color: var(--primary);
  background-image: linear-gradient(100deg, #3E63F2 5%, #2D96ED 48%, #19BFA4 98%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.squiggle {
  position: absolute;
  left: 1%;
  bottom: -.08em;
  width: 98%;
  height: .18em;
  opacity: .9;
}

.hero-lead {
  max-width: 480px;
  margin-top: 24px;
  font-size: 16px;
  line-height: 1.9;
  color: var(--muted);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 32px;
}

.hero-social {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
  margin-top: 34px;
}

.avatar-stack {
  display: flex;
  padding-left: 10px;
}

.avatar {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  margin-left: -10px;
  border: 2px solid #fff;
  border-radius: 50%;
  box-shadow: 0 5px 12px rgba(16, 36, 62, .09);
  font-size: 12.5px;
  font-weight: 800;
  color: #1E3A5F;
}

.avatar:nth-child(1) { background: #C9E0FF; }
.avatar:nth-child(2) { background: #CFEFE7; }
.avatar:nth-child(3) { background: #FFE6C2; }
.avatar:nth-child(4) { background: #E6DCFF; }

.hero-social p {
  font-size: 13.5px;
  color: var(--muted);
}

.hero-social strong {
  color: var(--ink);
  font-weight: 800;
}

.dot-sep {
  margin: 0 7px;
  color: #A9BBCD;
}

.hero-visual {
  position: relative;
  width: 100%;
  max-width: 560px;
  margin-left: auto;
  padding: 16px 18px 4px;
  border: 1px solid rgba(255, 255, 255, .95);
  border-radius: 32px;
  background: linear-gradient(145deg, rgba(255, 255, 255, .9), rgba(240, 247, 255, .7));
  box-shadow: 0 30px 80px rgba(35, 70, 125, .13), inset 0 1px 0 rgba(255, 255, 255, .9);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  animation: heroIn .9s .18s cubic-bezier(.16, 1, .3, 1) backwards;
}

.stage-top {
  position: relative;
  z-index: 3;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 0 2px;
  color: #5A6679;
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: .16em;
}

.stage-dots {
  display: flex;
  gap: 5px;
}

.stage-dots i {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #DCE5F0;
}

.stage-dots i:nth-child(1) { background: #FF9B8A; }
.stage-dots i:nth-child(2) { background: #FFC766; }
.stage-dots i:nth-child(3) { background: #5DDABD; }

.stage-title {
  margin-right: auto;
}

.stage-index {
  color: #A9B8CA;
  letter-spacing: .08em;
}

.hero-art {
  width: 100%;
  height: auto;
  margin-top: -4px;
  overflow: visible;
  filter: drop-shadow(0 26px 32px rgba(34, 73, 140, .1));
}

.hero-art .drift,
.hero-art .robot-bob,
.hero-art .robot-eyes {
  transform-box: fill-box;
  transform-origin: center;
}

.hero-art .drift {
  animation: drift 6s ease-in-out infinite;
}

.hero-art .drift-slow {
  animation-duration: 7.5s;
}

.hero-art .drift-fast {
  animation-duration: 5.2s;
  animation-delay: .6s;
}

.hero-art .drift-flask {
  animation-duration: 6.8s;
  animation-delay: .3s;
}

.hero-art .robot-bob {
  animation: drift 7s ease-in-out infinite;
}

.hero-art .robot-eyes {
  animation: blink 7s ease-in-out infinite;
}

.float-chip {
  position: absolute;
  z-index: 2;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 13px;
  border: 1px solid rgba(255, 255, 255, .9);
  border-radius: 14px;
  background: rgba(255, 255, 255, .88);
  box-shadow: 0 14px 30px rgba(31, 70, 130, .14);
  font-size: 12.5px;
  font-weight: 700;
  color: var(--ink);
  pointer-events: none;
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  animation: chipFloat 5.6s ease-in-out infinite;
}

.chip-icon {
  display: grid;
  place-items: center;
  width: 22px;
  height: 22px;
  border-radius: 7px;
  color: #fff;
}

.ci-blue { background-image: linear-gradient(135deg, #3E63F2, #39A9FF); }
.ci-mint { background-image: linear-gradient(135deg, #12B8A0, #5FE0B4); }
.ci-orange { background-image: linear-gradient(135deg, #FF9E3D, #FFC46A); }

.chip-arduino {
  top: 22%;
  left: -12px;
  --rot: -5deg;
}

.chip-python {
  bottom: 14%;
  left: -4px;
  --rot: 4deg;
  animation-delay: 1.1s;
}

.chip-3d {
  top: 31%;
  right: -12px;
  --rot: 5deg;
  animation-delay: .6s;
}

.stats {
  position: relative;
  z-index: 2;
  padding: 0 0 88px;
}

.stats-panel {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.stat {
  --stat-accent: var(--primary);
  --stat-glow: rgba(62, 99, 242, .12);
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 20px;
  padding: 24px;
  border: 1px solid rgba(226, 235, 246, .95);
  border-radius: 24px;
  background: rgba(255, 255, 255, .85);
  box-shadow: 0 12px 32px rgba(30, 62, 110, .055);
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease;
}

.stat:nth-child(2) {
  --stat-accent: #12A98B;
  --stat-glow: rgba(29, 190, 159, .12);
}

.stat:nth-child(3) {
  --stat-accent: #E28A16;
  --stat-glow: rgba(245, 166, 35, .13);
}

.stat:nth-child(4) {
  --stat-accent: #7C5CE7;
  --stat-glow: rgba(124, 92, 231, .12);
}

.stat::before {
  content: "";
  position: absolute;
  top: -46px;
  right: -42px;
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background: var(--stat-glow);
  opacity: 0;
  pointer-events: none;
  transition: opacity .25s ease;
}

.stat::after {
  content: "";
  position: absolute;
  left: 24px;
  right: 24px;
  bottom: 0;
  height: 2px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--stat-accent), transparent);
  opacity: 0;
  transform: scaleX(.4);
  transform-origin: left;
  transition: opacity .25s ease, transform .25s ease;
}

.stat:hover {
  transform: translateY(-5px);
  border-color: rgba(62, 99, 242, .18);
  box-shadow: 0 22px 46px rgba(35, 70, 125, .11);
}

.stat:hover::before {
  opacity: 1;
}

.stat:hover::after {
  opacity: .7;
  transform: scaleX(1);
}

.stat-icon {
  position: relative;
  display: grid;
  place-items: center;
  flex: none;
  width: 46px;
  height: 46px;
  border-radius: 14px;
}

.stat-icon svg {
  width: 22px;
  height: 22px;
}

.stat-blue { color: var(--primary); background: #EAF0FF; }
.stat-mint { color: #0E9F83; background: #E4F8F1; }
.stat-orange { color: #5A6679; background: #FFF2DF; }
.stat-purple { color: #7C5CE7; background: #F0EBFF; }

.stat-number {
  display: flex;
  align-items: baseline;
  font-size: 34px;
  font-weight: 800;
  line-height: 1;
  letter-spacing: -.04em;
  font-variant-numeric: tabular-nums;
}

.suffix {
  margin-left: 4px;
  font-size: 14px;
  font-weight: 700;
  color: #72849A;
}

.stat-label {
  margin-top: 8px;
  font-size: 13px;
  color: var(--muted);
}

.site-footer {
  position: relative;
  overflow: hidden;
  border-radius: 32px 32px 0 0;
  background:
    radial-gradient(600px 340px at 90% 0%, rgba(62, 99, 242, .18), transparent 70%),
    radial-gradient(480px 320px at 0% 100%, rgba(29, 190, 159, .1), transparent 70%),
    #0C1A2D;
  color: #9CAFC5;
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(105, 160, 255, .55), rgba(75, 224, 197, .35), transparent);
}

.footer-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1.4fr .7fr 1fr;
  gap: 64px;
  padding: 64px 0 44px;
}

.footer-about .brand {
  margin-bottom: 20px;
}

.footer-about .brand-text strong {
  color: #fff;
}

.footer-about .brand-text small {
  color: #5A6679;
}

.footer-about p {
  max-width: 430px;
  font-size: 14px;
  line-height: 1.95;
}

.footer-motto {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 24px;
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: .24em;
  color: #68DBC1;
}

.footer-motto::before {
  content: "";
  width: 26px;
  height: 1px;
  background: rgba(104, 219, 193, .45);
}

.footer-col h3 {
  margin-bottom: 20px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: .08em;
  color: #F2F6FB;
}

.footer-links {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 12px;
}

.footer-link {
  display: inline-block;
  font-size: 14px;
  color: #5A6679;
  text-align: left;
  transition: color .2s ease, transform .2s ease;
}

.footer-link:hover {
  color: #fff;
  transform: translateX(3px);
}

.footer-contact {
  display: flex;
}

.qq-card {
  display: flex;
  align-items: center;
  gap: 13px;
  width: fit-content;
  padding: 14px 18px;
  border: 1px solid rgba(255, 255, 255, .1);
  border-radius: 14px;
  background: rgba(255, 255, 255, .055);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .04);
}

.qq-card svg {
  flex: none;
  width: 21px;
  height: 21px;
  color: #7BA7FF;
}

.qq-label {
  display: block;
  font-size: 12.5px;
  letter-spacing: .08em;
  color: #5A6679;
}

.qq-number {
  display: block;
  margin-top: 2px;
  color: #fff;
  font-size: 18px;
  font-weight: 700;
  letter-spacing: .04em;
  font-variant-numeric: tabular-nums;
}

.footer-bottom {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  padding: 20px 0 28px;
  border-top: 1px solid rgba(255, 255, 255, .08);
  font-size: 12.5px;
  color: #7188A3;
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 26px;
  z-index: 200;
  display: flex;
  align-items: center;
  gap: 10px;
  max-width: calc(100% - 40px);
  padding: 13px 20px;
  border: 1px solid rgba(255, 255, 255, .1);
  border-radius: 999px;
  background: rgba(13, 28, 48, .92);
  color: #fff;
  box-shadow: 0 18px 40px rgba(9, 25, 45, .3);
  font-size: 14px;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: translate(-50%, 18px);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  transition: opacity .25s ease, transform .25s ease, visibility .25s ease;
}

.toast::before {
  content: "";
  flex: none;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: linear-gradient(135deg, #6FE3C8, #4F9DFF);
  box-shadow: 0 0 0 4px rgba(111, 227, 200, .12);
}

.toast.is-show {
  opacity: 1;
  visibility: visible;
  transform: translate(-50%, 0);
}

.js .reveal {
  opacity: 0;
}

.js .reveal.is-visible {
  opacity: 1;
  animation: revealIn .75s cubic-bezier(.16, 1, .3, 1) backwards;
  animation-delay: var(--delay, 0s);
}

.stats-panel .stat:nth-child(2) { --delay: .08s; }
.stats-panel .stat:nth-child(3) { --delay: .16s; }
.stats-panel .stat:nth-child(4) { --delay: .24s; }

@keyframes heroIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes revealIn {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 4px rgba(29, 190, 159, .13); }
  50% { box-shadow: 0 0 0 7px rgba(29, 190, 159, .05); }
}

@keyframes drift {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-9px); }
}

@keyframes blink {
  0%, 92%, 100% { transform: scaleY(1); }
  96% { transform: scaleY(.12); }
}

@keyframes chipFloat {
  0%, 100% { transform: translateY(0) rotate(var(--rot, 0deg)); }
  50% { transform: translateY(-9px) rotate(var(--rot, 0deg)); }
}

@media (max-width: 1199.98px) {
  .hero {
    padding: 52px 0 64px;
  }

  .hero-grid {
    grid-template-columns: 1fr;
    gap: 42px;
  }

  .hero-copy {
    max-width: 680px;
    margin: 0 auto;
    text-align: center;
  }

  .headline-line {
    margin-inline: auto;
  }

  .hero h1 {
    font-size: clamp(44px, 7vw, 60px);
  }

  .hero-lead {
    margin-inline: auto;
  }

  .hero-actions,
  .hero-social {
    justify-content: center;
  }

  .hero-visual {
    max-width: 560px;
    margin: 0 auto;
  }

  .hero::after {
    opacity: .45;
  }
}

@media (max-width: 899.98px) {
  .header-inner {
    min-height: 66px;
  }

  .nav-toggle {
    display: flex;
  }

  .site-nav {
    position: absolute;
    top: calc(100% + 10px);
    left: 0;
    right: 0;
    z-index: 90;
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
    padding: 10px;
    border: 1px solid rgba(255, 255, 255, .9);
    border-radius: 20px;
    background: rgba(255, 255, 255, .96);
    box-shadow: 0 24px 50px rgba(24, 56, 110, .16);
    -webkit-backdrop-filter: blur(18px);
    backdrop-filter: blur(18px);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(-8px);
    transition: opacity .22s ease, transform .22s ease, visibility .22s ease;
  }

  .site-nav.is-open {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: none;
  }

  .nav-link {
    padding: 12px 14px;
    border-radius: 10px;
  }

  .nav-cta {
    margin: 6px 4px 4px;
  }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    padding-top: 56px;
  }

  .footer-about {
    grid-column: 1 / -1;
  }

  .footer-about p {
    max-width: 600px;
  }
}

@media (max-width: 899.98px) {
  .stats-panel {
    grid-template-columns: 1fr 1fr;
    gap: 14px;
  }

  .stat {
    padding: 22px;
  }
}

@media (max-width: 599.98px) {
  .container {
    width: calc(100% - 32px);
  }

  .site-header {
    padding-top: 10px;
  }

  .header-inner {
    min-height: 64px;
    padding: 0 8px 0 12px;
    border-radius: 20px;
  }

  .brand {
    gap: 10px;
  }

  .brand-mark {
    width: 38px;
    height: 38px;
    border-radius: 10px;
  }

  .brand-text strong {
    font-size: 16px;
  }

  .brand-text small {
    font-size: 12.5px;
    letter-spacing: .12em;
  }

  .nav-toggle {
    width: 40px;
    height: 40px;
  }

  .site-nav {
    top: calc(100% + 8px);
    padding: 8px;
    border-radius: 14px;
  }

  .hero {
    padding: 36px 0 52px;
  }

  .hero-grid {
    gap: 34px;
  }

  .eyebrow {
    padding: 6px 11px;
    font-size: 12.5px;
  }

  .hero h1 {
    margin-top: 20px;
    font-size: clamp(38px, 11vw, 48px);
    letter-spacing: -.045em;
  }

  .squiggle {
    bottom: -5px;
    height: 9px;
  }

  .hero-lead {
    max-width: 360px;
    margin-top: 20px;
    font-size: 14.5px;
    line-height: 1.85;
  }

  .hero-actions {
    margin-top: 26px;
  }

  .hero-actions .btn {
    width: 100%;
    max-width: 320px;
    padding: 15px 20px;
    font-size: 14.5px;
  }

  .hero-social {
    flex-direction: column;
    margin-top: 26px;
    gap: 12px;
  }

  .hero-social p {
    font-size: 12.5px;
    text-align: center;
  }

  .avatar {
    width: 32px;
    height: 32px;
    margin-left: -9px;
    font-size: 12.5px;
  }

  .hero-visual {
    max-width: 440px;
    padding: 12px 12px 0;
    border-radius: 26px;
  }

  .stage-top {
    gap: 10px;
    font-size: 12.5px;
  }

  .float-chip {
    gap: 6px;
    padding: 7px 10px;
    border-radius: 10px;
    font-size: 12.5px;
  }

  .chip-icon {
    width: 20px;
    height: 20px;
    border-radius: 6px;
  }

  .chip-arduino { top: 22%; left: 6px; }
  .chip-python { bottom: 12%; left: 8px; }
  .chip-3d { top: 30%; right: 6px; }

  .stats {
    padding-bottom: 64px;
  }

  .stats-panel {
    gap: 12px;
  }

  .stat {
    gap: 16px;
    padding: 18px;
    border-radius: 20px;
  }

  .stat::after {
    left: 18px;
    right: 18px;
  }

  .stat-icon {
    width: 42px;
    height: 42px;
    border-radius: 14px;
  }

  .stat-icon svg {
    width: 20px;
    height: 20px;
  }

  .stat-number {
    font-size: 28px;
  }

  .suffix {
    font-size: 13px;
  }

  .stat-label {
    margin-top: 7px;
    font-size: 12.5px;
  }

  .site-footer {
    border-radius: 26px 26px 0 0;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
    padding: 44px 0 34px;
  }

  .footer-about {
    grid-column: auto;
  }

  .footer-about p {
    font-size: 13.5px;
  }

  .footer-col h3 {
    margin-bottom: 14px;
  }

  .qq-card {
    padding: 13px 16px;
  }

  .footer-bottom {
    flex-direction: column;
    gap: 4px;
    padding: 18px 0 24px;
    font-size: 12.5px;
  }

  .toast {
    bottom: 18px;
    width: calc(100% - 32px);
    justify-content: center;
    padding: 12px 16px;
    border-radius: 20px;
    font-size: 13px;
    text-align: center;
  }
}

@media (max-width: 419.98px) {
  .stats-panel {
    gap: 10px;
  }

  .stat {
    gap: 14px;
    padding: 14px;
  }

  .stat-icon {
    width: 38px;
    height: 38px;
    border-radius: 10px;
  }

  .stat-number {
    font-size: 24px;
  }

  .suffix {
    font-size: 12.5px;
  }

  .stat-label {
    font-size: 12.5px;
  }

  .float-chip {
    font-size: 12.5px;
  }

  .chip-3d {
    display: none;
  }
}

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

  *,
  *::before,
  *::after {
    animation-duration: .01ms !important;
    animation-delay: 0s !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }

  .js .reveal {
    opacity: 1;
  }
}

/* ============================================================
   触控下限（方案 3 / 9）：xs/sm 站点控件 ≥44×44
   ============================================================ */

@media (max-width: 899.98px) {
  .brand {
    display: inline-flex;
    align-items: center;
    min-height: var(--touch);
  }

  .nav-toggle {
    width: var(--touch);
    height: var(--touch);
  }

  .nav-link {
    display: flex;
    align-items: center;
    min-height: var(--touch);
  }

  .footer-link {
    display: inline-flex;
    align-items: center;
    min-width: var(--touch);
    min-height: var(--touch);
  }

  .btn {
    min-height: var(--touch);
  }
}