:root {
  --bg: #070b12;
  --bg-elevated: #0d1522;
  --accent: #3ee0c5;
  --accent-2: #4f8cff;
  --text: #e8eef8;
  --muted: #8b9bb4;
  --line: rgba(62, 224, 197, 0.18);
  --font-display: "Orbitron", "Segoe UI", "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-body: "DM Sans", "PingFang SC", "Microsoft YaHei", "Noto Sans SC", "Segoe UI", sans-serif;
}

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

html {
  scroll-behavior: smooth;
  overflow-x: clip;
}

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  overflow-x: clip;
}

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

a { color: var(--accent); }

.container {
  width: min(100% - 2rem, 1120px);
  margin-inline: auto;
}

.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;
}

/* —— Buttons —— */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  min-height: 2.75rem;
  padding: 0.7rem 1.35rem;
  border-radius: 0.35rem;
  border: 1px solid transparent;
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease, box-shadow 0.2s ease;
}

.btn--primary {
  color: #041016;
  background: var(--accent);
  border-color: var(--accent);
  box-shadow: 0 0 0 1px rgba(62, 224, 197, 0.15);
}

.btn--primary:hover {
  background: #56ebd0;
  border-color: #56ebd0;
  color: #041016;
}

.btn--ghost {
  color: var(--text);
  background: transparent;
  border-color: rgba(232, 238, 248, 0.35);
}

.btn--ghost:hover {
  color: var(--accent);
  border-color: var(--accent);
}

.btn:focus-visible,
.site-header__brand:focus-visible,
.site-header__nav a:focus-visible,
.site-footer a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

/* —— Sticky header —— */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  padding: 0.85rem 0;
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background-color 0.25s ease, border-color 0.25s ease, backdrop-filter 0.25s ease;
}

.site-header.is-scrolled {
  background: rgba(7, 11, 18, 0.88);
  border-bottom-color: var(--line);
  backdrop-filter: blur(12px);
}

.site-header__inner {
  display: flex;
  align-items: center;
  gap: 1.25rem;
}

.site-header__brand {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--text);
  text-decoration: none;
  white-space: nowrap;
}

.site-header__brand:hover {
  color: var(--accent);
}

.site-header__nav {
  display: none;
  flex: 1;
  justify-content: center;
  gap: 1.35rem;
}

.site-header__nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.92rem;
  font-weight: 500;
  transition: color 0.2s ease;
}

.site-header__nav a:hover {
  color: var(--text);
}

.site-header__cta {
  margin-left: auto;
  min-height: 2.35rem;
  padding: 0.45rem 1rem;
  font-size: 0.88rem;
}

@media (min-width: 860px) {
  .site-header__nav {
    display: flex;
  }

  .site-header__cta {
    margin-left: 0;
  }
}

/* —— Hero —— */
.hero {
  position: relative;
  isolation: isolate;
  display: flex;
  align-items: center;
  min-height: min(100vh, 56rem);
  padding: 5.5rem 0 4.5rem;
  overflow: hidden;
  background-color: var(--bg);
  background-image:
    radial-gradient(ellipse 90% 70% at 70% 20%, rgba(79, 140, 255, 0.22), transparent 55%),
    radial-gradient(ellipse 70% 55% at 15% 75%, rgba(62, 224, 197, 0.14), transparent 50%),
    radial-gradient(ellipse 100% 80% at 50% 100%, rgba(13, 21, 34, 0.95), transparent 60%),
    repeating-linear-gradient(
      0deg,
      transparent,
      transparent 47px,
      rgba(62, 224, 197, 0.045) 47px,
      rgba(62, 224, 197, 0.045) 48px
    ),
    repeating-linear-gradient(
      90deg,
      transparent,
      transparent 47px,
      rgba(79, 140, 255, 0.04) 47px,
      rgba(79, 140, 255, 0.04) 48px
    );
}

.hero__glow {
  position: absolute;
  inset: auto;
  top: -12%;
  right: -8%;
  width: min(68vw, 42rem);
  height: min(68vw, 42rem);
  border-radius: 50%;
  background:
    radial-gradient(circle at 40% 40%, rgba(62, 224, 197, 0.28), transparent 55%),
    radial-gradient(circle at 70% 60%, rgba(79, 140, 255, 0.22), transparent 50%);
  filter: blur(28px);
  pointer-events: none;
  z-index: 0;
  animation: drift 16s ease-in-out infinite alternate;
}

.hero__content {
  position: relative;
  z-index: 1;
  max-width: 46rem;
  animation: hero-rise 0.9s ease-out both;
}

.hero__brand {
  margin: 0 0 1.1rem;
  font-family: var(--font-display);
  font-size: clamp(2.1rem, 6.5vw, 3.6rem);
  font-weight: 700;
  letter-spacing: 0.12em;
  line-height: 1.1;
  color: var(--text);
  text-shadow: 0 0 40px rgba(62, 224, 197, 0.18);
}

.hero__title {
  margin: 0 0 1.15rem;
  font-family: var(--font-display);
  font-size: clamp(1.45rem, 4.2vw, 2.35rem);
  font-weight: 600;
  letter-spacing: 0.04em;
  line-height: 1.35;
  color: var(--text);
}

.hero__lead {
  margin: 0 0 1rem;
  max-width: 38rem;
  font-size: clamp(1rem, 2.2vw, 1.15rem);
  color: var(--muted);
}

.hero__tags {
  margin: 0 0 1.85rem;
  font-size: 0.92rem;
  letter-spacing: 0.08em;
  color: rgba(139, 155, 180, 0.9);
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
}

@keyframes drift {
  from {
    transform: translate3d(0, 0, 0) scale(1);
  }
  to {
    transform: translate3d(-6%, 8%, 0) scale(1.08);
  }
}

@keyframes hero-rise {
  from {
    opacity: 0;
    transform: translateY(1.25rem);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 640px) {
  .hero {
    min-height: 100svh;
    padding: 4.25rem 0 2.25rem;
    align-items: center;
  }

  .hero__brand {
    margin-bottom: 0.85rem;
    font-size: clamp(1.85rem, 9vw, 2.4rem);
  }

  .hero__title {
    margin-bottom: 0.85rem;
    font-size: clamp(1.2rem, 6.2vw, 1.5rem);
  }

  .hero__lead {
    margin-bottom: 0.75rem;
    font-size: 0.98rem;
  }

  .hero__tags {
    margin-bottom: 1.35rem;
    font-size: 0.85rem;
  }

  .hero__actions {
    flex-direction: column;
    align-items: stretch;
  }

  .hero__actions .btn {
    width: 100%;
  }
}

@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;
  }

  .hero__glow {
    animation: none;
  }

  .hero__content {
    animation: none;
  }
}

/* —— Scroll reveal —— */
.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

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

@media (prefers-reduced-motion: reduce) {
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* —— Content sections —— */
.section {
  padding: clamp(4rem, 8vw, 7rem) 0;
}

.section--solution {
  background:
    radial-gradient(ellipse 80% 60% at 50% 0%, rgba(79, 140, 255, 0.08), transparent 55%),
    var(--bg);
  border-block: 1px solid var(--line);
}

.section--pilot {
  background:
    radial-gradient(ellipse 70% 50% at 80% 100%, rgba(62, 224, 197, 0.06), transparent 50%),
    var(--bg);
}

.section__title {
  margin: 0 0 1.25rem;
  max-width: 42rem;
  font-family: var(--font-display);
  font-size: clamp(1.35rem, 3.5vw, 1.85rem);
  font-weight: 600;
  letter-spacing: 0.03em;
  line-height: 1.35;
  color: var(--text);
}

.section__lead {
  margin: 0 0 2.25rem;
  max-width: 38rem;
  font-size: clamp(1rem, 2vw, 1.1rem);
  color: var(--muted);
}

.section__note {
  margin: 2.5rem 0 0;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
  max-width: 38rem;
  font-size: 0.95rem;
  color: var(--muted);
}

.feature-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.feature-grid__item {
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--line);
}

.feature-grid__item:first-child {
  border-top: 1px solid var(--line);
}

.feature-grid__title {
  margin: 0 0 0.45rem;
  font-family: var(--font-body);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
}

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

@media (min-width: 720px) {
  .feature-grid--pain {
    grid-template-columns: repeat(3, 1fr);
    border: 1px solid var(--line);
  }

  .feature-grid--pain .feature-grid__item {
    padding: 1.75rem 1.5rem;
    border-bottom: none;
    border-top: none;
  }

  .feature-grid--pain .feature-grid__item:not(:last-child) {
    border-right: 1px solid var(--line);
  }

  .feature-grid--pain .feature-grid__item:first-child {
    border-top: none;
  }

  .feature-grid--solution {
    grid-template-columns: repeat(2, 1fr);
    column-gap: 2.5rem;
  }

  .feature-grid--solution .feature-grid__item:nth-child(odd) {
    border-right: 1px solid var(--line);
    padding-right: 2.5rem;
  }

  .feature-grid--solution .feature-grid__item:nth-child(-n + 2) {
    border-top: 1px solid var(--line);
  }

  .feature-grid--solution .feature-grid__item:nth-child(3) {
    border-top: none;
  }

  .feature-grid--pilot {
    grid-template-columns: repeat(3, 1fr);
    gap: 0;
    border: 1px solid var(--line);
  }

  .feature-grid--pilot .feature-grid__item {
    padding: 1.75rem 1.5rem;
    border-bottom: none;
    border-top: none;
  }

  .feature-grid--pilot .feature-grid__item:not(:last-child) {
    border-right: 1px solid var(--line);
  }

  .feature-grid--pilot .feature-grid__item:first-child {
    border-top: none;
  }
}

.pilot-step__head {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  margin-bottom: 1.1rem;
}

.pilot-step__phase {
  font-family: var(--font-display);
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
}

.pilot-step__label {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
}

.pilot-step__list {
  margin: 0;
  padding-left: 1.1rem;
  font-size: 0.92rem;
  color: var(--muted);
}

.pilot-step__list li + li {
  margin-top: 0.55rem;
}

.pilot-step__list li::marker {
  color: var(--accent-2);
}

/* —— Touchpoints —— */
.section--touchpoints {
  background:
    radial-gradient(ellipse 75% 55% at 20% 100%, rgba(62, 224, 197, 0.07), transparent 50%),
    var(--bg);
  border-block: 1px solid var(--line);
}

.touchpoints {
  margin-top: 0.5rem;
}

.touchpoints__tabs {
  display: flex;
  flex-wrap: nowrap;
  gap: 0.25rem;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  margin: 0 0 1.75rem;
  padding-bottom: 0.15rem;
  border-bottom: 1px solid var(--line);
}

.touchpoints__tabs::-webkit-scrollbar {
  display: none;
}

.touchpoints__tab {
  flex: 0 0 auto;
  margin: 0;
  padding: 0.85rem 1rem;
  border: none;
  border-bottom: 2px solid transparent;
  background: transparent;
  color: var(--muted);
  font-family: var(--font-body);
  font-size: 0.92rem;
  font-weight: 500;
  line-height: 1.3;
  white-space: nowrap;
  cursor: pointer;
  transition: color 0.2s ease, border-color 0.25s ease;
}

.touchpoints__tab:hover {
  color: var(--text);
}

.touchpoints__tab.is-active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.touchpoints__tab:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 0.2rem;
}

.touchpoints__panels {
  min-height: 3.5rem;
}

.touchpoints__panel {
  opacity: 0;
  transform: translateY(0.4rem);
  transition: opacity 0.25s ease, transform 0.25s ease;
}

.touchpoints__panel.is-active {
  opacity: 1;
  transform: translateY(0);
}

.touchpoints__panel[hidden] {
  display: none !important;
}

.touchpoints__desc {
  margin: 0;
  max-width: 38rem;
  font-size: clamp(0.98rem, 2vw, 1.05rem);
  color: var(--muted);
}

.touchpoints__note {
  margin: 2.25rem 0 0;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
  max-width: 38rem;
  font-size: 0.95rem;
  color: var(--muted);
}

@media (min-width: 860px) {
  .touchpoints__tabs {
    flex-wrap: wrap;
    overflow-x: visible;
    gap: 0.35rem 1.25rem;
  }
}

/* —— Flow stepper —— */
.section--flow {
  background:
    radial-gradient(ellipse 70% 50% at 50% 100%, rgba(79, 140, 255, 0.07), transparent 50%),
    var(--bg);
  border-block: 1px solid var(--line);
}

.flow {
  --flow-progress: 0.2;
  margin-top: 0.5rem;
}

.flow__steps {
  position: relative;
  margin-bottom: 2rem;
}

.flow__line {
  position: absolute;
  top: 1.15rem;
  left: 10%;
  right: 10%;
  height: 2px;
  background: var(--line);
  pointer-events: none;
}

.flow__line-fill {
  display: block;
  height: 100%;
  width: calc(var(--flow-progress) * 100%);
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  box-shadow: 0 0 12px rgba(62, 224, 197, 0.35);
  transition: width 0.35s ease;
}

.flow__step-list {
  position: relative;
  z-index: 1;
  display: flex;
  justify-content: space-between;
  gap: 0.5rem;
  list-style: none;
  margin: 0;
  padding: 0;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

.flow__step-list::-webkit-scrollbar {
  display: none;
}

.flow__step-item {
  flex: 1 1 0;
  min-width: 4.5rem;
  display: flex;
  justify-content: center;
}

.flow__step {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.55rem;
  margin: 0;
  padding: 0;
  border: none;
  background: transparent;
  cursor: pointer;
  font-family: var(--font-body);
  text-align: center;
}

.flow__step-num {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.3rem;
  height: 2.3rem;
  border-radius: 50%;
  border: 2px solid rgba(139, 155, 180, 0.45);
  background: var(--bg-elevated);
  font-family: var(--font-display);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--muted);
  transition: border-color 0.25s ease, color 0.25s ease, box-shadow 0.25s ease, background-color 0.25s ease;
}

.flow__step-label {
  font-size: 0.78rem;
  font-weight: 500;
  line-height: 1.25;
  color: var(--muted);
  white-space: nowrap;
  transition: color 0.25s ease;
}

.flow__step.is-active .flow__step-num {
  border-color: var(--accent);
  color: var(--accent);
  background: rgba(62, 224, 197, 0.1);
  box-shadow:
    0 0 0 3px rgba(62, 224, 197, 0.12),
    0 0 18px rgba(62, 224, 197, 0.35);
}

.flow__step.is-active .flow__step-label {
  color: var(--text);
}

.flow__step:hover .flow__step-num {
  border-color: rgba(62, 224, 197, 0.55);
}

.flow__step:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
  border-radius: 0.35rem;
}

.flow__panels {
  min-height: 8rem;
}

.flow__panel {
  opacity: 0;
  transform: translateY(0.4rem);
  transition: opacity 0.25s ease, transform 0.25s ease;
}

.flow__panel.is-active {
  opacity: 1;
  transform: translateY(0);
}

.flow__panel[hidden] {
  display: none !important;
}

.flow__panel-title {
  margin: 0 0 0.65rem;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
}

.flow__panel-desc {
  margin: 0 0 0.85rem;
  max-width: 40rem;
  font-size: clamp(0.98rem, 2vw, 1.05rem);
  color: var(--muted);
}

.flow__panel-demo {
  margin: 0;
  padding: 0.85rem 1rem;
  border-left: 2px solid var(--accent);
  background: rgba(13, 21, 34, 0.65);
  max-width: 40rem;
  font-size: 0.9rem;
  color: rgba(232, 238, 248, 0.82);
}

.flow__note {
  margin: 2.25rem 0 0;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
  max-width: 38rem;
  font-size: 0.95rem;
  color: var(--muted);
}

@media (max-width: 640px) {
  /* Vertical stepper on small screens (design §5) */
  .flow__steps {
    padding-left: 0.25rem;
  }

  .flow__line {
    top: 1.15rem;
    bottom: 1.15rem;
    left: calc(1.15rem - 1px);
    right: auto;
    width: 2px;
    height: auto;
  }

  .flow__line-fill {
    width: 100%;
    height: calc(var(--flow-progress) * 100%);
    background: linear-gradient(180deg, var(--accent), var(--accent-2));
    transition: height 0.35s ease;
  }

  .flow__step-list {
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 0;
    overflow-x: visible;
    overflow-y: visible;
  }

  .flow__step-item {
    flex: 0 0 auto;
    min-width: 0;
    justify-content: flex-start;
  }

  .flow__step {
    flex-direction: row;
    align-items: center;
    gap: 0.85rem;
    width: 100%;
    padding: 0.65rem 0;
    text-align: left;
  }

  .flow__step-label {
    white-space: normal;
  }
}

/* —— Demo form —— */
.section--demo {
  background:
    radial-gradient(ellipse 65% 45% at 50% 0%, rgba(62, 224, 197, 0.08), transparent 55%),
    var(--bg);
  border-top: 1px solid var(--line);
}

.demo-form {
  max-width: 32rem;
  margin-top: 0.5rem;
}

.demo-form__field + .demo-form__field {
  margin-top: 1.25rem;
}

.demo-form__label {
  display: block;
  margin-bottom: 0.45rem;
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--text);
}

.demo-form__optional {
  font-weight: 400;
  color: var(--muted);
}

.demo-form__input {
  display: block;
  width: 100%;
  padding: 0.75rem 0.9rem;
  border: 1px solid rgba(139, 155, 180, 0.35);
  border-radius: 0.35rem;
  background: var(--bg-elevated);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 0.95rem;
  line-height: 1.45;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.demo-form__textarea {
  min-height: 6.5rem;
  resize: vertical;
}

.demo-form__input::placeholder {
  color: rgba(139, 155, 180, 0.65);
}

.demo-form__input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(62, 224, 197, 0.18);
}

.demo-form__error {
  min-height: 1.25rem;
  margin: 0.35rem 0 0;
  font-size: 0.82rem;
  color: #f0a07a;
}

.demo-form__submit {
  margin-top: 1.75rem;
  width: 100%;
}

@media (min-width: 480px) {
  .demo-form__submit {
    width: auto;
    min-width: 10rem;
  }
}

.demo-success {
  max-width: 32rem;
  padding: 1.5rem 0 0;
  border-top: 1px solid var(--line);
}

.demo-success__title {
  margin: 0 0 0.5rem;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--accent);
}

.demo-success__text {
  margin: 0;
  font-size: 0.95rem;
  color: var(--muted);
}

/* —— Footer —— */
.site-footer {
  padding: 2.5rem 0 3rem;
  border-top: 1px solid var(--line);
  background: var(--bg-elevated);
}

.site-footer__inner {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  text-align: center;
}

.site-footer__inner p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--muted);
}

.site-footer__brand {
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--text) !important;
}

.site-footer a {
  color: var(--accent);
  text-decoration: none;
}

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

.site-footer__copy {
  margin-top: 0.35rem !important;
  font-size: 0.82rem !important;
  color: rgba(139, 155, 180, 0.75) !important;
}