:root {
  --black: #080a09;
  --black-soft: #0f1210;
  --ink: #11130f;
  --paper: #f2f0e9;
  --paper-bright: #fbfaf5;
  --white: #fffefa;
  --orange: #ff5c00;
  --orange-bright: #ff6a00;
  --green: #93b77b;
  --green-dark: #466b35;
  --line-dark: rgba(255, 255, 255, 0.17);
  --line-light: rgba(8, 10, 9, 0.18);
  --page: min(1180px, calc(100% - 72px));
  --header-height: 84px;
  --radius: 3px;
  --transition: 220ms ease;
  color-scheme: dark;
  font-family: Inter, "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-synthesis: none;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 20px);
}

body {
  margin: 0;
  overflow-x: hidden;
  background: var(--black);
  color: var(--white);
  font-size: 17px;
  line-height: 1.58;
  -webkit-font-smoothing: antialiased;
}

body.menu-open {
  overflow: hidden;
}

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

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

button,
summary,
a {
  -webkit-tap-highlight-color: transparent;
}

:focus-visible {
  outline: 3px solid var(--orange-bright);
  outline-offset: 5px;
}

.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: fixed;
  z-index: 1000;
  top: 16px;
  left: 16px;
  padding: 10px 16px;
  transform: translateY(-180%);
  background: var(--orange);
  color: var(--white);
  font-weight: 700;
  transition: transform var(--transition);
}

.skip-link:focus {
  transform: translateY(0);
}

.page-shell {
  width: var(--page);
  margin-inline: auto;
}

.section {
  position: relative;
  padding: clamp(90px, 10vw, 150px) 0;
}

.section--dark {
  background: var(--black);
  color: var(--white);
}

.section--light {
  background: var(--paper);
  color: var(--ink);
  color-scheme: light;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1,
h2,
h3 {
  letter-spacing: -0.045em;
  line-height: 0.99;
}

h1 {
  max-width: 700px;
  margin-bottom: 28px;
  font-size: clamp(3.2rem, 6.3vw, 6rem);
  font-weight: 590;
}

h2 {
  margin-bottom: 30px;
  font-size: clamp(2.6rem, 5vw, 4.8rem);
  font-weight: 560;
}

h3 {
  font-size: clamp(1.55rem, 2.5vw, 2.25rem);
  font-weight: 560;
}

.eyebrow {
  margin-bottom: 19px;
  color: var(--orange-bright);
  font-size: 0.76rem;
  font-weight: 760;
  letter-spacing: 0.15em;
  line-height: 1.2;
  text-transform: uppercase;
}

.eyebrow--green {
  color: var(--green);
}

.section-intro {
  font-size: clamp(1.18rem, 1.7vw, 1.45rem);
  line-height: 1.45;
}

.button {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  padding: 12px 22px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-size: 0.93rem;
  font-weight: 690;
  line-height: 1;
  transition:
    color var(--transition),
    background var(--transition),
    border-color var(--transition),
    transform var(--transition);
}

.button:hover {
  transform: translateY(-2px);
}

.button--primary {
  background: var(--orange);
  color: var(--white);
}

.button--primary:hover {
  background: #ff7625;
}

.button--outline {
  border-color: var(--orange);
}

.button--outline:hover {
  background: var(--orange);
}

.text-link {
  display: inline-flex;
  gap: 8px;
  align-items: center;
  border-bottom: 1px solid var(--orange);
  color: var(--orange-bright);
  font-weight: 680;
  transition: border-color var(--transition), color var(--transition);
}

.text-link:hover {
  border-color: var(--white);
  color: var(--white);
}

.text-link--dark:hover {
  border-color: var(--ink);
  color: var(--ink);
}

.site-header {
  position: fixed;
  z-index: 100;
  top: 0;
  left: 0;
  display: flex;
  width: 100%;
  height: var(--header-height);
  align-items: center;
  justify-content: space-between;
  padding: 0 max(36px, calc((100% - 1180px) / 2));
  border-bottom: 1px solid transparent;
  transition: background var(--transition), border-color var(--transition), height var(--transition);
}

.site-header.is-scrolled {
  height: 70px;
  border-bottom-color: var(--line-dark);
  background: rgba(8, 10, 9, 0.92);
  backdrop-filter: blur(18px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 1.22rem;
  font-weight: 730;
  letter-spacing: 0.06em;
}

.brand__mark {
  position: relative;
  display: block;
  width: 31px;
  height: 39px;
  overflow: hidden;
  flex: 0 0 auto;
  background: var(--black);
}

.brand__mark img {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 57px;
  max-width: none;
  transform: translate(-50%, -50%);
}

.primary-nav {
  display: flex;
  align-items: center;
  gap: clamp(24px, 3vw, 48px);
  font-size: 0.92rem;
}

.primary-nav > a:not(.button) {
  position: relative;
}

.primary-nav > a:not(.button)::after {
  position: absolute;
  right: 0;
  bottom: -8px;
  left: 0;
  height: 1px;
  background: var(--orange);
  content: "";
  transform: scaleX(0);
  transform-origin: right;
  transition: transform var(--transition);
}

.primary-nav > a:not(.button):hover::after,
.primary-nav > a.is-active:not(.button)::after {
  transform: scaleX(1);
  transform-origin: left;
}

.menu-toggle {
  display: none;
}

.hero {
  position: relative;
  display: grid;
  min-height: min(920px, 100svh);
  align-content: end;
  overflow: hidden;
  padding: calc(var(--header-height) + 86px) 0 44px;
  background: var(--black);
}

.hero__media,
.hero__overlay {
  position: absolute;
  inset: 0;
}

.hero__media {
  background-image: url("assets/hero-heater.jpg");
  background-position: 68% center;
  background-size: cover;
  transform: scale(1.015);
}

.hero__overlay {
  background:
    linear-gradient(90deg, rgba(0, 0, 0, 0.97) 0%, rgba(0, 0, 0, 0.83) 33%, rgba(0, 0, 0, 0.18) 72%, rgba(0, 0, 0, 0.34) 100%),
    linear-gradient(0deg, rgba(0, 0, 0, 0.73) 0%, transparent 42%);
}

.hero__content,
.hero__stats {
  position: relative;
  z-index: 1;
}

.hero__content {
  margin-bottom: clamp(60px, 8vh, 105px);
}

.hero__lead {
  max-width: 540px;
  margin-bottom: 34px;
  font-size: clamp(1.12rem, 1.6vw, 1.32rem);
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 22px 34px;
  align-items: center;
}

.hero__stats {
  display: grid;
  grid-template-columns: 1fr 1fr 1.35fr;
  border: 1px solid rgba(255, 112, 27, 0.52);
  background: rgba(4, 5, 4, 0.52);
  backdrop-filter: blur(10px);
}

.stat {
  display: grid;
  min-height: 84px;
  grid-template-columns: auto 1fr;
  gap: 18px;
  align-items: center;
  padding: 15px 28px;
  border-right: 1px solid rgba(255, 112, 27, 0.45);
}

.stat:last-child {
  border-right: 0;
}

.stat strong {
  color: var(--orange-bright);
  font-size: clamp(1.35rem, 2vw, 2rem);
  font-weight: 580;
  letter-spacing: -0.03em;
  line-height: 1;
}

.stat span {
  color: rgba(255, 255, 255, 0.75);
  font-size: 0.72rem;
  font-weight: 680;
  letter-spacing: 0.08em;
  line-height: 1.25;
  text-transform: uppercase;
}

.stat--wide strong {
  font-size: 0.95rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.principle {
  padding-block: clamp(80px, 8vw, 125px);
}

.principle__grid {
  display: grid;
  grid-template-columns: minmax(300px, 0.85fr) 1.15fr;
  gap: clamp(70px, 10vw, 170px);
  align-items: start;
}

.principle h2 {
  max-width: 500px;
}

.principle__grid > div > p {
  max-width: 670px;
}

.process-line {
  display: flex;
  margin: 52px 0 0;
  padding: 0;
  color: var(--orange);
  font-size: 0.75rem;
  font-weight: 720;
  letter-spacing: 0.08em;
  list-style: none;
  text-transform: uppercase;
}

.process-line li {
  display: flex;
  align-items: center;
}

.process-line li:not(:last-child)::after {
  width: clamp(34px, 5vw, 76px);
  height: 1px;
  margin-inline: 12px;
  background: var(--orange);
  content: "";
}

.technology {
  border-top: 1px solid var(--line-dark);
}

.technology__grid {
  display: grid;
  grid-template-columns: 1fr 0.95fr;
  gap: clamp(60px, 9vw, 135px);
  align-items: center;
}

.technology__image {
  position: relative;
  min-height: 650px;
  margin: 0;
  overflow: hidden;
  border: 1px solid rgba(147, 183, 123, 0.68);
  border-radius: 270px 270px 0 0;
  background: #000;
}

.technology__image img {
  width: 100%;
  height: 100%;
  min-height: 650px;
  object-fit: cover;
  object-position: center;
}

.technology__content h2 {
  max-width: 650px;
}

.technology__content > p:not(.eyebrow) {
  max-width: 650px;
  color: rgba(255, 255, 255, 0.75);
}

.feature-list {
  margin: 50px 0 0;
  padding: 0;
  list-style: none;
}

.feature-list li {
  display: grid;
  grid-template-columns: 1fr 1.45fr;
  gap: 24px;
  padding: 16px 0;
  border-top: 1px solid var(--line-dark);
}

.feature-list li::before {
  display: block;
  width: 30px;
  height: 1px;
  align-self: center;
  background: var(--green);
  content: "";
  grid-column: 1 / -1;
  grid-row: 1;
}

.feature-list span,
.feature-list small {
  grid-row: 2;
}

.feature-list span {
  font-size: 1.05rem;
  font-weight: 620;
}

.feature-list small {
  color: rgba(255, 255, 255, 0.58);
  font-size: 0.86rem;
}

.technology__media-grid {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: clamp(60px, 9vw, 135px);
  margin-top: clamp(100px, 12vw, 180px);
  padding-top: clamp(70px, 8vw, 120px);
  border-top: 1px solid var(--line-dark);
}

.technology__media-grid h3 {
  max-width: 460px;
  font-size: clamp(2rem, 4vw, 3.8rem);
}

.media-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.media-list li {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 25px;
  padding: 24px 0;
  border-top: 1px solid var(--line-dark);
}

.media-list li:last-child {
  border-bottom: 1px solid var(--line-dark);
}

.media-list strong {
  font-weight: 610;
}

.media-list span {
  color: rgba(255, 255, 255, 0.62);
}

.combustion-note {
  margin-top: clamp(70px, 8vw, 120px);
  padding: 35px 0 0 50%;
  border-top: 1px solid var(--orange);
}

.combustion-note p {
  max-width: 650px;
  color: rgba(255, 255, 255, 0.72);
  font-size: 1.05rem;
}

.applications {
  border-top: 1px solid var(--line-dark);
  padding-top: clamp(95px, 11vw, 165px);
}

.applications__heading {
  display: grid;
  grid-template-columns: 1.4fr 0.6fr;
  gap: 60px;
  align-items: end;
  margin-bottom: 70px;
}

.applications__heading .eyebrow,
.applications__heading h2 {
  grid-column: 1;
}

.applications__heading h2 {
  max-width: 820px;
  margin-bottom: 0;
}

.applications__heading > p:last-child {
  grid-column: 2;
  grid-row: 2;
  margin-bottom: 0;
  color: rgba(255, 255, 255, 0.62);
}

.applications__grid {
  display: grid;
  grid-template-columns: 1.25fr 0.75fr;
  gap: clamp(45px, 8vw, 120px);
  align-items: start;
}

.application-list {
  border-top: 1px solid var(--line-dark);
}

.application-item {
  border-bottom: 1px solid var(--line-dark);
}

.application-item summary {
  display: grid;
  padding: 24px 40px 24px 0;
  cursor: pointer;
  font-size: clamp(1.35rem, 2.4vw, 2rem);
  font-weight: 430;
  grid-template-columns: 70px 1fr;
  list-style: none;
  transition: color var(--transition);
}

.application-item summary::-webkit-details-marker {
  display: none;
}

.application-item summary::after {
  position: absolute;
  right: 5px;
  color: var(--green);
  content: "+";
  font-size: 1.5rem;
  font-weight: 300;
}

.application-item[open] summary::after {
  content: "−";
}

.application-item summary {
  position: relative;
}

.application-item summary:hover {
  color: var(--orange-bright);
}

.application-item summary span {
  color: var(--green);
  font-variant-numeric: tabular-nums;
}

.application-item > p {
  max-width: 710px;
  margin: 0;
  padding: 0 30px 28px 70px;
  color: rgba(255, 255, 255, 0.67);
}

.application-item .equation {
  padding-top: 4px;
  color: var(--orange-bright);
  font-size: 1.18rem;
  font-weight: 600;
}

.applications__image {
  position: sticky;
  top: 105px;
  margin: 0;
}

.applications__image::before {
  position: absolute;
  z-index: -1;
  inset: -18px 18px 18px -18px;
  border: 1px solid rgba(147, 183, 123, 0.45);
  content: "";
}

.applications__image img {
  width: 100%;
  max-height: 680px;
  object-fit: cover;
}

.applications__image figcaption {
  margin-top: 15px;
  color: rgba(255, 255, 255, 0.5);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.research__grid {
  display: grid;
  grid-template-columns: 0.8fr 1.05fr 0.65fr;
  gap: clamp(50px, 7vw, 100px);
  align-items: start;
}

.research h2 {
  font-size: clamp(2.6rem, 4.8vw, 4.3rem);
}

.publication {
  padding-left: 42px;
  border-left: 1px solid var(--orange);
}

.publication__type {
  display: block;
  margin-bottom: 24px;
  color: var(--green-dark);
  font-size: 0.75rem;
  font-weight: 740;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.publication h3 {
  line-height: 1.12;
}

.publication p {
  color: rgba(17, 19, 15, 0.67);
}

.patent-note {
  padding: 26px;
  border: 1px solid var(--orange);
}

.patent-note span {
  display: inline-block;
  margin-bottom: 15px;
  color: var(--orange);
  font-size: 0.72rem;
  font-weight: 750;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.patent-note p {
  margin-bottom: 0;
  font-size: 0.92rem;
}

.about {
  display: grid;
  min-height: 680px;
  align-items: end;
  overflow: hidden;
}

.about__image,
.about__overlay {
  position: absolute;
  inset: 0;
}

.about__image {
  background-image: url("assets/development-system.jpg");
  background-position: center;
  background-size: cover;
  transform: scale(1.02);
}

.about__overlay {
  background:
    linear-gradient(90deg, rgba(0, 0, 0, 0.97) 0%, rgba(0, 0, 0, 0.52) 65%, rgba(0, 0, 0, 0.32) 100%),
    linear-gradient(0deg, rgba(0, 0, 0, 0.8), transparent 60%);
}

.about__content {
  position: relative;
  z-index: 1;
}

.about h2 {
  max-width: 930px;
}

.about__copy {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 50px;
  max-width: 950px;
  color: rgba(255, 255, 255, 0.75);
}

.contact {
  border-top: 1px solid var(--line-dark);
}

.contact__grid {
  display: grid;
  grid-template-columns: 1fr 0.8fr;
  gap: clamp(70px, 10vw, 170px);
  align-items: end;
}

.contact h2 {
  max-width: 710px;
}

.contact__content > p {
  margin-bottom: 32px;
  color: rgba(255, 255, 255, 0.68);
}

.contact__content .button {
  margin: 0 25px 24px 0;
}

.contact__email {
  display: inline-block;
  margin-bottom: 24px;
  color: var(--green);
  font-size: 1.05rem;
}

.site-footer {
  border-top: 1px solid var(--line-dark);
  background: var(--black);
  padding: 45px 0;
  color: rgba(255, 255, 255, 0.52);
  font-size: 0.78rem;
}

.site-footer__grid {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 55px;
  align-items: center;
}

.brand--footer {
  color: var(--white);
  font-size: 0.95rem;
}

.site-footer address {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 25px;
  font-style: normal;
}

.site-footer p {
  margin-bottom: 0;
}

.js .reveal {
  opacity: 0;
  transform: translateY(28px);
  transition:
    opacity 700ms ease,
    transform 700ms cubic-bezier(0.2, 0.65, 0.3, 1);
}

.js .reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 980px) {
  :root {
    --page: min(100% - 46px, 760px);
  }

  .site-header {
    padding-inline: 23px;
  }

  .menu-toggle {
    position: relative;
    z-index: 102;
    display: grid;
    width: 46px;
    height: 46px;
    padding: 12px;
    border: 1px solid var(--line-dark);
    background: rgba(0, 0, 0, 0.4);
    cursor: pointer;
    place-content: center;
  }

  .menu-toggle span:not(.sr-only) {
    display: block;
    width: 22px;
    height: 1px;
    margin: 4px 0;
    background: var(--white);
    transition: transform var(--transition);
  }

  .menu-toggle[aria-expanded="true"] span:nth-of-type(2) {
    transform: translateY(4.5px) rotate(45deg);
  }

  .menu-toggle[aria-expanded="true"] span:nth-of-type(3) {
    transform: translateY(-4.5px) rotate(-45deg);
  }

  .primary-nav {
    position: fixed;
    z-index: 101;
    inset: 0;
    display: flex;
    visibility: hidden;
    flex-direction: column;
    align-items: flex-start;
    justify-content: center;
    padding: 100px 11vw;
    background: rgba(8, 10, 9, 0.98);
    font-size: clamp(1.8rem, 7vw, 3.2rem);
    opacity: 0;
    transform: translateY(-15px);
    transition: opacity var(--transition), transform var(--transition), visibility var(--transition);
  }

  .primary-nav.is-open {
    visibility: visible;
    opacity: 1;
    transform: translateY(0);
  }

  .primary-nav .nav-contact {
    margin-top: 20px;
    font-size: 1rem;
  }

  .hero {
    min-height: 900px;
  }

  .hero__media {
    background-position: 62% center;
  }

  .hero__overlay {
    background: linear-gradient(90deg, rgba(0, 0, 0, 0.94) 0%, rgba(0, 0, 0, 0.55) 65%, rgba(0, 0, 0, 0.3) 100%);
  }

  .hero__stats {
    grid-template-columns: 1fr 1fr;
  }

  .stat:nth-child(2) {
    border-right: 0;
  }

  .stat--wide {
    grid-column: 1 / -1;
    border-top: 1px solid rgba(255, 112, 27, 0.45);
  }

  .principle__grid,
  .technology__grid,
  .technology__media-grid,
  .applications__heading,
  .applications__grid,
  .research__grid,
  .contact__grid {
    grid-template-columns: 1fr;
  }

  .applications__heading .eyebrow,
  .applications__heading h2,
  .applications__heading > p:last-child {
    grid-column: 1;
    grid-row: auto;
  }

  .applications__heading > p:last-child {
    max-width: 600px;
  }

  .technology__image {
    width: min(100%, 620px);
    min-height: 600px;
  }

  .technology__image img {
    min-height: 600px;
  }

  .technology__media-grid {
    gap: 30px;
  }

  .combustion-note {
    padding-left: 30%;
  }

  .applications__image {
    position: relative;
    top: auto;
    width: min(72%, 480px);
    margin: 40px auto 0;
  }

  .research__grid {
    gap: 55px;
  }

  .publication {
    padding-left: 30px;
  }

  .patent-note {
    max-width: 440px;
  }

  .site-footer__grid {
    grid-template-columns: 1fr;
    gap: 25px;
  }
}

@media (max-width: 640px) {
  :root {
    --page: calc(100% - 36px);
    --header-height: 70px;
  }

  body {
    font-size: 16px;
  }

  .brand {
    font-size: 1rem;
  }

  .hero {
    min-height: 850px;
    padding-bottom: 18px;
  }

  .hero__media {
    background-position: 60% center;
  }

  .hero__overlay {
    background:
      linear-gradient(90deg, rgba(0, 0, 0, 0.96) 0%, rgba(0, 0, 0, 0.64) 72%, rgba(0, 0, 0, 0.42) 100%),
      linear-gradient(0deg, rgba(0, 0, 0, 0.7), transparent 60%);
  }

  .hero__content {
    margin-bottom: 52px;
  }

  .hero__stats {
    grid-template-columns: 1fr;
  }

  .stat {
    min-height: 72px;
    border-right: 0;
    border-bottom: 1px solid rgba(255, 112, 27, 0.45);
  }

  .stat:nth-child(2) {
    border-bottom: 1px solid rgba(255, 112, 27, 0.45);
  }

  .stat:last-child {
    border-bottom: 0;
  }

  .stat--wide {
    grid-column: auto;
    border-top: 0;
  }

  .process-line {
    flex-direction: column;
    gap: 15px;
  }

  .process-line li:not(:last-child)::after {
    display: none;
  }

  .technology__image,
  .technology__image img {
    min-height: 430px;
  }

  .technology__image {
    border-radius: 220px 220px 0 0;
  }

  .feature-list li,
  .media-list li {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .feature-list small,
  .feature-list span {
    grid-row: auto;
  }

  .combustion-note {
    padding-left: 0;
  }

  .application-item summary {
    grid-template-columns: 48px 1fr;
    padding-right: 32px;
  }

  .application-item > p {
    padding-left: 48px;
  }

  .applications__image {
    width: calc(100% - 20px);
  }

  .about {
    min-height: 850px;
  }

  .about__image {
    background-position: 56% center;
  }

  .about__copy {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .contact__content .button {
    width: 100%;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}