:root {
  --white: #ffffff;
  --black: #000000;
  --grey: #484848;
  --grey-soft: #7a7a7a;
  --line: #dfdfdf;
  --panel-1: #ffffff;
  --panel-2: #ffffff;
  --panel-3: #ffffff;
  --footer-text: rgba(255, 255, 255, 0.84);
  --footer-muted: rgba(255, 255, 255, 0.62);
  --shadow: 0 30px 80px rgba(0, 0, 0, 0.08);
  --ease: 520ms cubic-bezier(0.22, 1, 0.36, 1);
  --header-space: clamp(28px, 5vw, 56px);
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Trebuchet MS", "Segoe UI", sans-serif;
  color: var(--black);
  background: var(--white);
}

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

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

.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;
}

.site-header {
  display: flex;
  justify-content: center;
  align-items: center;
  background: var(--white);
}

.site-header__logo {
  width: min(190px, 41vw);
  height: auto;
  opacity: 0;
  transform: translateY(18px);
  animation: logo-rise 900ms cubic-bezier(0.19, 1, 0.22, 1) forwards;
}

.accordion {
  display: flex;
  width: 100%;
  min-height: clamp(460px, 70vh, 780px);
  background: var(--white);
}

.accordion-panel {
  --panel-bg: var(--panel-1);
  --panel-image: none;
  position: relative;
  flex: 1 1 0;
  min-width: 0;
  overflow: hidden;
  background-color: var(--panel-bg);
  background-image: var(--panel-image);
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
  background-blend-mode: normal;
  transition:
    flex-grow var(--ease),
    transform 320ms ease,
    background-color 320ms ease;
  cursor: pointer;
  outline: none;
}

.accordion-panel[data-index="1"] {
  --panel-bg: var(--panel-2);
  --panel-image: url("images/filtration_bkg.jpg");
}

.accordion-panel[data-index="2"] {
  --panel-bg: var(--panel-3);
  --panel-image: url("images/amantec_bk.jpg");
}

.accordion-panel[data-index="0"] {
  --panel-image: url("images/elv_bkg.jpg");
}

.accordion-panel.is-active {
  flex-grow: 1.65;
}

.accordion-panel:focus-visible {
  z-index: 2;
  box-shadow: inset 0 0 0 2px var(--black);
}

.accordion-panel::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(180deg, rgba(0, 0, 0, 0.5), rgba(0, 0, 0, 0.68)),
    linear-gradient(115deg, rgba(0, 0, 0, 0.06), rgba(0, 0, 0, 0.18));
  transition: background 260ms ease;
}

.accordion-panel.is-active::before,
.accordion-panel:hover::before,
.accordion-panel:focus-within::before {
  background:
    linear-gradient(180deg, rgba(0, 0, 0, 0.4), rgba(0, 0, 0, 0.58)),
    linear-gradient(115deg, rgba(0, 0, 0, 0.04), rgba(0, 0, 0, 0.12));
}

.accordion-panel__inner {
  position: absolute;
  inset: 0;
  z-index: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: clamp(36px, 5vw, 64px) clamp(20px, 3vw, 42px);
  text-align: center;
}

.accordion-panel__logo {
  width: min(76%, 320px);
  height: auto;
  object-fit: contain;
  filter: drop-shadow(0 10px 30px rgba(0, 0, 0, 0.3));
  transform: translateY(28px) scale(0.96);
  opacity: 0;
  animation: panel-rise 780ms cubic-bezier(0.19, 1, 0.22, 1) forwards;
}

.accordion-panel__logo--filtration {
  width: min(82%, 360px);
}

.accordion-panel__logo--amantec {
  width: min(82%, 360px);
}

.accordion-panel__description {
  max-width: 30ch;
  margin: 26px auto 0;
  font-size: 1rem;
  line-height: 1.8;
  color: rgba(255, 255, 255, 0.88);
  opacity: 0.8;
  transform: translateY(18px);
  transition:
    transform var(--ease),
    opacity 280ms ease,
    color 280ms ease;
}

.accordion-panel__link {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-top: 24px;
  padding: 0 0 8px;
  font-size: 0.92rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--white);
  opacity: 0.9;
  transition:
    letter-spacing 260ms ease,
    opacity 260ms ease,
    color 260ms ease;
}

.accordion-panel__link::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 0;
  width: 100%;
  height: 1px;
  background: currentColor;
  transform: translateX(-50%) scaleX(0.65);
  transform-origin: center;
  transition: transform 260ms ease;
}

.accordion-panel.is-active .accordion-panel__description,
.accordion-panel:focus-within .accordion-panel__description {
  opacity: 1;
  transform: translateY(0);
  color: var(--white);
}

.accordion-panel.is-active .accordion-panel__link,
.accordion-panel:focus-within .accordion-panel__link,
.accordion-panel__link:hover,
.accordion-panel__link:focus-visible {
  letter-spacing: 0.24em;
  opacity: 1;
}

.accordion-panel.is-active .accordion-panel__link::after,
.accordion-panel:focus-within .accordion-panel__link::after,
.accordion-panel__link:hover::after,
.accordion-panel__link:focus-visible::after {
  transform: translateX(-50%) scaleX(1);
}

.site-footer {
  width: 100%;
  margin: 0;
  padding: 34px 20px 22px;
  color: var(--white);
  background: var(--black);
}

.site-footer__certificates {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  gap: 18px;
}

.site-footer__certificates img {
  width: 94px;
  height: auto;
  padding: 10px;
  border-radius: 16px;
  background: var(--white);
}

.site-footer__contacts {
  display: flex;
  justify-content: center;
  align-items: stretch;
  flex-wrap: wrap;
  gap: 18px 30px;
  max-width: 1380px;
  margin: 28px auto 0;
}

.contact-item {
  flex: 1 1 240px;
  display: flex;
  align-items: flex-start;
  gap: 14px;
  max-width: 320px;
  color: var(--footer-text);
  transition:
    transform 240ms ease,
    color 240ms ease;
}

.contact-item:hover,
.contact-item:focus-visible {
  color: var(--white);
  transform: translateY(-2px);
}

.contact-item__icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: 0 0 42px;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.08);
}

.contact-item__icon svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

.contact-item__text {
  display: grid;
  gap: 4px;
}

.contact-item__label {
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--footer-muted);
}

.contact-item__value {
  font-size: 0.95rem;
  line-height: 1.6;
}

.contact-item__value a {
  color: inherit;
  transition: opacity 220ms ease;
}

.contact-item__value a:hover,
.contact-item__value a:focus-visible {
  opacity: 0.7;
}

.site-footer__copyright {
  margin: 28px 0 0;
  font-size: 0.9rem;
  text-align: center;
  color: var(--footer-muted);
}

.site-footer__copyright a {
  color: var(--white);
  transition: opacity 220ms ease;
}

.site-footer__copyright a:hover,
.site-footer__copyright a:focus-visible {
  opacity: 0.7;
}

@keyframes logo-rise {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes panel-rise {
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

@media (hover: hover) and (pointer: fine) {
  .accordion:hover .accordion-panel {
    flex-grow: 0.94;
  }

  .accordion:hover .accordion-panel.is-active {
    flex-grow: 1.95;
  }
}

@media (max-width: 1080px) {
  .accordion {
    min-height: 620px;
  }

  .accordion-panel.is-active {
    flex-grow: 1.45;
  }
}

@media (max-width: 860px) {
  .accordion {
    flex-direction: column;
    min-height: auto;
  }

  .accordion-panel,
  .accordion-panel.is-active {
    flex-grow: 1;
  }

  .accordion-panel {
    min-height: 220px;
    transition:
      min-height var(--ease),
      background-color 320ms ease;
  }

  .accordion-panel.is-active {
    min-height: 360px;
  }

  .accordion-panel__inner {
    padding: 34px 20px;
  }

  .accordion-panel__description {
    max-width: 36ch;
    margin-top: 0;
    opacity: 0;
    max-height: 0;
    overflow: hidden;
  }

  .accordion-panel.is-active .accordion-panel__description,
  .accordion-panel:focus-within .accordion-panel__description {
    max-height: 180px;
    opacity: 1;
    margin-top: 20px;
  }

  .accordion-panel__link {
    opacity: 0;
    max-height: 0;
    overflow: hidden;
    margin-top: 0;
  }

  .accordion-panel.is-active .accordion-panel__link,
  .accordion-panel:focus-within .accordion-panel__link {
    opacity: 1;
    max-height: 60px;
    margin-top: 20px;
  }

  .site-footer {
    padding-inline: 16px;
  }
}

@media (max-width: 560px) {
  .site-header {
    padding-inline: 16px;
  }

  .site-header__logo {
    width: min(145px, 52vw);
  }

  .accordion-panel__logo {
    width: min(88%, 280px);
  }

  .site-footer__certificates img {
    width: 84px;
  }

  .contact-item {
    max-width: 100%;
  }
}

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

  *,
  *::before,
  *::after {
    animation: none !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0ms !important;
  }
}