:root {
  --sustainability-paper: #f5f5f1;
  --sustainability-ink: #151515;
  --sustainability-body: #656560;
  --sustainability-quiet: #8e8e93;
}

* { box-sizing: border-box; }

html {
  background: var(--sustainability-paper);
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--sustainability-paper);
  color: var(--sustainability-ink);
  font-family: "SF Pro Display", "SF Pro Text", -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Helvetica Neue", Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, p { margin: 0; }

.page-return {
  position: fixed;
  z-index: 20;
  top: 30px;
  right: clamp(24px, 4vw, 60px);
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border: 1px solid rgba(21, 21, 21, 0.12);
  border-radius: 50%;
  background: rgba(245, 245, 241, 0.8);
  color: var(--sustainability-ink);
  transition: transform 300ms cubic-bezier(0.22, 1, 0.36, 1), background-color 300ms ease;
}

.page-return::before,
.page-return::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 14px;
  height: 1px;
  background: currentColor;
}

.page-return::before { transform: translate(-50%, -50%) rotate(45deg); }
.page-return::after { transform: translate(-50%, -50%) rotate(-45deg); }
.page-return:hover { background: #fff; transform: scale(1.04); }
.page-return:focus-visible { outline: 2px solid rgba(21, 21, 21, .55); outline-offset: 3px; }

.sustainability-page { min-height: 100vh; }

.sustainability-story {
  height: 600vh;
  position: relative;
}

.sustainability-stage {
  position: sticky;
  top: 0;
  height: 100vh;
  overflow: clip;
  isolation: isolate;
}

.sustainability-stage::before {
  content: "";
  position: absolute;
  z-index: -1;
  inset: 0;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.15), transparent 32%), var(--sustainability-paper);
}

.sustainability-heading {
  position: absolute;
  z-index: 2;
  top: var(--title-top, 36vh);
  left: 50%;
  width: min(100% - 48px, 1040px);
  text-align: center;
  transform: translateX(-50%) scale(var(--title-scale, 1));
  transform-origin: top center;
  will-change: top, transform;
}

.sustainability-heading h1 {
  font-size: clamp(48px, 7.5vw, 96px);
  font-weight: 700;
  line-height: 0.98;
  letter-spacing: -0.082em;
}

.sustainability-heading p {
  margin-top: clamp(10px, 1.2vw, 15px);
  color: var(--sustainability-quiet);
  font-size: clamp(13px, 1.35vw, 18px);
  font-weight: 500;
  letter-spacing: -0.02em;
  opacity: var(--title-subtitle-opacity, 1);
}

.sustainability-scroll-prompt {
  position: absolute;
  z-index: 2;
  bottom: clamp(36px, 5vh, 58px);
  left: 50%;
  margin: 0;
  color: var(--sustainability-quiet);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.08em;
  line-height: 1;
  opacity: var(--scroll-prompt-opacity, 0.72);
  transform: translateX(-50%) translateY(var(--scroll-prompt-y, 0px));
  pointer-events: none;
  will-change: opacity, transform;
}

.sustainability-reading {
  position: absolute;
  top: 52%;
  left: 50%;
  width: min(100% - 48px, 680px);
  height: min(42vh, 390px);
  transform: translate(-50%, -50%);
}

.sustainability-item {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  pointer-events: none;
  opacity: var(--item-opacity, 0);
  transform: translateY(var(--item-y, 30px)) scale(var(--item-scale, 0.985));
  transform-origin: center center;
  will-change: opacity, transform;
}

.sustainability-item h2 {
  font-size: clamp(31px, 3.5vw, 46px);
  font-weight: 600;
  line-height: 1.12;
  letter-spacing: -0.07em;
}

.sustainability-item p {
  max-width: 620px;
  margin-top: clamp(21px, 2.4vw, 30px);
  color: var(--sustainability-body);
  font-size: clamp(17px, 1.55vw, 21px);
  font-weight: 400;
  line-height: 1.76;
  letter-spacing: -0.035em;
}

.sustainability-progress {
  position: absolute;
  z-index: 3;
  top: 50%;
  right: clamp(20px, 4vw, 60px);
  display: flex;
  align-items: center;
  gap: 14px;
  color: #b8b8b8;
  font-family: "SF Mono", "SFMono-Regular", ui-monospace, Menlo, monospace;
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.04em;
  line-height: 1;
  opacity: var(--progress-opacity, 0);
  transform: translateY(-50%);
  pointer-events: none;
  transition: opacity 180ms ease;
}

.sustainability-progress-line {
  position: relative;
  width: 2px;
  height: 80px;
  overflow: hidden;
  background: rgba(213, 213, 213, 0.3);
}

.sustainability-progress-line i {
  position: absolute;
  right: 0;
  bottom: 0;
  width: 100%;
  height: var(--progress-fill, 0%);
  background: rgba(129, 129, 124, 0.55);
}

.sustainability-ending {
  position: absolute;
  top: 56%;
  left: 50%;
  width: min(100% - 48px, 920px);
  text-align: center;
  opacity: var(--ending-opacity, 0);
  transform: translate(-50%, calc(-50% + var(--ending-y, 24px))) scale(var(--ending-scale, 0.985));
  transform-origin: center;
  will-change: opacity, transform;
}

.sustainability-ending p {
  color: var(--sustainability-ink);
  font-size: clamp(29px, 4vw, 52px);
  font-weight: 600;
  line-height: 1.23;
  letter-spacing: -0.075em;
}

.sustainability-ending p + p { margin-top: clamp(28px, 3vw, 40px); }

.sustainability-ending small {
  display: block;
  max-width: 520px;
  margin: 140px auto 0;
  color: var(--sustainability-quiet);
  font-size: 12px;
  font-weight: 400;
  line-height: 1.7;
  letter-spacing: -0.015em;
}

@media (max-width: 720px) {
  .sustainability-heading { width: calc(100% - 40px); }
  .sustainability-heading h1 { letter-spacing: -0.09em; }
  .sustainability-reading { width: calc(100% - 72px); height: min(48vh, 390px); }
  .sustainability-scroll-prompt { bottom: 34px; font-size: 10px; }
  .sustainability-item h2 { font-size: clamp(28px, 8.8vw, 38px); }
  .sustainability-item p { font-size: 17px; line-height: 1.72; }
  .sustainability-progress { right: 18px; gap: 10px; }
  .sustainability-progress-line { height: 68px; }
  .sustainability-ending { width: calc(100% - 44px); }
  .sustainability-ending p { font-size: clamp(26px, 7.7vw, 36px); line-height: 1.26; }
  .sustainability-ending small { margin-top: 100px; font-size: 11px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .sustainability-progress { transition: none; }
}