:root {
  color-scheme: light;
  --paper: #e8e2d2;
  --ink: #26343a;
  --muted-ink: rgba(38, 52, 58, .64);
  --hairline: rgba(38, 52, 58, .18);
  --soft-line: rgba(255, 255, 255, .26);
  --color-a: #dfe7cd;
  --color-b: #a8c6a1;
  --color-c: #6f8f72;
  --accent: #6f8f72;
  --light-x: 34%;
  --light-y: 24%;
  --light-alpha: .48;
  --section-progress: 0;
  --space-1: clamp(.5rem, .42rem + .35vw, .75rem);
  --space-2: clamp(.85rem, .72rem + .55vw, 1.25rem);
  --space-3: clamp(1.25rem, 1rem + 1vw, 2rem);
  --space-4: clamp(2rem, 1.45rem + 2.1vw, 3.7rem);
  --space-5: clamp(3rem, 2.1rem + 3.6vw, 6rem);
  --serif: "Songti SC", "Noto Serif CJK SC", "Source Han Serif SC", "STSong", serif;
  --sans: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", sans-serif;
  --ease: cubic-bezier(.2, .78, .22, 1);
  --ease-soft: cubic-bezier(.33, 1, .68, 1);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 8vh;
  scroll-snap-type: y proximity;
  background: var(--paper);
}

body {
  min-height: 100vh;
  margin: 0;
  overflow-x: hidden;
  color: var(--ink);
  font-family: var(--sans);
  background:
    radial-gradient(circle at var(--light-x) var(--light-y), rgba(255, 249, 224, var(--light-alpha)), transparent 35vw),
    linear-gradient(132deg, var(--color-a) 0%, var(--color-b) 48%, var(--color-c) 100%);
  transition: background 900ms var(--ease-soft), color 900ms var(--ease-soft);
}

body::before,
body::after {
  position: fixed;
  inset: 0;
  z-index: 0;
  content: "";
  pointer-events: none;
}

body::before {
  background:
    linear-gradient(90deg, rgba(255, 255, 255, .28), transparent 18%, transparent 82%, rgba(25, 26, 24, .11)),
    radial-gradient(circle at 12% 82%, rgba(255, 255, 255, .18), transparent 24rem);
  mix-blend-mode: soft-light;
}

body::after {
  background-image:
    linear-gradient(rgba(29, 38, 34, .035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(29, 38, 34, .025) 1px, transparent 1px);
  background-size: 58px 58px;
  opacity: .3;
  mask-image: linear-gradient(90deg, transparent, #000 14%, #000 86%, transparent);
}

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

button {
  font: inherit;
}

#atmosphere,
.paper-texture,
.light-wash {
  position: fixed;
  inset: 0;
  pointer-events: none;
}

#atmosphere {
  z-index: 1;
  mix-blend-mode: screen;
}

.paper-texture {
  z-index: 2;
  background-image: url("assets/paper-grain.png");
  background-size: 900px 600px;
  opacity: .28;
  mix-blend-mode: multiply;
}

.light-wash {
  z-index: 3;
  background:
    radial-gradient(circle at calc(var(--light-x) + 12%) calc(var(--light-y) + 8%), rgba(255, 255, 255, .22), transparent 22rem),
    linear-gradient(180deg, rgba(255, 255, 255, .2), transparent 40%, rgba(20, 26, 24, .12));
  opacity: .72;
}

.site-rail {
  position: fixed;
  top: var(--space-3);
  left: clamp(1rem, 2.8vw, 3rem);
  z-index: 12;
  width: min(18rem, 30vw);
  display: grid;
  gap: var(--space-4);
}

.brand {
  display: inline-grid;
  width: max-content;
  gap: .28rem;
  color: rgba(23, 32, 32, .82);
}

.brand span {
  font-family: var(--serif);
  font-size: clamp(1.65rem, 1.25rem + 1.35vw, 2.55rem);
  letter-spacing: .08em;
}

.brand small {
  font-size: .68rem;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--muted-ink);
}

.today-card {
  width: min(17rem, 100%);
  padding-left: 1.1rem;
  border-left: 1px solid var(--hairline);
  transition: opacity 460ms var(--ease), transform 620ms var(--ease);
}

.today-card.is-changing {
  opacity: .42;
  transform: translate3d(0, .45rem, 0);
}

.eyebrow,
.opening p,
.term-kicker,
.term-en,
.term-date {
  margin: 0;
  color: var(--muted-ink);
  font-family: var(--sans);
  font-size: .72rem;
  font-weight: 500;
  letter-spacing: .18em;
  text-transform: uppercase;
}

.today-card h1 {
  margin: .65rem 0 .6rem;
  color: var(--ink);
  font-family: var(--serif);
  font-size: clamp(2.25rem, 1.2rem + 4vw, 5.1rem);
  font-weight: 500;
  line-height: .92;
  letter-spacing: .04em;
}

.today-card p:last-child {
  max-width: 13.5rem;
  margin: 0;
  color: rgba(35, 44, 42, .76);
  font-family: var(--serif);
  font-size: clamp(.9rem, .82rem + .28vw, 1.05rem);
  line-height: 1.86;
}

.term-nav {
  position: fixed;
  top: 50%;
  right: clamp(.8rem, 2vw, 2.6rem);
  z-index: 12;
  width: 8.4rem;
  transform: translateY(-50%);
}

.term-nav ol {
  position: relative;
  display: grid;
  gap: .12rem;
  margin: 0;
  padding: .6rem 0 .6rem 1.1rem;
  list-style: none;
}

.term-nav ol::before {
  position: absolute;
  top: .8rem;
  bottom: .8rem;
  left: .35rem;
  width: 1px;
  content: "";
  background: linear-gradient(180deg, transparent, var(--hairline), transparent);
}

.term-nav button {
  position: relative;
  display: grid;
  grid-template-columns: 1.25rem 1fr;
  align-items: center;
  width: 100%;
  min-height: 1.25rem;
  padding: 0;
  border: 0;
  color: rgba(34, 44, 42, .48);
  background: transparent;
  cursor: pointer;
  text-align: left;
  transition: color 420ms var(--ease), transform 420ms var(--ease);
}

.term-nav button::before {
  width: .34rem;
  height: .34rem;
  border: 1px solid currentColor;
  border-radius: 999px;
  content: "";
  background: rgba(255, 255, 255, .2);
  transition: transform 420ms var(--ease), background 420ms var(--ease), border-color 420ms var(--ease);
}

.term-nav span {
  font-family: var(--serif);
  font-size: .78rem;
  letter-spacing: .12em;
  white-space: nowrap;
}

.term-nav small {
  display: none;
}

.term-nav button:hover,
.term-nav button.is-active,
.term-nav button.is-today {
  color: var(--ink);
  transform: translateX(-.18rem);
}

.term-nav button.is-active::before,
.term-nav button.is-today::before {
  border-color: var(--accent);
  background: var(--accent);
  transform: scale(1.55);
}

.term-nav button.is-today span::after {
  margin-left: .35rem;
  content: "今";
  color: var(--accent);
  font-family: var(--sans);
  font-size: .62rem;
  letter-spacing: .04em;
}

.year-scroll {
  position: relative;
  z-index: 5;
}

.opening {
  min-height: 42vh;
  display: grid;
  align-content: end;
  width: min(66rem, calc(100vw - 3rem));
  margin: 0 auto;
  padding: var(--space-5) clamp(1rem, 4vw, 5rem) var(--space-4);
  color: rgba(31, 42, 39, .72);
  scroll-snap-align: start;
}

.opening h2 {
  max-width: 11em;
  margin: .45rem 0 0;
  font-family: var(--serif);
  font-size: clamp(2.2rem, 1.12rem + 4.4vw, 6.4rem);
  font-weight: 500;
  line-height: .98;
  letter-spacing: .04em;
}

.term-sections {
  position: relative;
}

.term-section {
  --section-progress: 0;
  min-height: 104vh;
  display: grid;
  align-items: center;
  padding: var(--space-5) clamp(1.25rem, 7vw, 8rem);
  scroll-margin-top: 4vh;
  scroll-snap-align: start;
  opacity: calc(.24 + var(--section-progress) * .76);
  transition: opacity 520ms var(--ease);
}

.term-inner {
  width: min(62rem, 100%);
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(8rem, 14rem) minmax(0, 1fr);
  gap: clamp(2.2rem, 6vw, 7rem);
  align-items: center;
}

.term-title-wrap {
  min-height: 30rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.term-name {
  position: relative;
  margin: 0;
  writing-mode: vertical-rl;
  color: rgba(28, 38, 36, .9);
  font-family: var(--serif);
  font-size: clamp(5.4rem, 4rem + 5.2vw, 11rem);
  font-weight: 500;
  line-height: .88;
  letter-spacing: .15em;
  text-shadow: 0 1px 0 rgba(255, 255, 255, .16);
  cursor: default;
}

.term-name::after {
  position: absolute;
  top: .08em;
  bottom: .1em;
  left: -.22em;
  width: 1px;
  content: "";
  background: linear-gradient(180deg, transparent, var(--accent), transparent);
  transform: scaleY(.08);
  transform-origin: top;
  opacity: .42;
  transition: transform 640ms var(--ease), opacity 640ms var(--ease);
}

.term-section:hover .term-name::after,
.term-section.is-active .term-name::after {
  transform: scaleY(1);
  opacity: .86;
}

.term-content {
  position: relative;
  padding: clamp(1.4rem, 2.4vw, 2.6rem) 0;
}

.term-content::before {
  position: absolute;
  top: 0;
  right: 0;
  left: -2rem;
  height: 1px;
  content: "";
  background: linear-gradient(90deg, var(--hairline), transparent);
}

.term-content::after {
  position: absolute;
  right: 8%;
  bottom: 6%;
  width: clamp(5rem, 16vw, 14rem);
  height: clamp(5rem, 16vw, 14rem);
  border-radius: 999px;
  content: "";
  background: color-mix(in srgb, var(--accent) 26%, transparent);
  filter: blur(42px);
  opacity: .32;
  transform: translate3d(0, calc((1 - var(--section-progress)) * 1.6rem), 0);
}

.term-meta {
  display: flex;
  flex-wrap: wrap;
  gap: .65rem 1rem;
  align-items: center;
  margin-bottom: var(--space-3);
}

.term-kicker {
  color: var(--accent);
}

.term-date {
  color: rgba(32, 42, 39, .5);
}

.term-en {
  color: rgba(32, 42, 39, .52);
  letter-spacing: .12em;
}

.term-copy {
  max-width: 31rem;
  margin: 0;
  color: rgba(28, 39, 36, .82);
  font-family: var(--serif);
  font-size: clamp(1.3rem, 1rem + 1.05vw, 2.15rem);
  font-weight: 400;
  line-height: 1.72;
  letter-spacing: .03em;
}

.phenology {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(.85rem, 1.6vw, 1.4rem);
  max-width: 38rem;
  margin: var(--space-4) 0 0;
  padding: 0;
  list-style: none;
}

.phenology li {
  position: relative;
  min-height: 8rem;
  padding: 1.1rem 1rem;
  border-top: 1px solid transparent;
  color: rgba(27, 38, 35, .72);
  font-family: var(--serif);
  font-size: clamp(1rem, .94rem + .24vw, 1.16rem);
  line-height: 1.62;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, .14), transparent),
    color-mix(in srgb, var(--paper) 14%, transparent);
  backdrop-filter: blur(2px);
  opacity: calc(max(0, min(1, (var(--section-progress) - var(--stagger) * .09) * 1.45)));
  transform: translate3d(0, calc((1 - max(0, min(1, (var(--section-progress) - var(--stagger) * .09) * 1.45))) * 2.8rem), 0);
  transition:
    opacity 720ms var(--ease),
    transform 860ms var(--ease),
    color 420ms var(--ease),
    background 420ms var(--ease);
  transition-delay: calc(var(--stagger) * 90ms);
  will-change: transform, opacity;
}

.phenology li::before {
  position: absolute;
  top: 0;
  left: 0;
  width: calc(max(0, min(1, (var(--section-progress) - var(--stagger) * .09) * 1.55)) * 100%);
  height: 1px;
  content: "";
  background: linear-gradient(90deg, var(--accent), var(--hairline), transparent);
  opacity: calc(.22 + var(--section-progress) * .46);
  transition: width 920ms var(--ease), opacity 420ms var(--ease), background 420ms var(--ease);
  transition-delay: calc(var(--stagger) * 90ms);
}

.phenology li:hover {
  color: rgba(24, 34, 31, .9);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, .22), transparent),
    color-mix(in srgb, var(--accent) 8%, transparent);
  transform: translate3d(0, calc((1 - max(0, min(1, (var(--section-progress) - var(--stagger) * .09) * 1.45))) * 2.8rem - .28rem), 0);
}

.phenology li:hover::before {
  opacity: .86;
  background: linear-gradient(90deg, var(--accent), color-mix(in srgb, var(--accent) 36%, transparent), transparent);
}

.phenology span {
  display: block;
  margin-bottom: .65rem;
  color: var(--accent);
  font-family: var(--sans);
  font-size: .66rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  transition: color 420ms var(--ease), transform 420ms var(--ease);
}

.phenology li:hover span {
  transform: translate3d(0, -.08rem, 0);
}

.season-mark {
  position: absolute;
  right: 0;
  bottom: -1.2rem;
  color: rgba(31, 42, 39, .2);
  font-family: var(--sans);
  font-size: clamp(3.5rem, 9vw, 9rem);
  font-weight: 300;
  line-height: 1;
  letter-spacing: .05em;
  text-transform: uppercase;
  pointer-events: none;
}

.term-section .term-title-wrap,
.term-section .term-content {
  will-change: transform, opacity;
}

.term-section .term-title-wrap {
  opacity: calc(.08 + var(--section-progress) * .92);
  transform:
    translate3d(0, calc((1 - var(--section-progress)) * 5.6rem), 0)
    scale(calc(.97 + var(--section-progress) * .03));
  transition: opacity 760ms var(--ease), transform 980ms var(--ease);
}

.term-section .term-content {
  opacity: calc(.04 + var(--section-progress) * .96);
  transform: translate3d(0, calc((1 - var(--section-progress)) * 7.2rem), 0);
  transition: opacity 820ms var(--ease), transform 1120ms var(--ease);
}

.term-section.is-active {
  opacity: 1;
}

.term-section.is-today .term-name {
  color: var(--ink);
}

.term-section.is-today .term-kicker::after {
  content: " / 今日";
}

@media (max-width: 1020px) {
  .site-rail {
    width: min(16rem, 34vw);
  }

  .term-nav {
    width: 6.7rem;
  }

  .term-nav span {
    font-size: .72rem;
  }

  .term-inner {
    grid-template-columns: minmax(6rem, 10rem) minmax(0, 1fr);
    gap: clamp(1.5rem, 4vw, 3rem);
  }
}

@media (max-width: 760px) {
  html {
    scroll-padding-top: 7rem;
  }

  body {
    background:
      radial-gradient(circle at var(--light-x) var(--light-y), rgba(255, 249, 224, calc(var(--light-alpha) * .75)), transparent 72vw),
      linear-gradient(145deg, var(--color-a), var(--color-b) 54%, var(--color-c));
  }

  .paper-texture {
    background-size: 640px 426px;
    opacity: .24;
  }

  .site-rail {
    position: fixed;
    top: 0;
    right: 0;
    left: 0;
    width: auto;
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    padding: .9rem 1rem .75rem;
    background: linear-gradient(180deg, rgba(237, 232, 216, .76), rgba(237, 232, 216, .2), transparent);
    backdrop-filter: blur(10px);
  }

  .brand span {
    font-size: 1.55rem;
  }

  .brand small {
    font-size: .58rem;
  }

  .today-card {
    max-width: 13.5rem;
    padding-left: .8rem;
  }

  .today-card h1 {
    margin: .15rem 0 .18rem;
    font-size: 1.55rem;
    line-height: 1;
  }

  .today-card p:last-child {
    display: -webkit-box;
    overflow: hidden;
    font-size: .76rem;
    line-height: 1.45;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
  }

  .term-nav {
    top: auto;
    right: 0;
    bottom: 0;
    left: 0;
    width: auto;
    transform: none;
    background: linear-gradient(0deg, rgba(232, 226, 210, .9), rgba(232, 226, 210, .5), transparent);
    backdrop-filter: blur(12px);
  }

  .term-nav ol {
    display: flex;
    overflow-x: auto;
    gap: .45rem;
    padding: .75rem 1rem 1rem;
    scroll-snap-type: x mandatory;
  }

  .term-nav ol::before {
    display: none;
  }

  .term-nav li {
    scroll-snap-align: center;
  }

  .term-nav button {
    grid-template-columns: auto;
    justify-items: center;
    min-width: 3.6rem;
    gap: .32rem;
    color: rgba(34, 44, 42, .56);
    text-align: center;
    transform: none;
  }

  .term-nav button::before {
    width: .4rem;
    height: .4rem;
  }

  .term-nav button:hover,
  .term-nav button.is-active,
  .term-nav button.is-today {
    transform: translateY(-.1rem);
  }

  .term-nav span {
    font-size: .68rem;
  }

  .opening {
    min-height: 34vh;
    padding-top: 8rem;
  }

  .term-section {
    min-height: 96vh;
    padding: 7.5rem 1.15rem 7rem;
  }

  .term-inner {
    display: block;
    width: min(32rem, 100%);
  }

  .term-title-wrap {
    min-height: auto;
    display: block;
    margin-bottom: var(--space-3);
  }

  .term-name {
    writing-mode: horizontal-tb;
    font-size: clamp(4.1rem, 19vw, 6.6rem);
    line-height: 1;
    letter-spacing: .08em;
  }

  .term-name::after {
    top: auto;
    right: .1em;
    bottom: -.12em;
    left: 0;
    width: auto;
    height: 1px;
    transform: scaleX(.12);
    transform-origin: left;
  }

  .term-section:hover .term-name::after,
  .term-section.is-active .term-name::after {
    transform: scaleX(.86);
  }

  .term-content::before {
    left: 0;
  }

  .term-copy {
    font-size: clamp(1.18rem, 4.4vw, 1.55rem);
    line-height: 1.78;
  }

  .phenology {
    grid-template-columns: 1fr;
    gap: .8rem;
    margin-top: var(--space-3);
  }

  .phenology li {
    min-height: auto;
    padding: .9rem 0 .9rem 1rem;
    border-top: 0;
    border-left: 1px solid transparent;
    background: transparent;
    transform: translate3d(0, calc((1 - max(0, min(1, (var(--section-progress) - var(--stagger) * .09) * 1.45))) * 1.65rem), 0);
  }

  .phenology li::before {
    width: 1px;
    height: calc(max(0, min(1, (var(--section-progress) - var(--stagger) * .09) * 1.55)) * 100%);
    background: linear-gradient(180deg, var(--accent), var(--hairline), transparent);
  }

  .phenology li:hover {
    transform: translate3d(0, calc((1 - max(0, min(1, (var(--section-progress) - var(--stagger) * .09) * 1.45))) * 1.65rem - .18rem), 0);
  }

  .season-mark {
    right: .2rem;
    bottom: -2.8rem;
    font-size: 4rem;
  }
}

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

  *,
  *::before,
  *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: .01ms !important;
  }

  #atmosphere {
    display: none;
  }

  .term-section,
  .term-section .term-title-wrap,
  .term-section .term-content,
  .phenology li {
    opacity: 1;
    transform: none;
  }

  .phenology li::before {
    width: 100%;
    height: 1px;
  }
}