:root {
  color-scheme: light;
  --paper: #f4efe6;
  --paper-light: #fbf8f2;
  --card: #fffdf8;
  --ink: #20332e;
  --ink-soft: #66726c;
  --line: rgba(32, 51, 46, 0.14);
  --vermilion: #bb5b45;
  --vermilion-deep: #984632;
  --accent: #617e70;
  --accent-deep: #496759;
  --shadow: 0 18px 55px rgba(56, 48, 37, 0.09);
  --radius-large: 1.75rem;
  --radius-medium: 1.15rem;
  --content-width: 58rem;
  --page-gutter: clamp(1.15rem, 4vw, 3rem);
  --serif: "Iowan Old Style", "Palatino Linotype", "Yu Mincho",
    "Hiragino Mincho ProN", Georgia, serif;
  --sans: "Avenir Next", Avenir, "Hiragino Kaku Gothic ProN",
    "Yu Gothic", "Noto Sans JP", system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
}

body {
  min-width: 20rem;
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 8% 2%, rgba(187, 91, 69, 0.09), transparent 24rem),
    radial-gradient(circle at 96% 38%, rgba(97, 126, 112, 0.14), transparent 28rem),
    var(--paper);
  font-family: var(--sans);
  line-height: 1.6;
  text-rendering: optimizeLegibility;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

main {
  padding-block: clamp(1.5rem, 4vw, 3rem) clamp(7rem, 12vw, 10rem);
}

.back-link {
  display: inline-flex;
  gap: 0.55rem;
  align-items: center;
  margin-bottom: clamp(2rem, 4.5vw, 3.25rem);
  color: var(--ink-soft);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-decoration: none;
  transition: color 200ms ease;
}

.back-link__arrow {
  color: var(--accent-deep);
  font-size: 1.05rem;
  transition: transform 200ms ease;
}

.back-link:focus-visible,
.source-link:focus-visible,
.control-button:focus-visible {
  outline: 3px solid rgba(97, 126, 112, 0.48);
  outline-offset: 0.25rem;
}

.reading-header {
  position: relative;
  overflow: hidden;
  padding: clamp(1.75rem, 5vw, 3.25rem);
  border: 1px solid var(--line);
  border-radius: var(--radius-large);
  background:
    radial-gradient(circle at 92% 8%, rgba(97, 126, 112, 0.15), transparent 13rem),
    var(--card);
  box-shadow: var(--shadow);
  isolation: isolate;
}

.reading-header::before {
  position: absolute;
  inset: 0;
  border-top: 0.34rem solid var(--accent);
  border-radius: inherit;
  content: "";
  pointer-events: none;
}

.reading-header__glyph {
  position: absolute;
  z-index: -1;
  top: -2rem;
  right: 0.3rem;
  color: rgba(73, 103, 89, 0.075);
  font-family: var(--serif);
  font-size: clamp(10rem, 25vw, 17rem);
  line-height: 1;
  pointer-events: none;
  user-select: none;
}

.level-badge {
  display: inline-grid;
  min-width: 2.65rem;
  min-height: 2rem;
  padding-inline: 0.65rem;
  place-items: center;
  border-radius: 999px;
  color: #fff;
  background: var(--accent);
  letter-spacing: 0.08em;
}

h1 {
  position: relative;
  z-index: 1;
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(2.15rem, 6.5vw, 4.2rem);
  font-weight: 500;
  letter-spacing: -0.045em;
  line-height: 1.3;
}

.reading-header__english {
  position: relative;
  z-index: 1;
  margin: 0.55rem 0 0;
  color: var(--accent-deep);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.reading-header__intro {
  position: relative;
  z-index: 1;
  max-width: 38rem;
  margin: 1.5rem 0 0;
  color: var(--ink-soft);
  font-size: clamp(0.98rem, 1.7vw, 1.08rem);
}

.rules-section {
  margin-top: 0.9rem;
}

.rules-list {
  display: grid;
  gap: 0.9rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.rule-card {
  position: relative;
  display: block;
  min-height: 10.75rem;
  overflow: hidden;
  padding: clamp(1.2rem, 3vw, 1.65rem)
    clamp(13rem, 34%, 17rem) clamp(1.2rem, 3vw, 1.65rem)
    clamp(1.2rem, 3vw, 1.65rem);
  border: 1px solid var(--line);
  border-left-width: 0.28rem;
  border-radius: var(--radius-medium);
  background: var(--card);
  box-shadow: 0 10px 30px rgba(56, 48, 37, 0.055);
  isolation: isolate;
}

.rule-card::before,
.rule-card__image {
  position: absolute;
  inset: 0 0 0 auto;
  width: clamp(15rem, 40%, 20rem);
  pointer-events: none;
}

.rule-card__image {
  z-index: 0;
  display: block;
  height: 100%;
  object-fit: cover;
  object-position: center;
}

.rule-card::before {
  z-index: 1;
  background:
    linear-gradient(
      90deg,
      var(--card) 0%,
      rgba(255, 253, 248, 0.96) 15%,
      rgba(255, 253, 248, 0.58) 43%,
      rgba(255, 253, 248, 0.12) 72%,
      transparent 88%
    );
  content: "";
}

.rule-card > :not(.rule-card__image) {
  position: relative;
  z-index: 2;
}

.rule-card--do {
  border-left-color: var(--accent);
  background:
    linear-gradient(110deg, rgba(97, 126, 112, 0.04), transparent 45%),
    var(--card);
}

.rule-card--dont {
  border-left-color: var(--vermilion);
  background:
    linear-gradient(110deg, rgba(187, 91, 69, 0.035), transparent 45%),
    var(--card);
}

.rule-content {
  min-width: 0;
}

.source-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  justify-content: flex-end;
  margin-top: 1.5rem;
}

.source-link:hover {
  color: var(--accent-deep);
}

.grammar-section {
  margin-top: clamp(3rem, 7vw, 5rem);
}

.grammar-card {
  overflow: hidden;
  border: 1px solid var(--line);
  border-top: 0.34rem solid var(--vermilion);
  border-radius: var(--radius-large);
  background: var(--card);
  box-shadow: var(--shadow);
}

.grammar-header {
  padding: clamp(1.5rem, 4vw, 2.5rem);
  border-bottom: 1px solid var(--line);
  background:
    linear-gradient(145deg, rgba(187, 91, 69, 0.08), transparent 62%),
    var(--card);
}

.grammar-kicker {
  margin: 0 0 0.4rem;
  color: var(--vermilion-deep);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.grammar-header h2 {
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(1.85rem, 4.5vw, 2.75rem);
  font-weight: 500;
  letter-spacing: -0.03em;
}

.grammar-meaning {
  margin: 0.65rem 0 0;
  color: var(--ink-soft);
  font-size: 1rem;
}

.grammar-meaning strong {
  color: var(--ink);
}

.grammar-body {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
  gap: clamp(1.5rem, 4vw, 3rem);
  padding: clamp(1.5rem, 4vw, 2.5rem);
}

.grammar-explanation {
  margin: 0;
  color: var(--ink-soft);
  font-size: 1rem;
}

.grammar-formula {
  margin-top: 1.25rem;
  padding: 1rem 1.1rem;
  border: 1px solid rgba(97, 126, 112, 0.2);
  border-radius: 0.9rem;
  background: rgba(97, 126, 112, 0.065);
}

.grammar-formula__label {
  display: block;
  margin-bottom: 0.35rem;
  color: var(--accent-deep);
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.grammar-formula__pattern {
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(1.15rem, 2.5vw, 1.4rem);
  line-height: 1.7;
}

.grammar-formula__plus {
  margin-inline: 0.35rem;
  color: var(--vermilion-deep);
  font-family: var(--sans);
  font-weight: 800;
}

.grammar-note {
  margin: 1rem 0 0;
  color: var(--ink-soft);
  font-size: 0.9rem;
}

.grammar-note strong {
  color: var(--ink);
}

.grammar-examples h3 {
  margin: 0 0 0.75rem;
  color: var(--ink-soft);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.grammar-example-list {
  display: grid;
  gap: 0;
  margin: 0;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 0.9rem;
  list-style: none;
}

.grammar-example {
  display: grid;
  grid-template-columns: minmax(5rem, 0.55fr) auto minmax(10rem, 1.45fr);
  gap: 0.65rem;
  align-items: center;
  padding: 0.8rem 1rem;
  border-bottom: 1px solid var(--line);
}

.grammar-example:last-child {
  border-bottom: 0;
}

.grammar-example__verb,
.grammar-example__result {
  font-family: var(--serif);
  font-size: 1.05rem;
}

.grammar-example__verb {
  color: var(--accent-deep);
}

.grammar-example__arrow {
  color: var(--vermilion-deep);
  font-weight: 800;
}

.grammar-example__result {
  font-weight: 600;
}

.control-button:hover:not(:disabled) {
  background: rgba(32, 51, 46, 0.07);
}

.control-button:disabled {
  cursor: not-allowed;
  opacity: 0.58;
}

.control-button__state {
  min-width: 2.35rem;
  padding: 0.2rem 0.42rem;
  border-radius: 999px;
  color: #fff;
  background: var(--accent);
  font-size: 0.62rem;
  letter-spacing: 0.08em;
  text-align: center;
}

@media screen and (min-width: 50.0625rem) and (hover: hover) and (pointer: fine) {
  html {
    font-size: 80%;
  }
}

@media (max-width: 38rem) {
  .rule-card {
    min-height: 12rem;
    padding: 1.25rem clamp(4.5rem, 22vw, 7rem) 1.25rem 1.25rem;
  }

  .rule-card::before,
  .rule-card__image {
    width: 58%;
  }

  .rule-card__image {
    object-position: 72% center;
  }

  .rule-card::before {
    background:
      linear-gradient(
        90deg,
        var(--card) 0%,
        rgba(255, 253, 248, 0.96) 24%,
        rgba(255, 253, 248, 0.76) 53%,
        rgba(255, 253, 248, 0.36) 78%,
        rgba(255, 253, 248, 0.14) 100%
      );
  }

  .grammar-body {
    grid-template-columns: 1fr;
  }

  .grammar-example {
    grid-template-columns: minmax(4.5rem, 0.55fr) auto minmax(0, 1.45fr);
  }
}

@media (max-width: 31rem) {
  .reading-header {
    border-radius: 1.35rem;
  }

  .js .reading-controls {
    right: 0.75rem;
    bottom: 0.75rem;
    left: 0.75rem;
    flex-wrap: wrap;
    justify-content: center;
    border-radius: var(--radius-medium);
  }

  .control-button {
    flex: 1;
    justify-content: center;
    padding-inline: 0.55rem;
  }
}

@media print {
  html,
  body {
    background: #fff;
  }

  main {
    padding-block: 0;
  }

  .back-link,
  .reading-controls,
  .source-row {
    display: none !important;
  }

  .reading-header,
  .rule-card {
    box-shadow: none;
    break-inside: avoid;
  }

  .rule-card {
    min-height: 0;
    padding: 1.25rem;
  }

  .rule-card::before,
  .rule-card__image {
    display: none;
  }

  .grammar-card {
    box-shadow: none;
    break-inside: avoid;
  }
}

.no-break {
  white-space: nowrap;
}