/**
 * Layout — page shell and chapter containers
 */

.app {
  min-height: 100vh;
}

.app-loading {
  position: fixed;
  inset: 0;
  z-index: var(--loading-z-index);
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-bg);
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

.app-loading.is-leaving {
  pointer-events: none;
}

.app-loading.is-hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.app-loading__text {
  margin: 0;
  font-family: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", sans-serif;
  font-size: clamp(0.85rem, 1.95vw, 1.02rem);
  font-weight: 100;
  font-synthesis: none;
  letter-spacing: 0.12em;
  text-indent: 0.12em;
  color: rgba(42, 42, 42, 0.86);
  -webkit-font-smoothing: antialiased;
  opacity: 1;
}

.app-loading__line {
  display: inline-block;
  will-change: transform, opacity;
}

.app-loading__phrase {
  letter-spacing: inherit;
}

.app-loading__dots {
  display: inline-block;
  min-width: 1.05em;
  text-align: left;
  letter-spacing: 0;
  text-indent: 0;
}

.app-loading__dot {
  opacity: 0;
}

.app-loading__dot:nth-child(1) {
  animation: app-loading-dot-1 2.1s ease-in-out infinite;
}

.app-loading__dot:nth-child(2) {
  animation: app-loading-dot-2 2.1s ease-in-out infinite;
}

.app-loading__dot:nth-child(3) {
  animation: app-loading-dot-3 2.1s ease-in-out infinite;
}

@keyframes app-loading-dot-1 {
  0%,
  100% {
    opacity: 0;
  }

  8%,
  76% {
    opacity: 1;
  }

  92% {
    opacity: 0;
  }
}

@keyframes app-loading-dot-2 {
  0%,
  26% {
    opacity: 0;
  }

  34%,
  76% {
    opacity: 1;
  }

  92% {
    opacity: 0;
  }
}

@keyframes app-loading-dot-3 {
  0%,
  52% {
    opacity: 0;
  }

  60%,
  76% {
    opacity: 1;
  }

  92% {
    opacity: 0;
  }
}

.app-loading.is-preparing .app-loading__dot {
  animation: none;
  opacity: 1;
}

.app-loading.is-preparing .app-loading__line {
  animation: app-loading-push-in 0.64s cubic-bezier(0.42, 0, 0.18, 1) 0.12s forwards;
}

@keyframes app-loading-push-in {
  from {
    transform: translate3d(0, 0, 0);
  }

  to {
    transform: translate3d(-1.35em, 0, 0);
  }
}

.app-loading.is-leaving .app-loading__text {
  animation: app-loading-text-out 0.72s ease forwards;
}

.app-loading.is-leaving {
  animation: app-loading-backdrop-out 0.58s ease 0.38s forwards;
}

@keyframes app-loading-text-out {
  from {
    opacity: 1;
  }

  to {
    opacity: 0;
    visibility: hidden;
  }
}

@keyframes app-loading-backdrop-out {
  from {
    opacity: 1;
  }

  to {
    opacity: 0;
    visibility: hidden;
  }
}

.main {
  width: 100%;
  background-color: var(--color-bg);
}

.chapter {
  position: relative;
  min-height: var(--section-min-height);
  padding: var(--space-xl) var(--space-md);
}

.chapter[data-chapter-id="01-intro"] {
  background: transparent;
}

/* Hero 之后：正文与雨滴共用同一底色 */
.reading-scene {
  position: relative;
  background: var(--color-bg);
}

.reading-mist {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
  -webkit-mask-image: linear-gradient(to bottom, transparent 0, #000 10vh, #000 calc(100% - 6vh), transparent 100%);
  mask-image: linear-gradient(to bottom, transparent 0, #000 10vh, #000 calc(100% - 6vh), transparent 100%);
}

.reading-entrance {
  position: relative;
  z-index: 1;
  background: var(--color-bg);
  min-height: 160vh;
  min-height: 160dvh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16vh var(--space-md) 14vh;
  text-align: center;
}

.reading-entrance__inner {
  position: relative;
  z-index: 1;
  width: min(42rem, 92vw);
}

.reading-mist__cloud {
  position: absolute;
  transform: translate3d(0, 0, 0);
  will-change: transform, opacity;
  filter: blur(13px);
}

.reading-mist__puff {
  position: absolute;
  background: radial-gradient(
    ellipse at 38% 36%,
    rgba(255, 255, 255, 1) 0%,
    rgba(255, 255, 255, 0.72) 34%,
    rgba(255, 255, 255, 0.18) 62%,
    transparent 76%
  );
}

.reading-mist__cloud--shade {
  filter: blur(16px);
}

.reading-mist__cloud--shade .reading-mist__puff {
  background: radial-gradient(
    ellipse at 42% 40%,
    rgba(186, 194, 204, 0.38) 0%,
    rgba(198, 204, 212, 0.16) 50%,
    transparent 74%
  );
}

.reading-scene > .chapter {
  position: relative;
  z-index: 1;
  background: var(--color-bg);
}

.reading-entrance__title {
  margin: 0;
  font-family: "Noto Serif SC", var(--font-serif);
  font-weight: 300;
  font-synthesis: none;
  font-size: clamp(1.35rem, 2.8vw, 1.85rem);
  letter-spacing: 0.16em;
  text-indent: 0.16em;
  color: rgba(42, 42, 42, 0.86);
  -webkit-font-smoothing: antialiased;
}

.reading-entrance__lead,
.reading-entrance__verse,
.reading-entrance__body {
  margin: 0;
  font-family: "Noto Serif SC", var(--font-serif);
  font-weight: 300;
  font-synthesis: none;
  letter-spacing: 0.08em;
  color: rgba(48, 48, 48, 0.78);
  -webkit-font-smoothing: antialiased;
}

.reading-entrance__lead {
  margin-top: 6.5rem;
  font-size: clamp(1.08rem, 2.15vw, 1.48rem);
  line-height: 1.85;
}

.reading-entrance__verse,
.reading-entrance__body {
  font-size: clamp(0.88rem, 1.55vw, 1.02rem);
  line-height: 2.15;
}

.reading-entrance__verse {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.35em;
  margin-top: 8.5rem;
}

.reading-entrance__body {
  display: flex;
  flex-direction: column;
  gap: 1.65em;
  margin-top: 4.5rem;
  text-align: center;
}

.reading-entrance__body strong,
.reading-prose__inner strong {
  font-weight: 700;
  color: rgba(36, 36, 36, 0.88);
}

.reading-prose {
  position: relative;
  z-index: 1;
  background: var(--color-bg);
  padding: 14vh var(--space-md) 18vh;
  text-align: center;
}

.reading-prose__inner {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  gap: 1.65em;
  width: min(42rem, 92vw);
  margin-inline: auto;
}

.reading-prose__inner p {
  margin: 0;
  font-family: "Noto Serif SC", var(--font-serif);
  font-weight: 300;
  font-synthesis: none;
  font-size: clamp(0.88rem, 1.55vw, 1.02rem);
  line-height: 2.15;
  letter-spacing: 0.08em;
  color: rgba(48, 48, 48, 0.78);
  -webkit-font-smoothing: antialiased;
}

.reading-prose--chapter-start {
  padding-top: 22vh;
}

.reading-prose__inner .reading-entrance__title {
  margin: 5rem 0 0;
}

.reading-prose__inner .reading-entrance__title:first-child {
  margin-top: 0;
}

.reading-prose.is-visible .reading-reveal {
  animation: reading-fade-in var(--reading-fade-duration-body) ease forwards;
}

.reading-entrance__hint {
  margin: 5.2rem 0 0;
  display: flex;
  justify-content: center;
}

.reading-entrance__hint-motion {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.55rem;
}

.reading-entrance__hint-line {
  display: block;
  width: 1px;
  height: 2rem;
  background: linear-gradient(to bottom, transparent, rgba(58, 58, 58, 0.72));
}

.reading-entrance__hint-label {
  font-family: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", sans-serif;
  font-size: clamp(0.72rem, 1.6vw, 0.82rem);
  font-weight: 100;
  font-synthesis: none;
  letter-spacing: 0.32em;
  text-indent: 0.32em;
  color: rgba(58, 58, 58, 0.88);
  -webkit-font-smoothing: antialiased;
}

.reading-entrance__click-hint {
  margin: clamp(0.85rem, 1.8vh, 1.35rem) 0 clamp(0.75rem, 1.6vh, 1.25rem);
  font-family: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", sans-serif;
  font-size: clamp(0.68rem, 1.5vw, 0.78rem);
  font-weight: 100;
  font-synthesis: none;
  letter-spacing: 0.22em;
  text-indent: 0.22em;
  color: rgba(58, 58, 58, 0.55);
  -webkit-font-smoothing: antialiased;
}

.reading-entrance__title,
.reading-entrance__lead,
.reading-entrance__verse span,
.reading-entrance__body p,
.reading-entrance__hint,
.reading-entrance__click-hint,
.reading-reveal {
  opacity: 0;
  transform: translate3d(0, var(--reading-fade-shift), 0);
}

.reading-entrance.is-visible .reading-entrance__title {
  animation: reading-fade-in var(--reading-fade-duration) ease 0.12s forwards;
}

.reading-entrance.is-visible .reading-entrance__lead {
  animation: reading-fade-in var(--reading-fade-duration-body) ease 1.15s forwards;
}

.reading-entrance.is-visible .reading-entrance__verse span:nth-child(1) {
  animation: reading-fade-in var(--reading-fade-duration) ease 2.7s forwards;
}

.reading-entrance.is-visible .reading-entrance__verse span:nth-child(2) {
  animation: reading-fade-in var(--reading-fade-duration) ease calc(2.7s + var(--reading-fade-stagger)) forwards;
}

.reading-entrance.is-visible .reading-entrance__verse span:nth-child(3) {
  animation: reading-fade-in var(--reading-fade-duration) ease calc(2.7s + var(--reading-fade-stagger) * 2) forwards;
}

.reading-entrance.is-visible .reading-entrance__verse span:nth-child(4) {
  animation: reading-fade-in var(--reading-fade-duration) ease calc(2.7s + var(--reading-fade-stagger) * 3) forwards;
}

.reading-entrance.is-visible .reading-entrance__verse span:nth-child(5) {
  animation: reading-fade-in var(--reading-fade-duration) ease calc(2.7s + var(--reading-fade-stagger) * 4) forwards;
}

.reading-entrance.is-visible .reading-entrance__body p:nth-child(1) {
  animation: reading-fade-in var(--reading-fade-duration-body) ease 4.55s forwards;
}

.reading-entrance.is-visible .reading-entrance__body p:nth-child(2) {
  animation: reading-fade-in var(--reading-fade-duration-body) ease 5.15s forwards;
}

.reading-entrance.is-visible .reading-entrance__hint {
  animation: reading-fade-in var(--reading-fade-duration) ease 5.9s forwards;
}

.reading-entrance.is-visible .reading-entrance__click-hint {
  animation: reading-fade-in var(--reading-fade-duration) ease 6.5s forwards;
}

@keyframes reading-fade-in {
  from {
    opacity: 0;
    transform: translate3d(0, var(--reading-fade-shift), 0);
  }

  to {
    opacity: 1;
    transform: translate3d(0, 0, 0);
  }
}

@media (prefers-reduced-motion: no-preference) {
  .reading-entrance.is-visible .reading-entrance__hint-motion {
    animation: reading-entrance-hint-float 3.4s ease-in-out 7.8s infinite;
  }
}

@keyframes reading-entrance-hint-float {
  0%,
  100% {
    opacity: 0.55;
    transform: translateY(0);
  }

  50% {
    opacity: 1;
    transform: translateY(6px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .app-loading.is-preparing .app-loading__line,
  .app-loading.is-leaving,
  .app-loading.is-leaving .app-loading__text,
  .app-loading__dot {
    animation: none;
  }

  .app-loading__dot {
    opacity: 1;
  }

  .reading-entrance__title,
  .reading-entrance__lead,
  .reading-entrance__verse span,
  .reading-entrance__body p,
  .reading-entrance__hint,
  .reading-entrance__click-hint,
  .reading-reveal {
    opacity: 1;
    transform: none;
    animation: none;
  }
}

.chapter__inner {
  max-width: var(--content-max-width);
  margin-inline: auto;
}

.chapter__placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  min-height: 50vh;
  padding: var(--space-2xl) var(--space-md);
  text-align: center;
}

.chapter__placeholder-label {
  font-family: var(--font-serif);
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  letter-spacing: 0.04em;
}

.chapter__placeholder-note {
  font-size: var(--font-size-xs);
  letter-spacing: var(--letter-spacing-wide);
  color: var(--color-text-faint);
}

.app-error {
  max-width: 36rem;
  padding: var(--space-lg);
  text-align: left;
}

.app-error__title {
  font-family: var(--font-serif);
  font-size: var(--font-size-lg);
  margin-bottom: var(--space-md);
  color: var(--color-text);
}

.app-error__detail {
  font-family: ui-monospace, "Cascadia Code", monospace;
  font-size: var(--font-size-xs);
  line-height: var(--line-height-loose);
  color: var(--color-text-muted);
  white-space: pre-wrap;
  word-break: break-word;
  margin: 0;
  padding: var(--space-md);
  background: var(--color-bg-muted);
  border-radius: 4px;
}

.chapter[data-chapter-status="pending"] .chapter__content {
  /* Reserved for future chapter content */
}