:root {
  color-scheme: light;
  --page: #dce1f3;
  --surface: #eef0fa;
  --card: #f8f8ff;
  --ink: #1f2340;
  --ink-soft: #676d91;
  --line: rgba(39, 45, 93, 0.12);
  --accent: #5b4bd1;
  --accent-strong: #4337ad;
  --accent-soft: rgba(91, 75, 209, 0.11);
  --shadow: rgba(30, 35, 86, 0.18);
  --radius-card: 28px;
  --radius-control: 15px;
  --ease: cubic-bezier(.16, 1, .3, 1);
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
}

* {
  box-sizing: border-box;
}

html,
body {
  min-width: 320px;
  min-height: 100%;
  margin: 0;
}

body {
  min-height: 100dvh;
  overflow-x: hidden;
  color: var(--ink);
  background: var(--page);
  -webkit-tap-highlight-color: transparent;
}

button,
a {
  font: inherit;
}

button {
  color: inherit;
}

svg {
  display: block;
  width: 1.25rem;
  height: 1.25rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 8px;
  left: 8px;
  padding: 10px 14px;
  border-radius: 10px;
  color: var(--card);
  background: var(--ink);
  transform: translateY(-160%);
  transition: transform 160ms ease;
}

.skip-link:focus {
  transform: translateY(0);
}

.app-shell {
  position: relative;
  display: grid;
  grid-template-rows: auto auto minmax(0, 1fr) auto;
  width: min(100%, 500px);
  min-height: 100dvh;
  margin: 0 auto;
  padding: max(18px, env(safe-area-inset-top)) 18px max(14px, env(safe-area-inset-bottom));
  overflow: hidden;
  background: var(--surface);
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 54px;
}

.brand {
  display: inline-flex;
  gap: 11px;
  align-items: center;
  color: inherit;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 42px;
  height: 42px;
  border-radius: 14px;
  color: var(--card);
  background: var(--accent);
  box-shadow: 0 8px 24px rgba(91, 75, 209, 0.27);
  place-items: center;
}

.brand-mark svg {
  width: 30px;
  height: 30px;
  stroke-width: 2.1;
}

.brand strong,
.brand small {
  display: block;
}

.brand strong {
  font-size: 17px;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.brand small {
  margin-top: 4px;
  color: var(--ink-soft);
  font-size: 10px;
  letter-spacing: 0.08em;
}

.icon-button,
.favorite-button,
.dialog-close {
  display: grid;
  width: 46px;
  height: 46px;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: rgba(248, 248, 255, 0.58);
  cursor: pointer;
  place-items: center;
}

.info-button svg {
  width: 21px;
  height: 21px;
}

.quick-actions {
  display: flex;
  gap: 9px;
  padding: 16px 0 12px;
}

.action-chip {
  display: inline-flex;
  min-height: 44px;
  padding: 0 14px;
  gap: 8px;
  align-items: center;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--ink-soft);
  background: rgba(248, 248, 255, 0.64);
  font-size: 13px;
  font-weight: 650;
  cursor: pointer;
  transition: color 180ms ease, border-color 180ms ease, background 180ms ease, transform 180ms ease;
}

.action-chip svg {
  width: 17px;
  height: 17px;
}

.action-chip[aria-pressed="true"] {
  border-color: rgba(91, 75, 209, 0.25);
  color: var(--accent-strong);
  background: var(--accent-soft);
}

.count-badge {
  display: grid;
  min-width: 20px;
  height: 20px;
  padding: 0 5px;
  border-radius: 999px;
  color: var(--ink-soft);
  background: rgba(45, 50, 99, 0.08);
  font-size: 10px;
  font-variant-numeric: tabular-nums;
  place-items: center;
}

.main-content {
  display: grid;
  min-height: 0;
  align-content: center;
  padding: 4px 0 10px;
}

.question-card {
  position: relative;
  display: flex;
  min-height: min(590px, calc(100dvh - 244px));
  padding: 22px 22px 18px;
  flex-direction: column;
  border: 1px solid rgba(45, 50, 99, 0.08);
  border-radius: var(--radius-card);
  outline: none;
  background: var(--card);
  box-shadow: 0 24px 60px -34px var(--shadow), 0 2px 6px rgba(42, 47, 104, 0.05);
  touch-action: pan-y;
  user-select: none;
  will-change: transform, opacity;
}

.question-card::before {
  position: absolute;
  content: "";
  pointer-events: none;
}

.question-card::before {
  top: -5px;
  right: 40px;
  width: 54px;
  height: 12px;
  border-radius: 3px;
  background: rgba(91, 75, 209, 0.17);
  transform: rotate(2deg);
}

.question-card:focus-visible,
button:focus-visible,
a:focus-visible {
  outline: 3px solid rgba(91, 75, 209, 0.29);
  outline-offset: 3px;
}

.card-topline {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.question-index {
  display: flex;
  gap: 5px;
  align-items: baseline;
  color: var(--ink-soft);
  font-size: 13px;
  font-weight: 650;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.03em;
}

#currentNumber {
  color: var(--ink);
  font-size: 20px;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.index-divider {
  color: rgba(48, 53, 94, 0.28);
}

.favorite-button {
  width: 44px;
  height: 44px;
  color: var(--ink-soft);
  background: transparent;
  transition: color 160ms ease, background 160ms ease, transform 160ms ease;
}

.favorite-button svg {
  width: 21px;
  height: 21px;
}

.favorite-button[aria-pressed="true"] {
  color: var(--accent);
  background: var(--accent-soft);
}

.favorite-button[aria-pressed="true"] svg,
.action-chip[aria-pressed="true"] svg {
  fill: currentColor;
}

.progress-track {
  position: absolute;
  top: 74px;
  right: 22px;
  left: 22px;
  width: auto;
  height: 3px;
  margin: 0;
  overflow: hidden;
  border-radius: 999px;
  background: rgba(48, 53, 102, 0.09);
}

.progress-track span {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: var(--accent);
  transition: width 420ms var(--ease);
}

.question-content {
  display: grid;
  flex: 1 1 auto;
  align-content: center;
  justify-items: center;
  padding: 36px 2px 22px;
  text-align: center;
}

.category-tag {
  display: inline-flex;
  min-height: 28px;
  padding: 0 10px;
  align-items: center;
  border-radius: 999px;
  color: var(--accent-strong);
  background: var(--accent-soft);
  font-size: 11px;
  font-weight: 750;
  letter-spacing: 0.05em;
}

#questionText {
  max-width: 13em;
  margin: 0;
  font-size: clamp(31px, 8.2vw, 42px);
  font-weight: 760;
  line-height: 1.36;
  letter-spacing: -0.035em;
  text-wrap: balance;
}

#questionText[data-length="short"] {
  max-width: 9em;
  font-size: clamp(36px, 9.2vw, 46px);
  line-height: 1.3;
}

#questionText[data-length="long"] {
  max-width: 15em;
  font-size: clamp(27px, 7vw, 35px);
  line-height: 1.42;
}

#questionText[data-length="extra-long"] {
  max-width: 17em;
  font-size: clamp(22px, 5.8vw, 29px);
  line-height: 1.48;
  letter-spacing: -0.025em;
}

.answer-section {
  display: grid;
  min-height: 104px;
  align-content: start;
  padding: 0 2px;
}

.answer-rule {
  display: flex;
  gap: 12px;
  align-items: center;
  color: var(--ink-soft);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.18em;
}

.answer-rule::after {
  height: 1px;
  flex: 1;
  background: var(--line);
  content: "";
}

.answer-placeholder,
.answer-text {
  margin: 16px 0 0;
}

.answer-placeholder {
  color: rgba(73, 78, 117, 0.46);
  font-size: 14px;
}

.answer-text {
  display: none;
  color: var(--accent-strong);
  font-size: clamp(19px, 5.3vw, 24px);
  font-weight: 750;
  line-height: 1.45;
  letter-spacing: -0.015em;
}

.answer-section.is-visible .answer-placeholder {
  display: none;
}

.answer-section.is-visible .answer-text {
  display: block;
  animation: answer-in 300ms var(--ease) both;
}

.reveal-button {
  display: inline-flex;
  min-height: 52px;
  padding: 0 20px;
  gap: 10px;
  align-self: center;
  align-items: center;
  justify-content: center;
  border: 0;
  border-radius: 999px;
  color: var(--card);
  background: var(--ink);
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 12px 24px -16px rgba(31, 35, 64, 0.58);
  transition: transform 160ms ease, background 160ms ease;
}

.eye-icon svg {
  width: 20px;
  height: 20px;
}

.swipe-hint {
  display: flex;
  gap: 10px;
  align-items: center;
  justify-content: center;
  margin-top: 16px;
  color: rgba(72, 77, 116, 0.44);
  font-size: 10px;
}

.swipe-hint i {
  width: 3px;
  height: 3px;
  border-radius: 50%;
  background: currentColor;
}

.mode-note {
  margin: 8px 0 -2px;
  color: var(--ink-soft);
  font-size: 11px;
  text-align: center;
}

.bottom-controls {
  display: grid;
  grid-template-columns: 1fr 1.35fr;
  gap: 11px;
  padding-top: 2px;
}

.nav-button {
  display: inline-flex;
  min-height: 54px;
  padding: 0 18px;
  gap: 9px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-control);
  font-size: 15px;
  font-weight: 750;
  cursor: pointer;
  transition: transform 160ms ease, background 160ms ease, border-color 160ms ease;
}

.nav-button.secondary {
  border: 1px solid var(--line);
  color: var(--ink);
  background: rgba(248, 248, 255, 0.58);
}

.nav-button.primary {
  border: 1px solid var(--accent);
  color: var(--card);
  background: var(--accent);
  box-shadow: 0 10px 26px -17px rgba(74, 62, 188, 0.72);
}

.nav-button[disabled] {
  opacity: 0.38;
  cursor: not-allowed;
}

.toast {
  position: fixed;
  z-index: 50;
  left: 50%;
  bottom: max(88px, calc(72px + env(safe-area-inset-bottom)));
  max-width: calc(100vw - 44px);
  padding: 11px 16px;
  border: 1px solid rgba(248, 248, 255, 0.13);
  border-radius: 999px;
  color: var(--card);
  background: rgba(31, 35, 64, 0.95);
  font-size: 13px;
  opacity: 0;
  pointer-events: none;
  transform: translate(-50%, 14px);
  transition: opacity 220ms ease, transform 220ms var(--ease);
}

.toast.is-visible {
  opacity: 1;
  transform: translate(-50%, 0);
}

.about-dialog {
  width: min(calc(100% - 32px), 430px);
  padding: 0;
  border: 0;
  border-radius: 26px;
  color: var(--ink);
  background: transparent;
}

.about-dialog::backdrop {
  background: rgba(31, 35, 64, 0.43);
  backdrop-filter: blur(5px);
}

.dialog-card {
  position: relative;
  padding: 28px 24px 24px;
  border: 1px solid var(--line);
  border-radius: 26px;
  background: var(--card);
  box-shadow: 0 28px 90px -34px rgba(31, 35, 86, 0.5);
}

.dialog-close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 42px;
  height: 42px;
}

.dialog-icon {
  display: grid;
  width: 44px;
  height: 44px;
  border-radius: 14px;
  color: var(--card);
  background: var(--accent);
  font-size: 21px;
  font-weight: 850;
  place-items: center;
}

.dialog-card h2 {
  margin: 20px 0 10px;
  font-size: 23px;
  letter-spacing: -0.03em;
}

.dialog-card p {
  margin: 10px 0;
  color: var(--ink-soft);
  font-size: 14px;
  line-height: 1.75;
}

.dialog-links {
  display: grid;
  gap: 8px;
  margin-top: 18px;
}

.dialog-links a {
  min-height: 42px;
  padding: 11px 13px;
  border-radius: 12px;
  color: var(--accent-strong);
  background: var(--accent-soft);
  font-size: 13px;
  font-weight: 650;
  text-decoration: none;
}

.question-card.exit-left {
  animation: exit-left 190ms ease-in both;
}

.question-card.exit-right {
  animation: exit-right 190ms ease-in both;
}

.question-card.enter-left {
  animation: enter-left 340ms var(--ease) both;
}

.question-card.enter-right {
  animation: enter-right 340ms var(--ease) both;
}

.question-card.is-snapping {
  transition: transform 280ms var(--ease), opacity 280ms ease;
}

@keyframes answer-in {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes exit-left {
  to { opacity: 0; transform: translate3d(-48px, 0, 0) rotate(-1.2deg); }
}

@keyframes exit-right {
  to { opacity: 0; transform: translate3d(48px, 0, 0) rotate(1.2deg); }
}

@keyframes enter-left {
  from { opacity: 0; transform: translate3d(-34px, 0, 0) rotate(-0.8deg); }
}

@keyframes enter-right {
  from { opacity: 0; transform: translate3d(34px, 0, 0) rotate(0.8deg); }
}

@media (hover: hover) {
  .action-chip:hover,
  .icon-button:hover,
  .favorite-button:hover,
  .dialog-close:hover {
    border-color: rgba(91, 75, 209, 0.25);
    color: var(--accent-strong);
    background: var(--accent-soft);
  }

  .nav-button:hover,
  .reveal-button:hover {
    transform: translateY(-2px);
  }

  .nav-button.primary:hover {
    background: var(--accent-strong);
  }

  .reveal-button:hover {
    background: #2c315a;
  }
}

@media (max-height: 730px) {
  .app-shell {
    padding-top: max(12px, env(safe-area-inset-top));
  }

  .brand small,
  .swipe-hint {
    display: none;
  }

  .quick-actions {
    padding: 10px 0 8px;
  }

  .question-card {
    min-height: 444px;
    padding-top: 18px;
  }

  .question-content {
    padding-top: 24px;
    padding-bottom: 14px;
  }

  .answer-section {
    min-height: 82px;
  }
}

@media (min-width: 540px) {
  body {
    padding: 24px 0;
  }

  .app-shell {
    min-height: calc(100dvh - 48px);
    border: 1px solid rgba(40, 45, 96, 0.09);
    border-radius: 34px;
    box-shadow: 0 40px 90px -52px rgba(31, 36, 88, 0.5);
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}