:root {
  color-scheme: light;
  --ink: #162029;
  --muted: #60707f;
  --line: #dfe6ec;
  --paper: #fbfcfd;
  --surface: #ffffff;
  --accent: #176b87;
  --accent-strong: #0f4c5c;
  --soft-blue: #e9f6fb;
  --soft-green: #eef8f1;
  --soft-rose: #fff0f0;
  --shadow: 0 18px 45px rgba(22, 32, 41, 0.1);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "PingFang SC", "Microsoft YaHei", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    linear-gradient(135deg, rgba(233, 246, 251, 0.92), rgba(255, 240, 240, 0.56)),
    linear-gradient(45deg, rgba(238, 248, 241, 0.76), rgba(255, 255, 255, 0.85));
  color: var(--ink);
}

button {
  font: inherit;
}

.app-shell {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
  padding: 28px 0 40px;
}

.topbar {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 18px;
  padding: 6px 0 18px;
}

.eyebrow {
  margin: 0 0 6px;
  color: var(--accent-strong);
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: 3.45rem;
  line-height: 1;
}

.toolbar {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: end;
}

.counter,
.study-strip > div {
  min-width: 84px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.72);
}

.counter span,
.study-strip strong {
  display: block;
  color: var(--accent-strong);
  font-size: 1.35rem;
  font-weight: 850;
  line-height: 1;
}

.counter small,
.study-strip span {
  display: block;
  margin-top: 5px;
  color: var(--muted);
  font-size: 0.78rem;
}

.icon-button,
.mini-button,
.word-button {
  border: 0;
  cursor: pointer;
}

.icon-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 0 16px;
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
  box-shadow: 0 12px 24px rgba(23, 107, 135, 0.22);
  font-weight: 800;
}

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

.icon-button:disabled {
  cursor: wait;
  opacity: 0.72;
}

.icon-button:active,
.mini-button:active,
.word-button:active {
  transform: translateY(1px);
}

.study-strip {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-bottom: 18px;
}

.cards-grid {
  display: grid;
  grid-template-columns: minmax(0, 560px);
  justify-content: center;
  gap: 14px;
}

.word-card {
  display: grid;
  grid-template-rows: auto auto auto 1fr auto;
  gap: 11px;
  min-height: 620px;
  padding: 12px;
  border: 1px solid rgba(22, 32, 41, 0.08);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.9);
  box-shadow: var(--shadow);
}

.word-card.is-known {
  outline: 2px solid rgba(35, 146, 92, 0.32);
}

.memory-image {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 11;
  overflow: hidden;
  border: 1px solid rgba(22, 32, 41, 0.08);
  border-radius: 8px;
  background:
    linear-gradient(135deg, rgba(233, 246, 251, 0.92), rgba(255, 240, 240, 0.7)),
    #edf3f7;
}

.ai-memory-img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0;
  transform: scale(1.02);
  transition: opacity 280ms ease, transform 360ms ease;
}

.memory-image[data-state="ready"] .ai-memory-img {
  opacity: 1;
  transform: scale(1);
}

.image-placeholder {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  justify-items: center;
  gap: 8px;
  padding: 20px;
  text-align: center;
  color: #344554;
  background:
    radial-gradient(circle at 50% 36%, rgba(255, 255, 255, 0.92), rgba(255, 255, 255, 0.2) 42%),
    linear-gradient(135deg, rgba(233, 246, 251, 0.72), rgba(255, 231, 168, 0.46));
  transition: opacity 220ms ease;
}

.memory-image[data-state="ready"] .image-placeholder {
  opacity: 0;
  pointer-events: none;
}

.image-placeholder strong {
  font-size: 1.02rem;
}

.image-placeholder small {
  max-width: 320px;
  color: var(--muted);
  line-height: 1.5;
}

.image-spinner {
  width: 34px;
  height: 34px;
  border: 3px solid rgba(23, 107, 135, 0.18);
  border-top-color: var(--accent);
  border-radius: 999px;
  animation: spin 900ms linear infinite;
}

.memory-image[data-state="error"] .image-spinner {
  display: none;
}

.memory-image[data-state="error"] .image-placeholder {
  background: linear-gradient(135deg, rgba(255, 240, 240, 0.92), rgba(255, 255, 255, 0.78));
}

.image-overlay {
  position: absolute;
  left: 18px;
  right: 18px;
  bottom: 18px;
  display: grid;
  gap: 5px;
  max-width: calc(100% - 36px);
  padding: 14px 16px;
  border: 1px solid rgba(255, 255, 255, 0.52);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.84);
  box-shadow: 0 18px 40px rgba(22, 32, 41, 0.18);
  backdrop-filter: blur(12px);
}

.image-word {
  overflow-wrap: anywhere;
  color: var(--ink);
  font-size: clamp(2.1rem, 8vw, 4.35rem);
  font-weight: 900;
  line-height: 0.92;
}

.image-meaning {
  color: #41515f;
  font-weight: 760;
  line-height: 1.3;
}

.word-line {
  display: block;
}

.word-button {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  min-width: 0;
  max-width: 100%;
  min-height: 38px;
  padding: 0;
  background: transparent;
  color: var(--ink);
  text-align: left;
  font-size: var(--word-size, 1.5rem);
  font-weight: 850;
  line-height: 1;
}

.word-text {
  min-width: 0;
  white-space: nowrap;
}

.word-button span:not(.word-text) {
  display: inline-grid;
  place-items: center;
  width: 26px;
  height: 26px;
  flex: 0 0 auto;
  border-radius: 999px;
  background: var(--soft-blue);
  color: var(--accent-strong);
  font-size: 0.8rem;
}

.word-button:hover {
  color: var(--accent-strong);
}

.pos {
  display: inline-block;
  margin-top: 4px;
  color: #8a4f26;
  font-weight: 800;
  font-size: 0.88rem;
}

.phonetic {
  margin: -5px 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.meaning {
  margin: 0;
  color: var(--ink);
  font-weight: 760;
  line-height: 1.45;
}

.tip {
  margin: 0;
  padding: 10px 12px;
  border: 1px solid rgba(23, 107, 135, 0.14);
  border-radius: 8px;
  background: rgba(233, 246, 251, 0.72);
  color: #274554;
  font-size: 0.92rem;
  font-weight: 650;
  line-height: 1.5;
}

.tip span {
  display: inline-block;
  margin-right: 8px;
  color: var(--accent-strong);
  font-size: 0.78rem;
  font-weight: 850;
}

.memory {
  margin: 0;
  color: #41515f;
  font-size: 0.92rem;
  line-height: 1.55;
}

.example {
  min-height: 72px;
  margin: 0;
  padding: 10px;
  border-left: 4px solid var(--accent);
  border-radius: 4px;
  background: #f6fafb;
  color: #344554;
  font-size: 0.9rem;
  line-height: 1.5;
}

.actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.mini-button {
  min-height: 34px;
  padding: 0 10px;
  border-radius: 8px;
  background: #edf3f7;
  color: #243441;
  font-weight: 750;
}

.mini-button.primary {
  min-height: 42px;
  padding: 0 18px;
  background: var(--accent);
  color: #fff;
  box-shadow: 0 10px 22px rgba(23, 107, 135, 0.18);
}

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

.mini-button[data-known="true"] {
  background: #e5f7ee;
  color: #17613c;
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 22px;
  max-width: min(520px, calc(100% - 32px));
  padding: 11px 14px;
  border-radius: 8px;
  background: rgba(22, 32, 41, 0.92);
  color: #fff;
  opacity: 0;
  transform: translate(-50%, 14px);
  pointer-events: none;
  transition: opacity 160ms ease, transform 160ms ease;
  font-size: 0.92rem;
}

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

.notice {
  grid-column: 1 / -1;
  min-height: 240px;
  padding: 24px;
  border: 1px solid rgba(22, 32, 41, 0.08);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.72);
}

.notice strong {
  display: block;
  margin-bottom: 10px;
  font-size: 1.2rem;
}

.notice p {
  max-width: 720px;
  margin: 0;
  color: #41515f;
  line-height: 1.7;
}

@media (max-width: 720px) {
  .app-shell {
    width: min(100% - 22px, 620px);
    padding-top: 18px;
  }

  .topbar {
    align-items: stretch;
    flex-direction: column;
  }

  h1 {
    font-size: 2.35rem;
  }

  .toolbar {
    justify-content: space-between;
  }

  .study-strip {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .cards-grid {
    grid-template-columns: 1fr;
  }

  .word-card {
    min-height: auto;
  }

  .memory-image {
    aspect-ratio: 16 / 12;
  }
}

@media (min-width: 1024px) {
  .app-shell {
    width: min(1240px, calc(100% - 64px));
    padding-top: 24px;
  }

  .topbar {
    padding-bottom: 16px;
  }

  h1 {
    font-size: 3.65rem;
  }

  .study-strip {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    margin-bottom: 18px;
  }

  .cards-grid {
    grid-template-columns: minmax(0, 1120px);
  }

  .word-card {
    grid-template-columns: minmax(0, 1.28fr) minmax(320px, 0.72fr);
    grid-template-rows: auto auto auto auto 1fr auto auto;
    align-items: start;
    gap: 12px 22px;
    min-height: 560px;
    padding: 16px;
  }

  .memory-image {
    grid-column: 1;
    grid-row: 1 / 8;
    height: 100%;
    min-height: 528px;
    aspect-ratio: auto;
  }

  .word-line,
  .phonetic,
  .meaning,
  .tip,
  .memory,
  .example,
  .actions {
    grid-column: 2;
  }

  .word-line {
    padding-top: 8px;
  }

  .word-button {
    min-height: 46px;
  }

  .phonetic {
    font-size: 1rem;
  }

  .meaning {
    font-size: 1.1rem;
  }

  .memory {
    font-size: 0.98rem;
  }

  .example {
    min-height: 82px;
    font-size: 0.96rem;
  }

  .actions {
    align-self: end;
  }

  .mini-button.primary {
    width: 100%;
    min-height: 48px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition: none !important;
  }
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}