:root {
  --bg: #f4f1e8;
  --panel: #ffffff;
  --ink: #1f2d20;
  --muted: #5c6b5d;
  --accent: #2f6b3c;
  --accent-dark: #1f4a29;
  --amber: #b5762b;
  --danger: #a4442f;
  --line: #d9d3bf;
  --radius: 14px;
  --shadow: 0 6px 20px rgba(31, 45, 32, 0.12);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14201a;
    --panel: #1b2a22;
    --ink: #eae7da;
    --muted: #9db09e;
    --accent: #6fbf7c;
    --accent-dark: #8fd39a;
    --amber: #d9a35c;
    --danger: #e08a75;
    --line: #2d3d33;
    --shadow: 0 6px 24px rgba(0, 0, 0, 0.4);
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 18px clamp(18px, 5vw, 72px);
  border-bottom: 1px solid var(--line);
  background: rgba(244, 241, 232, 0.94);
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(10px);
}

@media (prefers-color-scheme: dark) {
  .site-header {
    background: rgba(20, 32, 26, 0.94);
  }
}

.brand {
  color: var(--accent-dark);
  font-size: 1rem;
  font-weight: 800;
  text-decoration: none;
}

.site-header nav {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
  font-size: 0.9rem;
}

.site-header nav a {
  color: var(--muted);
  text-decoration: none;
}

.site-header nav a:hover,
.site-header nav a[aria-current="page"] {
  color: var(--accent-dark);
}

.topbar {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: space-between;
  align-items: center;
  max-width: 900px;
  margin: 0 auto;
  padding: 1.25rem 1.5rem 0.75rem;
}

.title-block h1 {
  margin: 0 0 0.2rem;
  color: var(--accent-dark);
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(1.45rem, 4vw, 2.25rem);
  font-weight: 500;
  line-height: 1.05;
}

.subtitle {
  max-width: 58ch;
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.45;
}

.progress-block {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 0.25rem;
  min-width: 160px;
}

.progress-bar {
  width: 160px;
  height: 8px;
  border-radius: 999px;
  background: var(--line);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: var(--accent);
  transition: width 0.25s ease;
}

#progress-label {
  color: var(--muted);
  font-size: 0.75rem;
}

.category-bar {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
  justify-content: center;
  max-width: 900px;
  margin: 0 auto;
  padding: 0.5rem 1rem 1rem;
}

.chip {
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--panel);
  color: var(--ink);
  cursor: pointer;
  font-size: 0.78rem;
  padding: 0.35rem 0.8rem;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

.chip:hover {
  border-color: var(--accent);
}

.chip.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
}

.stage {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  max-width: 640px;
  margin: 0 auto;
  padding: 0 1rem 3rem;
}

.deck-info {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  color: var(--muted);
  font-size: 0.8rem;
}

.uncertain-toggle {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  cursor: pointer;
}

.card {
  width: 100%;
  max-width: 420px;
  aspect-ratio: 3 / 4;
  perspective: 1400px;
  cursor: pointer;
  outline: none;
}

.card:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 6px;
}

.card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transition: transform 0.5s cubic-bezier(.4,.2,.2,1);
  transform-style: preserve-3d;
}

.card.flipped .card-inner {
  transform: rotateY(180deg);
}

.card-face {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  overflow: hidden;
  padding: 1.25rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow);
  backface-visibility: hidden;
  text-align: center;
}

.card-back {
  justify-content: center;
  gap: 0.6rem;
  transform: rotateY(180deg);
}

.image-wrap {
  position: relative;
  display: flex;
  flex: 1;
  align-items: center;
  justify-content: center;
  width: 100%;
  margin-bottom: 0.75rem;
  overflow: hidden;
  border-radius: 10px;
  background: linear-gradient(160deg, var(--line), transparent);
}

.image-wrap img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.image-placeholder {
  color: var(--muted);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.1rem;
  opacity: 0.7;
}

.image-loading {
  position: absolute;
  bottom: 0.5rem;
  border-radius: 999px;
  background: var(--panel);
  color: var(--muted);
  font-size: 0.7rem;
  padding: 0.15rem 0.5rem;
}

.common-name {
  color: var(--ink);
  font-size: 1.15rem;
  font-weight: 650;
}

.uncertain-badge {
  margin-top: 0.35rem;
  border: 1px solid var(--amber);
  border-radius: 999px;
  color: var(--amber);
  font-size: 0.7rem;
  padding: 0.1rem 0.6rem;
}

.flip-hint {
  margin-top: auto;
  padding-top: 0.5rem;
  color: var(--muted);
  font-size: 0.7rem;
}

.sci-name {
  color: var(--accent-dark);
  font-size: 1.3rem;
  font-style: italic;
}

.category-tag {
  color: var(--muted);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.note {
  max-width: 30ch;
  color: var(--ink);
  font-size: 0.9rem;
}

.wiki-link {
  margin-top: 0.5rem;
  color: var(--accent);
  font-size: 0.8rem;
  text-decoration: none;
}

.wiki-link:hover {
  text-decoration: underline;
}

.controls,
.review-controls {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.6rem;
}

.btn {
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--panel);
  color: var(--ink);
  cursor: pointer;
  font-size: 0.85rem;
  padding: 0.55rem 1.1rem;
  transition: transform 0.1s ease, background 0.15s ease;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn:active {
  transform: translateY(0);
}

.btn-primary {
  border-color: var(--accent);
  background: var(--accent);
  color: #ffffff;
  font-weight: 650;
}

.btn-known {
  border-color: var(--accent);
  color: var(--accent-dark);
}

.btn-learning {
  border-color: var(--danger);
  color: var(--danger);
}

.btn-ghost {
  color: var(--muted);
}

.stats {
  color: var(--muted);
  font-size: 0.8rem;
  text-align: center;
}

.site-footer {
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.85rem;
  padding: 1rem clamp(18px, 5vw, 72px);
  text-align: center;
}

.site-footer p {
  margin: 0;
}

@media (max-width: 620px) {
  .site-header {
    display: block;
  }

  .site-header nav {
    margin-top: 12px;
  }
}

@media (max-width: 480px) {
  .topbar {
    align-items: flex-start;
    flex-direction: column;
  }

  .progress-block {
    align-items: flex-start;
    width: 100%;
  }

  .progress-bar {
    width: 100%;
  }

  .deck-info {
    align-items: flex-start;
    flex-direction: column;
    gap: 0.5rem;
  }
}