:root {
  --bg: #f5efe6;
  --panel: #fffdf9;
  --panel-alt: #f3e7d5;
  --ink: #1d1b1a;
  --muted: #655d57;
  --primary: #8d5a2b;
  --primary-dark: #6e431b;
  --accent: #d7b98a;
  --success: #3d7a4f;
  --shadow: 0 18px 50px rgba(56, 35, 18, 0.14);
  /* Superficies: se redefinen en oscuro para no dejar texto claro sobre fondo claro */
  --superficie-app: rgba(255, 255, 255, 0.38);
  --superficie-pastilla: rgba(255, 255, 255, 0.55);
  --btn-secundario-bg: #efe3d1;
  --btn-secundario-ink: var(--primary-dark);
  --cara-frente: linear-gradient(
    145deg,
    rgba(255, 255, 255, 0.9),
    rgba(250, 242, 232, 0.92)
  );
  --cara-dorso: linear-gradient(
    145deg,
    rgba(255, 250, 245, 1),
    rgba(240, 226, 205, 0.96)
  );
  --borde-suave: rgba(141, 90, 43, 0.2);
}

:root[data-theme="dark"] {
  --bg: #1c1a17;
  --panel: #262320;
  --panel-alt: #2c2925;
  --ink: #f2ede4;
  --muted: #b3ab9d;
  --primary: #e08c46;
  --primary-dark: #f0a868;
  --accent: #4a3c2c;
  --success: #6bbf82;
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.4);
  --superficie-app: rgba(255, 255, 255, 0.04);
  --superficie-pastilla: rgba(255, 255, 255, 0.07);
  --btn-secundario-bg: #3a352f;
  --btn-secundario-ink: #f0d9bd;
  --cara-frente: linear-gradient(145deg, #33302b, #2a2723);
  --cara-dorso: linear-gradient(145deg, #3a352e, #2f2b26);
  --borde-suave: rgba(224, 140, 70, 0.28);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  font-family: Arial, Helvetica, sans-serif;
  background: var(--bg);
  color: var(--ink);
  transition:
    background 0.2s ease,
    color 0.2s ease;
}

.sitenav {
  width: min(760px, 100%);
  margin: 0 auto 14px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 4px;
  font-size: 0.92rem;
}

.sitenav .nav-links {
  display: flex;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
}

.sitenav a,
.sitenav button {
  font-family: inherit;
  font-size: inherit;
  color: var(--muted);
  text-decoration: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px 0;
}

.sitenav a.active {
  color: var(--primary);
  border-bottom: 2px solid var(--primary);
  font-weight: 700;
}

.sitenav button#themeToggle {
  color: var(--primary);
  font-weight: 700;
}

body {
  min-height: 100vh;
  display: grid;
  place-items: start center; /* start en vertical: permite que la barra quede fija */
  padding: 24px;
}

.app {
  width: min(760px, 100%);
  background: var(--superficie-app);
  backdrop-filter: blur(6px);
  border: 1px solid var(--borde-suave);
  border-radius: 28px;
  box-shadow: var(--shadow);
  padding: 28px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 18px;
}

.eyebrow {
  margin: 0 0 8px;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--primary);
  font-size: 0.72rem;
  font-weight: 700;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 2.8rem);
  line-height: 1.08;
  color: var(--ink);
}

.btn {
  border: none;
  border-radius: 999px;
  padding: 12px 18px;
  font-size: 0.98rem;
  font-weight: 700;
  cursor: pointer;
  transition:
    transform 0.18s ease,
    box-shadow 0.18s ease,
    background 0.18s ease;
}

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

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

.btn.primary {
  background: var(--primary);
  color: white;
  box-shadow: 0 10px 20px rgba(141, 90, 43, 0.2);
}

.btn.secondary {
  background: var(--btn-secundario-bg);
  color: var(--btn-secundario-ink);
}

.btn.ghost {
  background: transparent;
  border: 1px solid rgba(141, 90, 43, 0.3);
  color: var(--primary-dark);
}

.lang-filters {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 4px;
}

.lang-pill {
  border: 1px solid var(--borde-suave);
  background: var(--superficie-pastilla);
  color: var(--muted);
  padding: 8px 14px;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 700;
  cursor: pointer;
  font-family: inherit;
}

.lang-pill.active {
  border-color: var(--primary);
  color: white;
  background: var(--primary);
}

.stats {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin: 18px 4px 20px;
  gap: 14px;
  color: var(--muted);
  font-weight: 700;
}

.counter {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--superficie-pastilla);
  padding: 10px 14px;
  border-radius: 999px;
  border: 1px solid var(--borde-suave);
}

.progress {
  font-size: 0.92rem;
  letter-spacing: 0.03em;
}

.card {
  height: 340px;
  perspective: 1200px;
  margin: 10px 0 20px;
  border-radius: 26px;
  cursor: pointer;
  user-select: none;
}

.card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transition: transform 0.7s ease;
  transform-style: preserve-3d;
}

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

.card-face {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 24px 22px 20px;
  border-radius: 26px;
  backface-visibility: hidden;
  background: var(--cara-frente);
  border: 1px solid var(--borde-suave);
  box-shadow: 0 12px 30px rgba(72, 44, 22, 0.12);
}

.card-back {
  transform: rotateY(180deg);
  background: var(--cara-dorso);
}

.tag {
  display: inline-flex;
  align-self: flex-start;
  padding: 7px 12px;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: rgba(141, 90, 43, 0.1);
  color: var(--primary-dark);
}

.tag.alt {
  background: rgba(61, 122, 79, 0.12);
  color: var(--success);
}

.card p {
  margin: 0;
  font-size: clamp(1.1rem, 2vw, 1.7rem);
  line-height: 1.5;
  text-wrap: balance;
}

.controls,
.meta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}

.meta {
  justify-content: space-between;
  margin-top: 18px;
  padding-top: 14px;
  border-top: 1px solid rgba(141, 90, 43, 0.14);
}

.learned {
  color: var(--success);
  font-weight: 700;
}

.deck-wrap {
  width: min(760px, 100%);
  margin: 0 0 40px;
}

.deck-title {
  font-size: 1rem;
  color: var(--primary-dark);
  margin: 26px 0 12px;
}

.deck-title a {
  color: inherit;
}

.mini-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 10px;
}

.mini-card {
  text-align: left;
  border: 1px solid rgba(141, 90, 43, 0.18);
  background: var(--panel);
  border-radius: 14px;
  padding: 12px 14px;
  cursor: pointer;
  font-family: inherit;
  font-size: 0.85rem;
  color: var(--ink);
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 8px;
  line-height: 1.4;
}

.mini-card:hover {
  border-color: var(--primary);
}

.mini-card.active {
  border-color: var(--primary);
  background: var(--panel-alt);
}

.mini-card .mini-check {
  color: var(--success);
  font-weight: 800;
  flex-shrink: 0;
}

@media (max-width: 640px) {
  .app {
    padding: 20px 16px;
  }
  .topbar {
    align-items: flex-start;
    flex-direction: column;
  }
  .controls {
    justify-content: stretch;
  }
  .controls .btn {
    flex: 1;
  }
  .meta {
    justify-content: center;
  }
  .card {
    height: 300px;
  }
}