:root {
  --bg-main: #020608;
  --bg-card: #050b0f;
  --bg-card-soft: #050f13;
  --accent: #36ffb5;
  --accent-soft: rgba(54, 255, 181, 0.2);
  --accent-strong: #64ffd1;
  --text-main: #e5f7f0;
  --text-muted: #7aa59a;
  --border-subtle: rgba(54, 255, 181, 0.25);
  --shadow-soft: 0 0 20px rgba(0, 255, 170, 0.15);
  --radius-lg: 16px;
  --radius-pill: 999px;
  --transition-fast: 0.18s ease-out;
  --transition-med: 0.25s ease-out;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: radial-gradient(circle at top left, #021013 0, var(--bg-main) 45%, #000 100%);
  color: var(--text-main);
  display: flex;
  flex-direction: column;
}

.page {
  width: 100%;
  max-width: 1000px;
  margin: 1.5rem auto 4rem;
  padding: 0 1.5rem;
}

.site-header {
  width: 100%;
  max-width: 1000px;
  margin: 1.5rem auto 0.5rem;
  padding: 0 1.5rem 0.75rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid rgba(54, 255, 181, 0.25);
  backdrop-filter: blur(18px);
}

.title-block h1 {
  margin: 0;
  font-size: 1.9rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--accent-strong);
}

.title-block .subtitle {
  margin: 0.25rem 0 0.15rem;
  font-size: 0.9rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.title-block .creator {
  margin: 0;
  font-size: 0.82rem;
  color: var(--text-muted);
}

.title-block .creator span {
  color: var(--accent-strong);
}

.header-right {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.lang-nav a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2.2rem;
  padding: 0.2rem 0.7rem;
  margin-left: 0.1rem;
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--text-muted);
  background: rgba(7, 25, 22, 0.7);
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast), transform var(--transition-fast);
}

.lang-nav a:hover {
  border-color: var(--accent-soft);
  color: var(--accent-strong);
  box-shadow: 0 0 8px rgba(54, 255, 181, 0.35);
  transform: translateY(-1px);
}

.lang-nav a.active {
  background: linear-gradient(120deg, rgba(54, 255, 181, 0.18), rgba(0, 0, 0, 0.6));
  color: var(--accent-strong);
  border-color: var(--accent);
  box-shadow: 0 0 18px rgba(54, 255, 181, 0.5);
}

.theme-toggle {
  border-radius: 999px;
  border: 1px solid var(--border-subtle);
  background: radial-gradient(circle at 30% 30%, rgba(54, 255, 181, 0.2), rgba(0, 0, 0, 0.85));
  color: var(--accent-strong);
  width: 2.1rem;
  height: 2.1rem;
  font-size: 1rem;
  cursor: pointer;
  box-shadow: 0 0 16px rgba(54, 255, 181, 0.45);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), border-color var(--transition-fast);
}

.theme-toggle:hover {
  transform: translateY(-1px) scale(1.02);
  box-shadow: 0 0 20px rgba(54, 255, 181, 0.7);
  border-color: var(--accent);
}

.main-nav {
  width: 100%;
  max-width: 1000px;
  margin: 0 auto 0.5rem;
  padding: 0.4rem 1.5rem 0.6rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  border-bottom: 1px solid rgba(54, 255, 181, 0.15);
  background: linear-gradient(90deg, rgba(3, 16, 14, 0.85), rgba(1, 5, 7, 0.95));
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.65);
  position: sticky;
  top: 0;
  z-index: 20;
}

.main-nav a {
  font-size: 0.75rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--text-muted);
  padding: 0.25rem 0.7rem;
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast);
}

.main-nav a:hover {
  background: rgba(18, 63, 52, 0.9);
  color: var(--accent-strong);
  border-color: var(--accent-soft);
  transform: translateY(-1px);
}

.card {
  background: radial-gradient(circle at top left, rgba(6, 33, 29, 0.9), var(--bg-card-soft));
  border-radius: var(--radius-lg);
  margin: 1rem 0;
  box-shadow: var(--shadow-soft);
  border: 1px solid rgba(54, 255, 181, 0.25);
  overflow: hidden;
  position: relative;
}

.card::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  border: 1px solid transparent;
  background: linear-gradient(135deg, rgba(54, 255, 181, 0.25), transparent, rgba(54, 255, 181, 0.1));
  mix-blend-mode: soft-light;
  opacity: 0.14;
  pointer-events: none;
}

.card-header {
  width: 100%;
  padding: 0.9rem 1.1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  background: radial-gradient(circle at top left, rgba(22, 89, 73, 0.6), rgba(2, 10, 12, 0.98));
  border: none;
  color: var(--text-main);
  cursor: pointer;
  text-align: left;
  position: relative;
  z-index: 1;
}

.card-header h2 {
  margin: 0;
  font-size: 0.95rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.toggle-icon {
  font-size: 0.9rem;
  color: var(--accent-strong);
  transition: transform var(--transition-med);
}

.card.collapsible:not(.open) .toggle-icon {
  transform: rotate(-90deg);
}

.card-body {
  padding: 0.7rem 1.1rem 1.1rem;
  font-size: 0.9rem;
  color: var(--text-main);
  line-height: 1.6;
  display: none;
}

.card.open .card-body {
  display: block;
}

.card-body h3 {
  font-size: 0.9rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-strong);
  margin-top: 0.7rem;
  margin-bottom: 0.3rem;
}

.card-body p {
  margin: 0.35rem 0;
  color: var(--text-main);
}

.card-body ul {
  margin: 0.4rem 0 0.7rem;
  padding-left: 1.1rem;
}

.card-body li {
  margin-bottom: 0.2rem;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 0.25rem 2rem;
}

code {
  font-family: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  font-size: 0.82rem;
  padding: 0.05rem 0.3rem;
  border-radius: 0.4rem;
  background: rgba(3, 35, 26, 0.9);
  color: var(--accent-strong);
  border: 1px solid rgba(54, 255, 181, 0.35);
}

.site-footer {
  width: 100%;
  max-width: 1000px;
  margin: 0 auto 1.5rem;
  padding: 0.75rem 1.5rem 0.5rem;
  font-size: 0.78rem;
  color: var(--text-muted);
  border-top: 1px solid rgba(54, 255, 181, 0.25);
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
}

.site-footer .small {
  font-size: 0.75rem;
}

.back-to-top {
  position: fixed;
  right: 1.5rem;
  bottom: 1.5rem;
  width: 2.2rem;
  height: 2.2rem;
  border-radius: 999px;
  border: 1px solid rgba(54, 255, 181, 0.5);
  background: radial-gradient(circle at 30% 20%, rgba(54, 255, 181, 0.6), rgba(0, 0, 0, 0.95));
  color: var(--bg-main);
  font-size: 1rem;
  cursor: pointer;
  display: none;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 22px rgba(54, 255, 181, 0.7);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), opacity var(--transition-fast);
  z-index: 50;
}

.back-to-top.visible {
  display: flex;
  opacity: 1;
}

.back-to-top:hover {
  transform: translateY(-2px) scale(1.03);
  box-shadow: 0 0 26px rgba(54, 255, 181, 0.9);
}

@media (max-width: 700px) {
  .site-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }
  .header-right {
    align-self: stretch;
    justify-content: space-between;
  }
  .main-nav {
    padding-inline: 1rem;
  }
  .page {
    padding-inline: 1rem;
  }
}

/* ============================================
   TEMA CLARO — ACTIVADO POR: body.theme-light
   Estilo Ciber–Místico Verde (Modo Claro)
   ============================================ */

body.theme-light {
  --bg-main: #f7fffb;
  --bg-card: #ffffff;
  --bg-card-soft: #e8fff4;
  --accent: #009f66;
  --accent-soft: rgba(0, 159, 102, 0.25);
  --accent-strong: #00c47f;
  --text-main: #0f1a16;
  --text-muted: #4b6d62;
  --border-subtle: rgba(0, 159, 102, 0.25);
  --shadow-soft: 0 0 18px rgba(0, 120, 70, 0.15);
}

body.theme-light {
  background: radial-gradient(circle at top left, #ffffff 0, #e5fff2 50%, #d8f5e8 100%);
  color: var(--text-main);
}

/* Header y navegación */
body.theme-light .site-header {
  background: rgba(230, 255, 245, 0.9);
  border-color: var(--border-subtle);
  box-shadow: 0 0 12px rgba(0, 159, 102, 0.28);
}

body.theme-light .main-nav {
  background: rgba(240, 255, 250, 0.85);
  border-bottom: 1px solid var(--border-subtle);
}

body.theme-light .main-nav a {
  color: var(--text-muted);
}

body.theme-light .main-nav a:hover {
  color: var(--accent-strong);
  background: rgba(0, 159, 102, 0.18);
}

/* Botón de tema */
body.theme-light .theme-toggle {
  background: radial-gradient(circle at 40% 30%, rgba(0, 159, 102, 0.25), #ffffff);
  color: #00784c;
  border-color: rgba(0, 159, 102, 0.4);
  box-shadow: 0 0 16px rgba(0, 159, 102, 0.4);
}

/* Tarjetas (secciones) */
body.theme-light .card {
  background: radial-gradient(circle at top left, #ffffff, #ecfff6 80%);
  border-color: var(--border-subtle);
  box-shadow: 0 0 20px rgba(0, 159, 102, 0.15);
}

body.theme-light .card-header {
  background: linear-gradient(120deg, #d9fff0, #f2fff9);
  color: var(--text-main);
}

body.theme-light .card-body {
  color: var(--text-main);
}

body.theme-light code {
  background: #e4fff2;
  color: #00784c;
  border-color: rgba(0, 159, 102, 0.45);
}

/* Footer */
body.theme-light .site-footer {
  background: rgba(235, 255, 245, 0.7);
  border-top-color: var(--border-subtle);
}

/* Botón volver arriba */
body.theme-light .back-to-top {
  background: radial-gradient(circle at 20% 20%, #00c47f, #eafff5);
  color: #003722;
  border-color: rgba(0, 159, 102, 0.5);
}

/* Fuerza que el modo oscuro sea siempre el default */
body:not(.theme-light) {
  --bg-main: #020608;
  --bg-card: #050b0f;
  --bg-card-soft: #050f13;
  --accent: #36ffb5;
  --accent-soft: rgba(54, 255, 181, 0.2);
  --accent-strong: #64ffd1;
  --text-main: #e5f7f0;
  --text-muted: #7aa59a;
  --border-subtle: rgba(54, 255, 181, 0.25);
  --shadow-soft: 0 0 20px rgba(0, 255, 170, 0.15);
}