/* Propuesta Almondale_2: estructura comun para clases navegables */
:root {
  --azul: #2563eb;
  --azul-oscuro: #1e3a8a;
  --violeta: #7c3aed;
  --verde: #16a34a;
  --naranjo: #f97316;
  --rojo: #dc2626;
  --gris-900: #0f172a;
  --gris-700: #334155;
  --gris-500: #64748b;
  --gris-200: #e2e8f0;
  --gris-100: #f1f5f9;
  --blanco: #ffffff;
  --sombra: 0 20px 50px rgba(15, 23, 42, 0.12);
  --radio: 22px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Segoe UI", Arial, sans-serif;
  color: var(--gris-900);
  background:
    radial-gradient(circle at top left, rgba(37, 99, 235, 0.14), transparent 32rem),
    radial-gradient(circle at bottom right, rgba(124, 58, 237, 0.13), transparent 30rem),
    #f8fafc;
  line-height: 1.65;
}

a {
  color: inherit;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid rgba(226, 232, 240, 0.9);
  backdrop-filter: blur(14px);
}

.topbar-inner {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0.9rem 1.2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  text-decoration: none;
  font-weight: 800;
}

.brand-mark {
  width: 42px;
  height: 42px;
  border-radius: 14px;
  display: grid;
  place-items: center;
  color: white;
  background: linear-gradient(135deg, var(--azul), var(--violeta));
  box-shadow: 0 10px 25px rgba(37, 99, 235, 0.28);
}

.brand small {
  display: block;
  color: var(--gris-500);
  font-weight: 600;
}

.nav-main,
.nav-actions,
.footer-nav {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  flex-wrap: wrap;
}

.nav-main a,
.nav-actions a,
.footer-nav a,
.btn {
  border: 1px solid var(--gris-200);
  background: var(--blanco);
  color: var(--gris-700);
  border-radius: 999px;
  padding: 0.62rem 0.95rem;
  text-decoration: none;
  font-weight: 700;
  font-size: 0.92rem;
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}

.nav-main a:hover,
.nav-actions a:hover,
.footer-nav a:hover,
.btn:hover {
  transform: translateY(-2px);
  border-color: rgba(37, 99, 235, 0.45);
  box-shadow: 0 10px 22px rgba(15, 23, 42, 0.09);
}

.btn-primary {
  color: white;
  border-color: transparent;
  background: linear-gradient(135deg, var(--azul), var(--violeta));
}

.hero {
  max-width: 1180px;
  margin: 0 auto;
  padding: 4.5rem 1.2rem 2.5rem;
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(280px, 0.75fr);
  gap: 2rem;
  align-items: center;
}

.hero-card,
.panel,
.lesson-card,
.course-card,
.toc-card {
  background: rgba(255, 255, 255, 0.94);
  border: 1px solid rgba(226, 232, 240, 0.92);
  border-radius: var(--radio);
  box-shadow: var(--sombra);
}

.hero-card {
  padding: 2.5rem;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  color: var(--azul);
  background: #dbeafe;
  border-radius: 999px;
  padding: 0.35rem 0.75rem;
  font-weight: 800;
  font-size: 0.88rem;
}

h1,
h2,
h3 {
  line-height: 1.15;
}

h1 {
  margin: 1rem 0;
  font-size: clamp(2.1rem, 5vw, 4.4rem);
  letter-spacing: -0.055em;
}

h2 {
  margin: 0 0 1rem;
  font-size: clamp(1.65rem, 3vw, 2.45rem);
}

h3 {
  margin: 0 0 0.75rem;
  font-size: 1.25rem;
}

.lead {
  font-size: 1.18rem;
  color: var(--gris-700);
  max-width: 68ch;
}

.hero-aside {
  padding: 1.4rem;
}

.metric {
  padding: 1rem;
  border-radius: 18px;
  background: linear-gradient(135deg, #eff6ff, #f5f3ff);
  margin-bottom: 0.8rem;
}

.metric strong {
  display: block;
  color: var(--azul-oscuro);
  font-size: 1.55rem;
}

.wrap {
  max-width: 1180px;
  margin: 0 auto;
  padding: 1.4rem 1.2rem 4rem;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.course-card {
  padding: 1.35rem;
  text-decoration: none;
  min-height: 210px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}

.course-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 24px 55px rgba(15, 23, 42, 0.16);
}

.course-card .number {
  width: 54px;
  height: 54px;
  border-radius: 18px;
  display: grid;
  place-items: center;
  color: white;
  background: linear-gradient(135deg, var(--azul), var(--violeta));
  font-size: 1.35rem;
  font-weight: 900;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin-top: 0.9rem;
}

.tag {
  color: var(--gris-700);
  background: var(--gris-100);
  border-radius: 999px;
  padding: 0.3rem 0.65rem;
  font-size: 0.84rem;
  font-weight: 700;
}

.lesson-layout {
  max-width: 1180px;
  margin: 0 auto;
  padding: 1.4rem 1.2rem 5.5rem;
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  gap: 1.2rem;
  align-items: start;
}

.toc-card {
  position: sticky;
  top: 88px;
  padding: 1rem;
}

.toc-card nav {
  display: grid;
  gap: 0.45rem;
}

.toc-card a {
  text-decoration: none;
  color: var(--gris-700);
  border-radius: 14px;
  padding: 0.7rem 0.8rem;
  font-weight: 750;
}

.toc-card a:hover,
.toc-card a.activo {
  color: var(--azul-oscuro);
  background: #dbeafe;
}

.progress-wrap {
  margin-top: 1rem;
  height: 10px;
  border-radius: 999px;
  background: var(--gris-200);
  overflow: hidden;
}

.progress-bar {
  width: 0%;
  height: 100%;
  background: linear-gradient(90deg, var(--azul), var(--violeta));
}

.lesson-card {
  padding: clamp(1.3rem, 4vw, 2.6rem);
  overflow: hidden;
}

.lesson-hero {
  display: grid;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.lesson-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
}

.pill {
  display: inline-flex;
  border-radius: 999px;
  background: var(--gris-100);
  color: var(--gris-700);
  padding: 0.4rem 0.75rem;
  font-weight: 800;
  font-size: 0.86rem;
}

.objective {
  border-radius: 24px;
  padding: 1.35rem;
  background: linear-gradient(135deg, #dbeafe, #ede9fe);
  border: 1px solid rgba(37, 99, 235, 0.16);
}

.objective h2 {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  color: var(--azul-oscuro);
  margin-bottom: 0.55rem;
}

.class-section {
  padding: 1.35rem 0;
  border-top: 1px solid var(--gris-200);
  scroll-margin-top: 100px;
}

.class-section:first-of-type {
  border-top: 0;
}

.section-label {
  display: inline-block;
  color: var(--azul);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: 900;
  font-size: 0.78rem;
  margin-bottom: 0.55rem;
}

.callout {
  border-left: 5px solid var(--azul);
  background: #eff6ff;
  border-radius: 18px;
  padding: 1rem 1.1rem;
  margin: 1rem 0;
}

.callout.success {
  border-left-color: var(--verde);
  background: #ecfdf5;
}

.callout.warning {
  border-left-color: var(--naranjo);
  background: #fff7ed;
}

.concept-grid,
.exercise-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.9rem;
  margin: 1rem 0;
}

.concept,
.exercise {
  border: 1px solid var(--gris-200);
  background: white;
  border-radius: 18px;
  padding: 1rem;
}

.concept strong {
  color: var(--azul-oscuro);
}

.media-box {
  margin: 1.2rem 0;
  border: 1px solid var(--gris-200);
  border-radius: 22px;
  padding: 1rem;
  background: white;
}

.media-box img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 0 auto;
  border-radius: 16px;
}

.media-box figcaption {
  margin-top: 0.75rem;
  color: var(--gris-500);
  text-align: center;
  font-weight: 650;
}

.steps {
  counter-reset: paso;
  display: grid;
  gap: 0.8rem;
  padding: 0;
  margin: 1rem 0;
  list-style: none;
}

.steps li {
  counter-increment: paso;
  position: relative;
  padding: 1rem 1rem 1rem 3.5rem;
  border-radius: 18px;
  background: var(--gris-100);
}

.steps li::before {
  content: counter(paso);
  position: absolute;
  left: 1rem;
  top: 1rem;
  width: 1.7rem;
  height: 1.7rem;
  border-radius: 50%;
  display: grid;
  place-items: center;
  color: white;
  background: var(--azul);
  font-weight: 900;
}

.bottom-nav {
  position: sticky;
  bottom: 0;
  z-index: 45;
  background: rgba(255, 255, 255, 0.94);
  border-top: 1px solid var(--gris-200);
  backdrop-filter: blur(14px);
}

.bottom-nav-inner {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0.8rem 1.2rem;
  display: flex;
  justify-content: space-between;
  gap: 0.8rem;
}

.site-footer {
  border-top: 1px solid var(--gris-200);
  background: white;
  color: var(--gris-500);
  padding: 2rem 1.2rem;
  text-align: center;
}

@media (max-width: 920px) {
  .hero,
  .lesson-layout {
    grid-template-columns: 1fr;
  }

  .toc-card {
    position: static;
  }

  .grid,
  .concept-grid,
  .exercise-grid {
    grid-template-columns: 1fr;
  }

  .topbar-inner,
  .bottom-nav-inner {
    align-items: flex-start;
    flex-direction: column;
  }
}

@media (max-width: 640px) {
  .hero {
    padding-top: 2rem;
  }

  .hero-card,
  .lesson-card {
    padding: 1.2rem;
  }

  .nav-main,
  .nav-actions,
  .footer-nav {
    width: 100%;
  }

  .nav-main a,
  .nav-actions a,
  .footer-nav a,
  .btn {
    flex: 1 1 auto;
    text-align: center;
  }
}