/* ================================================================
   MatemáticaEM · styles.css
   Plataforma educativa de Matemática · Enseñanza Media Chile
   ================================================================ */

/* ----------------------------------------------------------------
   1. VARIABLES Y RESET
---------------------------------------------------------------- */
:root {
  --bg-dark:       #0b0f1a;
  --bg-card:       #111827;
  --bg-card-hover: #1a2236;
  --bg-section:    #0d1220;
  --border:        rgba(255,255,255,.07);
  --border-glow:   rgba(56,189,248,.18);

  --primary:    #0ea5e9;   /* azul eléctrico */
  --primary-d:  #0369a1;   /* azul oscuro */
  --accent:     #f97316;   /* naranja */
  --accent-2:   #22d3ee;   /* cian */
  --text:       #e2e8f0;
  --text-muted: #64748b;
  --text-light: #94a3b8;
  --white:      #ffffff;

  --radius-sm:  8px;
  --radius:     14px;
  --radius-lg:  22px;
  --radius-xl:  32px;

  --shadow-card: 0 4px 24px rgba(0,0,0,.4);
  --shadow-glow: 0 0 40px rgba(14,165,233,.12);
  --shadow-hover: 0 12px 40px rgba(14,165,233,.2);

  --font-display: 'Syne', sans-serif;
  --font-body:    'DM Sans', sans-serif;
  --font-mono:    'JetBrains Mono', monospace;

  --nav-h: 68px;
  --transition: .3s cubic-bezier(.4,0,.2,1);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-h);
}

body {
  background-color: var(--bg-dark);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
button { cursor: pointer; font-family: inherit; border: none; background: none; }
input, textarea { font-family: inherit; }

/* ----------------------------------------------------------------
   2. TIPOGRAFÍA GLOBAL
---------------------------------------------------------------- */
h1, h2, h3, h4 { font-family: var(--font-display); line-height: 1.15; }
h1 { font-size: clamp(2.4rem, 6vw, 4.2rem); font-weight: 800; }
h2 { font-size: clamp(1.8rem, 4vw, 2.8rem); font-weight: 700; }
h3 { font-size: 1.15rem; font-weight: 600; }
h4 { font-size: 0.9rem; font-weight: 600; text-transform: uppercase; letter-spacing: .1em; color: var(--text-muted); }

/* ----------------------------------------------------------------
   3. LAYOUT HELPERS
---------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 100px 0;
  position: relative;
}

.section-header {
  text-align: center;
  margin-bottom: 60px;
}

.section-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: .72rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: .14em;
  color: var(--primary);
  background: rgba(14,165,233,.1);
  border: 1px solid rgba(14,165,233,.25);
  border-radius: 100px;
  padding: 5px 14px;
  margin-bottom: 18px;
}

.section-title {
  color: var(--white);
  margin-bottom: 14px;
}

.section-desc {
  color: var(--text-light);
  max-width: 540px;
  margin: 0 auto;
  font-size: 1.05rem;
}

/* ----------------------------------------------------------------
   4. NAVBAR
---------------------------------------------------------------- */
.navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-h);
  z-index: 1000;
  transition: background var(--transition), box-shadow var(--transition);
  backdrop-filter: blur(0);
}

.navbar.scrolled {
  background: rgba(11,15,26,.92);
  backdrop-filter: blur(18px);
  box-shadow: 0 1px 0 var(--border);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

/* Logo */
.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
  transition: opacity var(--transition);
}
.nav-logo:hover { opacity: .8; }

.logo-icon {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--primary);
  line-height: 1;
  font-family: var(--font-display);
}

.logo-text {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
  white-space: nowrap;
}
.logo-text strong { color: var(--primary); }

/* Nav links */
.nav-links {
  display: flex;
  align-items: center;
  gap: 6px;
}

.nav-link {
  font-size: .9rem;
  font-weight: 500;
  color: var(--text-light);
  padding: 7px 14px;
  border-radius: var(--radius-sm);
  transition: color var(--transition), background var(--transition);
  white-space: nowrap;
}

.nav-link:hover,
.nav-link.active {
  color: var(--white);
  background: rgba(255,255,255,.07);
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  padding: 8px;
  transition: background var(--transition);
}
.hamburger span {
  display: block;
  height: 2px;
  background: var(--text-light);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}
.hamburger:hover { background: rgba(255,255,255,.06); }
.hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Overlay */
.nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.6);
  z-index: 999;
  backdrop-filter: blur(2px);
}
.nav-overlay.active { display: block; }

/* ----------------------------------------------------------------
   5. HERO
---------------------------------------------------------------- */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  position: relative;
  overflow: hidden;
  padding: calc(var(--nav-h) + 60px) 24px 80px;
}

/* Background elements */
.hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 0;
}

.grid-lines {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(14,165,233,.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(14,165,233,.04) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse 80% 80% at 50% 50%, black 40%, transparent 100%);
}

.hero-glow {
  position: absolute;
  border-radius: 50%;
  filter: blur(100px);
}
.glow1 {
  width: 600px; height: 600px;
  top: -150px; right: -100px;
  background: radial-gradient(circle, rgba(14,165,233,.15) 0%, transparent 70%);
}
.glow2 {
  width: 400px; height: 400px;
  bottom: 0; left: -50px;
  background: radial-gradient(circle, rgba(249,115,22,.1) 0%, transparent 70%);
}

/* Floating math symbols */
.floating-symbols {
  position: absolute;
  inset: 0;
}
.sym {
  position: absolute;
  font-family: var(--font-display);
  font-weight: 800;
  color: rgba(14,165,233,.08);
  user-select: none;
  animation: floatSym linear infinite;
}
.sym1  { font-size:5rem; top:8%;  left:5%;   animation-duration:18s; animation-delay:0s; }
.sym2  { font-size:7rem; top:15%; right:8%;  animation-duration:22s; animation-delay:-3s; }
.sym3  { font-size:4rem; top:60%; left:3%;   animation-duration:16s; animation-delay:-6s; }
.sym4  { font-size:6rem; top:70%; right:6%;  animation-duration:20s; animation-delay:-9s; }
.sym5  { font-size:8rem; top:30%; left:50%;  animation-duration:25s; animation-delay:-4s; }
.sym6  { font-size:5rem; top:45%; right:18%; animation-duration:19s; animation-delay:-7s; }
.sym7  { font-size:6rem; top:80%; left:30%;  animation-duration:21s; animation-delay:-2s; }
.sym8  { font-size:4rem; top:20%; left:28%;  animation-duration:17s; animation-delay:-11s; }
.sym9  { font-size:5rem; top:55%; left:70%;  animation-duration:23s; animation-delay:-5s; }
.sym10 { font-size:3rem; top:90%; right:25%; animation-duration:15s; animation-delay:-8s; }

@keyframes floatSym {
  0%, 100% { transform: translateY(0) rotate(0deg); }
  33%       { transform: translateY(-20px) rotate(5deg); }
  66%       { transform: translateY(10px) rotate(-3deg); }
}

/* Hero content */
.hero-content {
  position: relative;
  z-index: 1;
  max-width: 960px;
  margin: 0 auto;
  text-align: center;
}

/* Animate-in state */
[data-animate] {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity .7s ease, transform .7s ease;
}
[data-animate].visible {
  opacity: 1;
  transform: translateY(0);
}
[data-delay="50"]  { transition-delay: .05s; }
[data-delay="80"]  { transition-delay: .08s; }
[data-delay="100"] { transition-delay: .1s;  }
[data-delay="160"] { transition-delay: .16s; }
[data-delay="200"] { transition-delay: .2s;  }
[data-delay="240"] { transition-delay: .24s; }
[data-delay="250"] { transition-delay: .25s; }
[data-delay="320"] { transition-delay: .32s; }
[data-delay="400"] { transition-delay: .4s;  }

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: .8rem;
  font-weight: 500;
  color: var(--text-light);
  background: rgba(255,255,255,.05);
  border: 1px solid var(--border);
  border-radius: 100px;
  padding: 7px 16px;
  margin-bottom: 28px;
  font-family: var(--font-mono);
  letter-spacing: .04em;
}

.badge-dot {
  width: 6px; height: 6px;
  background: var(--accent-2);
  border-radius: 50%;
  animation: pulse 2s ease-in-out infinite;
  flex-shrink: 0;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50%       { opacity: .5; transform: scale(.7); }
}

.hero-title {
  color: var(--white);
  margin-bottom: 22px;
  letter-spacing: -.02em;
}

.title-accent {
  color: transparent;
  background: linear-gradient(135deg, var(--primary), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.12rem;
  color: var(--text-light);
  max-width: 540px;
  margin: 0 auto 50px;
  line-height: 1.7;
}

/* Level cards in hero */
.hero-level-cards {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  max-width: 820px;
  margin: 0 auto;
}

.level-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 16px 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition), background var(--transition);
  cursor: pointer;
}

.level-card:hover {
  border-color: var(--primary);
  background: var(--bg-card-hover);
  transform: translateY(-6px);
  box-shadow: var(--shadow-hover);
}

.level-card-icon {
  width: 44px; height: 44px;
  color: var(--primary);
  opacity: .8;
  transition: opacity var(--transition), color var(--transition);
}
.level-card:hover .level-card-icon { opacity: 1; color: var(--accent-2); }

.level-card-num {
  font-family: var(--font-display);
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--white);
  line-height: 1;
}

.level-card-label {
  font-size: .82rem;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: .08em;
}

.level-card-arrow {
  font-size: .95rem;
  color: var(--primary);
  margin-top: 4px;
  transition: transform var(--transition);
}
.level-card:hover .level-card-arrow { transform: translateX(4px); }

/* Scroll hint */
.hero-scroll-hint {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  z-index: 1;
}
.hero-scroll-hint span {
  font-size: .72rem;
  color: var(--text-muted);
  letter-spacing: .12em;
  text-transform: uppercase;
  font-family: var(--font-mono);
}
.scroll-dot {
  width: 6px; height: 6px;
  background: var(--primary);
  border-radius: 50%;
  animation: scrollBounce 1.8s ease-in-out infinite;
}
@keyframes scrollBounce {
  0%, 100% { transform: translateY(0); opacity: 1; }
  50%       { transform: translateY(8px); opacity: .4; }
}

/* ----------------------------------------------------------------
   6. NIVELES
---------------------------------------------------------------- */
.niveles-section { background: var(--bg-section); }

.niveles-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.nivel-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  transition: border-color var(--transition), transform var(--transition), box-shadow var(--transition);
  position: relative;
  overflow: hidden;
}

.nivel-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--accent-2));
  opacity: 0;
  transition: opacity var(--transition);
}

.nivel-card:hover {
  border-color: var(--border-glow);
  transform: translateY(-6px);
  box-shadow: var(--shadow-hover);
}
.nivel-card:hover::before { opacity: 1; }

.nivel-card-header {
  display: flex;
  align-items: baseline;
  gap: 6px;
}

.nivel-num {
  font-family: var(--font-display);
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--primary);
  line-height: 1;
}

.nivel-tag {
  font-family: var(--font-mono);
  font-size: .72rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: .1em;
}

.nivel-icon {
  width: 52px; height: 52px;
  color: var(--primary);
  opacity: .7;
  transition: opacity var(--transition);
}
.nivel-card:hover .nivel-icon { opacity: 1; }

.nivel-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--white);
}

.nivel-desc {
  font-size: .9rem;
  color: var(--text-light);
  line-height: 1.65;
  flex: 1;
}

.btn-nivel {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: .88rem;
  font-weight: 600;
  color: var(--primary);
  padding: 10px 18px;
  border: 1px solid rgba(14,165,233,.25);
  border-radius: var(--radius-sm);
  transition: background var(--transition), border-color var(--transition), color var(--transition);
  width: fit-content;
}
.btn-nivel:hover {
  background: rgba(14,165,233,.1);
  border-color: var(--primary);
  color: var(--accent-2);
}

/* ----------------------------------------------------------------
   7. CONTENIDOS
---------------------------------------------------------------- */
.contenidos-section {
  background: var(--bg-dark);
}

.contenidos-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.contenido-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  cursor: default;
  transition: border-color var(--transition), transform var(--transition), box-shadow var(--transition);
}

.contenido-card:hover {
  border-color: rgba(249,115,22,.3);
  transform: translateY(-4px);
  box-shadow: 0 8px 30px rgba(249,115,22,.1);
}

.contenido-icon {
  width: 44px; height: 44px;
  color: var(--accent);
  opacity: .85;
}

.contenido-card h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--white);
}

.contenido-card p {
  font-size: .88rem;
  color: var(--text-light);
  line-height: 1.6;
  flex: 1;
}

.contenido-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 4px;
}

.contenido-tags span {
  font-size: .72rem;
  font-family: var(--font-mono);
  color: var(--accent-2);
  background: rgba(34,211,238,.08);
  border: 1px solid rgba(34,211,238,.18);
  border-radius: 100px;
  padding: 3px 10px;
  letter-spacing: .06em;
}

/* ----------------------------------------------------------------
   8. MATERIAL EDUCATIVO
---------------------------------------------------------------- */
.material-section { background: var(--bg-section); }

.material-upload-banner {
  display: flex;
  align-items: center;
  gap: 20px;
  background: linear-gradient(135deg, rgba(14,165,233,.12) 0%, rgba(34,211,238,.06) 100%);
  border: 1px solid rgba(14,165,233,.25);
  border-radius: var(--radius-lg);
  padding: 24px 28px;
  margin-bottom: 36px;
}

.upload-icon {
  width: 48px; height: 48px;
  color: var(--primary);
  flex-shrink: 0;
}

.upload-text {
  flex: 1;
}
.upload-text strong { font-size: 1rem; color: var(--white); }
.upload-text p { font-size: .88rem; color: var(--text-light); margin-top: 3px; }

.btn-upload {
  flex-shrink: 0;
  background: var(--primary);
  color: var(--white);
  font-size: .88rem;
  font-weight: 600;
  padding: 12px 22px;
  border-radius: var(--radius-sm);
  transition: background var(--transition), transform var(--transition);
}
.btn-upload:hover {
  background: var(--accent-2);
  transform: translateY(-2px);
}

/* Filters */
.material-filters {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 30px;
}

.filter-btn {
  font-size: .85rem;
  font-weight: 500;
  color: var(--text-muted);
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 100px;
  padding: 7px 18px;
  transition: all var(--transition);
}
.filter-btn:hover { color: var(--text); border-color: rgba(255,255,255,.15); }
.filter-btn.active {
  color: var(--primary);
  background: rgba(14,165,233,.1);
  border-color: rgba(14,165,233,.35);
}

/* Material grid */
.material-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.material-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  position: relative;
  overflow: hidden;
  transition: border-color var(--transition), transform var(--transition), box-shadow var(--transition);
}
.material-card:hover {
  border-color: var(--border-glow);
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.material-type-badge {
  position: absolute;
  top: 16px; right: 16px;
  font-size: .68rem;
  font-family: var(--font-mono);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: .1em;
  padding: 4px 10px;
  border-radius: 100px;
}
.material-type-badge.guia        { background: rgba(14,165,233,.12); color: var(--primary); border: 1px solid rgba(14,165,233,.2); }
.material-type-badge.evaluacion  { background: rgba(249,115,22,.12); color: var(--accent);  border: 1px solid rgba(249,115,22,.2); }
.material-type-badge.presentacion { background: rgba(34,211,238,.12); color: var(--accent-2); border: 1px solid rgba(34,211,238,.2); }

.material-icon {
  width: 40px; height: 40px;
  color: var(--text-muted);
}

.material-info { flex: 1; }
.material-info h3 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--white);
  margin-bottom: 6px;
  padding-right: 80px;
}
.material-info p {
  font-size: .85rem;
  color: var(--text-light);
  line-height: 1.55;
}

.material-meta {
  display: flex;
  gap: 12px;
  margin-top: 10px;
}
.meta-level {
  font-size: .72rem;
  font-family: var(--font-mono);
  color: var(--accent-2);
  background: rgba(34,211,238,.08);
  border: 1px solid rgba(34,211,238,.15);
  padding: 3px 9px;
  border-radius: 100px;
}
.meta-pages {
  font-size: .72rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  padding: 3px 0;
}

.btn-download {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(14,165,233,.1);
  color: var(--primary);
  border: 1px solid rgba(14,165,233,.2);
  border-radius: var(--radius-sm);
  padding: 10px 16px;
  font-size: .85rem;
  font-weight: 600;
  width: fit-content;
  transition: all var(--transition);
}
.btn-download:hover {
  background: var(--primary);
  color: var(--white);
  border-color: var(--primary);
}

/* Cards hidden by filter */
.material-card.hidden {
  display: none;
}

/* ----------------------------------------------------------------
   9. RECURSOS DIGITALES
---------------------------------------------------------------- */
.recursos-section { background: var(--bg-dark); }

.recursos-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.recurso-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  display: flex;
  align-items: center;
  gap: 20px;
  cursor: pointer;
  position: relative;
  transition: border-color var(--transition), transform var(--transition), box-shadow var(--transition);
  overflow: hidden;
}
.recurso-card::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, transparent 60%, rgba(14,165,233,.04));
  pointer-events: none;
}
.recurso-card:hover {
  border-color: var(--border-glow);
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.recurso-logo {
  width: 56px; height: 56px;
  flex-shrink: 0;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 10px;
}
.recurso-logo.geogebra   { background: rgba(14,165,233,.12); color: var(--primary); }
.recurso-logo.desmos     { background: rgba(34,211,238,.12); color: var(--accent-2); }
.recurso-logo.calc       { background: rgba(249,115,22,.12); color: var(--accent); }
.recurso-logo.videos     { background: rgba(239,68,68,.12);  color: #ef4444; }

.recurso-info { flex: 1; }
.recurso-info h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--white);
  margin-bottom: 6px;
}
.recurso-info p {
  font-size: .88rem;
  color: var(--text-light);
  line-height: 1.55;
}

.recurso-ext {
  font-size: 1.2rem;
  color: var(--text-muted);
  flex-shrink: 0;
  transition: color var(--transition), transform var(--transition);
}
.recurso-card:hover .recurso-ext {
  color: var(--primary);
  transform: translate(3px, -3px);
}

/* ----------------------------------------------------------------
   10. CONTACTO
---------------------------------------------------------------- */
.contacto-section { background: var(--bg-section); }

.contacto-inner {
  max-width: 680px;
  margin: 0 auto;
  text-align: center;
}
.contacto-inner .section-title { margin-bottom: 10px; }
.contacto-inner .section-desc  { margin-bottom: 40px; }

.contacto-form {
  text-align: left;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.form-group label {
  font-size: .85rem;
  font-weight: 500;
  color: var(--text-light);
  letter-spacing: .02em;
}

.form-group input,
.form-group textarea {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  padding: 13px 16px;
  font-size: .95rem;
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
  resize: none;
}
.form-group input::placeholder,
.form-group textarea::placeholder { color: var(--text-muted); }
.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(14,165,233,.1);
}

.btn-enviar {
  background: linear-gradient(135deg, var(--primary), var(--accent-2));
  color: var(--white);
  font-size: 1rem;
  font-weight: 700;
  padding: 15px 36px;
  border-radius: var(--radius-sm);
  transition: opacity var(--transition), transform var(--transition);
  align-self: center;
}
.btn-enviar:hover { opacity: .88; transform: translateY(-2px); }

/* ----------------------------------------------------------------
   11. FOOTER
---------------------------------------------------------------- */
.footer {
  background: var(--bg-dark);
  border-top: 1px solid var(--border);
  padding: 64px 0 32px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 2fr;
  gap: 40px;
  margin-bottom: 48px;
}

.footer-brand p {
  font-size: .9rem;
  color: var(--text-muted);
  margin-top: 16px;
  line-height: 1.65;
  max-width: 260px;
}

.footer-logo { margin-bottom: 4px; }

.footer-nav h4 { margin-bottom: 18px; }

.footer-nav ul {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-nav a {
  font-size: .9rem;
  color: var(--text-muted);
  transition: color var(--transition);
}
.footer-nav a:hover { color: var(--primary); }

.footer-mineduc h4 { margin-bottom: 14px; }
.footer-mineduc p {
  font-size: .88rem;
  color: var(--text-muted);
  line-height: 1.65;
}
.footer-link-ext {
  display: inline-block;
  margin-top: 14px;
  font-size: .85rem;
  font-family: var(--font-mono);
  color: var(--primary);
  transition: color var(--transition);
}
.footer-link-ext:hover { color: var(--accent-2); }

.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 28px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}
.footer-bottom p,
.footer-credit {
  font-size: .82rem;
  color: var(--text-muted);
}
.footer-credit a {
  color: var(--text-muted);
  text-decoration: underline;
  text-underline-offset: 3px;
}
.footer-credit a:hover { color: var(--primary); }

/* ----------------------------------------------------------------
   12. RESPONSIVE
---------------------------------------------------------------- */
@media (max-width: 1024px) {
  .niveles-grid       { grid-template-columns: repeat(2, 1fr); }
  .contenidos-grid    { grid-template-columns: repeat(2, 1fr); }
  .footer-grid        { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  :root { --nav-h: 60px; }

  .hamburger { display: flex; }

  .nav-links {
    position: fixed;
    top: var(--nav-h);
    right: 0;
    bottom: 0;
    width: 280px;
    flex-direction: column;
    align-items: flex-start;
    gap: 2px;
    background: rgba(11,15,26,.97);
    backdrop-filter: blur(20px);
    padding: 20px 16px;
    border-left: 1px solid var(--border);
    transform: translateX(100%);
    transition: transform var(--transition);
    z-index: 1000;
  }
  .nav-links.open { transform: translateX(0); }
  .nav-links li { width: 100%; }
  .nav-link { display: block; padding: 12px 16px; font-size: 1rem; border-radius: var(--radius-sm); }

  .hero-level-cards { grid-template-columns: repeat(2, 1fr); }

  .niveles-grid    { grid-template-columns: 1fr; }
  .contenidos-grid { grid-template-columns: 1fr; }
  .material-grid   { grid-template-columns: 1fr; }
  .recursos-grid   { grid-template-columns: 1fr; }

  .footer-grid  { grid-template-columns: 1fr; gap: 32px; }
  .footer-bottom { flex-direction: column; }

  .form-row { grid-template-columns: 1fr; }

  .material-upload-banner { flex-direction: column; text-align: center; }
}

@media (max-width: 480px) {
  .section { padding: 70px 0; }
  .hero-level-cards { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .level-card { padding: 18px 12px; }
  .level-card-num { font-size: 1.5rem; }
  .recurso-card { flex-direction: column; text-align: center; }
}

/* ----------------------------------------------------------------
   13. ACCESSIBILITY & FOCUS
---------------------------------------------------------------- */
:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
  border-radius: 4px;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: .01ms !important;
    transition-duration: .01ms !important;
  }
}