/* LovU — sistema visual propio: blanco, minimalista y cómodo para sesiones largas.
   Azul navy como acento, Inter en todo; el pixel art vive SOLO en el avatar. */
:root {
  --bg: #FFFFFF;
  --bg-2: #F6F8FB;
  --bg-3: #EEF2F7;
  --linea: #E5E9F0;
  --texto: #0F172A;
  --texto-2: #5B6B82;
  --texto-3: #8A98AD;
  --navy: #1E4D8C;
  --navy-2: #2F6FC4;
  --navy-suave: #E8F0FB;
  --navy-900: #0A1628;
  --ok: #1B9E5A;   --ok-bg: #E7F7EE;
  --mal: #D64545;  --mal-bg: #FDECEC;
  --ambar: #B47A00; --ambar-bg: #FFF4D6;
  --radio: 14px; --radio-sm: 10px;
  --sombra: 0 1px 2px rgba(15, 23, 42, .05), 0 10px 30px -18px rgba(15, 23, 42, .25);
  --sombra-hover: 0 2px 4px rgba(15, 23, 42, .06), 0 16px 36px -18px rgba(15, 23, 42, .3);
  --fuente: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  --rapido: 160ms cubic-bezier(.2, .7, .3, 1);
  --suave: 320ms cubic-bezier(.2, .7, .2, 1);
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg); color: var(--texto); font-family: var(--fuente);
  font-size: 16px; line-height: 1.6; -webkit-font-smoothing: antialiased; min-height: 100vh;
}
a { color: var(--navy-2); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }
button, input, select, textarea { font-family: inherit; font-size: inherit; color: inherit; }
img { max-width: 100%; }
::selection { background: var(--navy-suave); }

/* ---- movimiento ---- */
@keyframes aparecer { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
@keyframes pulso { 0%, 100% { opacity: .45; } 50% { opacity: 1; } }
@keyframes pop { 0% { transform: scale(1); } 40% { transform: scale(1.015); } 100% { transform: scale(1); } }
@keyframes sacudir { 0%, 100% { transform: translateX(0); } 25% { transform: translateX(-4px); } 75% { transform: translateX(4px); } }
main > * { animation: aparecer var(--suave) both; }
main > *:nth-child(2) { animation-delay: 40ms; } main > *:nth-child(3) { animation-delay: 80ms; }
main > *:nth-child(4) { animation-delay: 120ms; } main > *:nth-child(n+5) { animation-delay: 160ms; }
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { animation: none !important; transition: none !important; } }

.cargando { color: var(--texto-3); padding: 48px 0; text-align: center; animation: pulso 1.2s ease-in-out infinite; }

/* ---- layout ---- */
.barra {
  display: flex; align-items: center; gap: 18px; flex-wrap: wrap; padding: 14px 24px;
  background: rgba(255, 255, 255, .86); backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--linea); position: sticky; top: 0; z-index: 5;
}
.logo { font-weight: 800; font-size: 20px; letter-spacing: -.02em; color: var(--texto); }
.logo span { color: var(--navy-2); }
.logo:hover { text-decoration: none; }
.nav { display: flex; gap: 2px; flex-wrap: wrap; margin-left: auto; }
.nav a {
  font-size: 14px; font-weight: 500; color: var(--texto-2); padding: 8px 12px; border-radius: 999px;
  transition: background var(--rapido), color var(--rapido);
}
.nav a:hover { background: var(--bg-2); color: var(--texto); text-decoration: none; }
.nav a.activa { background: var(--navy-suave); color: var(--navy); }
main { max-width: 980px; margin: 0 auto; padding: 32px 24px 96px; }
h1, h2, h3 { line-height: 1.3; margin: 0 0 14px; letter-spacing: -.015em; }
h1 { font-size: 28px; font-weight: 700; }
h2 { font-size: 18px; font-weight: 650; margin-top: 36px; }
h3 { font-size: 15px; font-weight: 600; color: var(--texto-2); }
p { margin: 0 0 12px; }
.sub { color: var(--texto-2); font-size: 14px; }

/* ---- componentes ---- */
.caja {
  background: var(--bg); border: 1px solid var(--linea); border-radius: var(--radio); box-shadow: var(--sombra);
  padding: 22px; margin-bottom: 18px;
}
.caja.plana { box-shadow: none; background: var(--bg-2); border-color: transparent; }
.fila { display: flex; gap: 12px; flex-wrap: wrap; align-items: center; }
.grid { display: grid; gap: 14px; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); }
.grid.ancha { grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px; font-weight: 600; font-size: 15px;
  padding: 11px 18px; border-radius: var(--radio-sm); border: 1px solid transparent; cursor: pointer; user-select: none;
  background: var(--navy); color: #fff; line-height: 1.2; text-decoration: none;
  transition: transform var(--rapido), box-shadow var(--rapido), background var(--rapido), border-color var(--rapido);
}
.btn:hover { background: var(--navy-2); transform: translateY(-1px); box-shadow: var(--sombra-hover); text-decoration: none; }
.btn:active { transform: translateY(0) scale(.985); box-shadow: none; }
.btn.sec { background: var(--bg); color: var(--texto); border-color: var(--linea); }
.btn.sec:hover { background: var(--bg-2); }
.btn.ok { background: var(--ok); } .btn.ok:hover { background: #17874d; }
.btn.mal { background: var(--mal); } .btn.mal:hover { background: #bf3a3a; }
.btn.ambar { background: var(--ambar); } .btn.ambar:hover { background: #9a6800; }
.btn.mini { font-size: 13px; padding: 8px 12px; }
.btn[disabled] { opacity: .45; cursor: not-allowed; transform: none; box-shadow: none; }
.btn.block { display: flex; width: 100%; }
input[type=text], input[type=password], input[type=number], select, textarea {
  background: var(--bg); border: 1px solid var(--linea); border-radius: var(--radio-sm); padding: 11px 14px; width: 100%;
  transition: border-color var(--rapido), box-shadow var(--rapido);
}
input:focus, select:focus, textarea:focus { outline: none; border-color: var(--navy-2); box-shadow: 0 0 0 4px var(--navy-suave); }
label { display: block; font-size: 13px; font-weight: 500; color: var(--texto-2); margin-bottom: 6px; }
.chip {
  display: inline-flex; align-items: center; gap: 6px; font-size: 13px; padding: 4px 10px; border-radius: 999px;
  background: var(--bg-2); color: var(--texto-2); margin: 2px 6px 2px 0; border: 1px solid transparent;
}
.chip.ok { background: var(--ok-bg); color: var(--ok); }
.chip.mal { background: var(--mal-bg); color: var(--mal); }
.chip.ambar { background: var(--ambar-bg); color: var(--ambar); }
a.chip { color: var(--texto); transition: background var(--rapido); } a.chip:hover { background: var(--navy-suave); text-decoration: none; }
.tag { font-size: 12px; font-weight: 600; letter-spacing: .06em; text-transform: uppercase; color: var(--texto-3); }
.num { font-size: 30px; font-weight: 700; letter-spacing: -.02em; line-height: 1.1; }
.num.sm { font-size: 15px; font-weight: 500; color: var(--texto-2); letter-spacing: 0; }
.aviso {
  border-radius: var(--radio-sm); background: var(--ambar-bg); color: #6e4a00; padding: 12px 16px; margin-bottom: 12px; font-size: 14px;
}
.aviso a { color: inherit; font-weight: 600; }
.aviso.mal { background: var(--mal-bg); color: #8a2a2a; }
.aviso.ok { background: var(--ok-bg); color: #135f38; }
.error { color: var(--mal); font-size: 14px; }
hr { border: 0; border-top: 1px solid var(--linea); margin: 20px 0; }
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 10px 10px; border-bottom: 1px solid var(--linea); vertical-align: top; }
th { font-size: 12px; font-weight: 600; letter-spacing: .04em; text-transform: uppercase; color: var(--texto-3); }
tr:last-child td { border-bottom: 0; }
.tabla-wrap { overflow-x: auto; border: 1px solid var(--linea); border-radius: var(--radio); background: var(--bg); }
details summary { list-style: none; } details summary::-webkit-details-marker { display: none; }

/* ---- barra de progreso: base (diagnóstico) + ganado (práctica) ---- */
.pbar { position: relative; height: 8px; border-radius: 999px; background: var(--bg-3); overflow: hidden; }
.pbar i { position: absolute; left: 0; top: 0; bottom: 0; border-radius: 999px; transition: width .7s cubic-bezier(.2, .7, .2, 1); }
.pbar i.on { background: var(--navy-2); }
.pbar i.base { background: var(--navy); }
.pbar.grande { height: 12px; }
.pct { font-variant-numeric: tabular-nums; font-weight: 600; min-width: 44px; text-align: right; color: var(--texto-2); }

/* ---- mapa ---- */
.tile {
  display: block; background: var(--bg); border: 1px solid var(--linea); border-radius: var(--radio); padding: 16px; color: inherit;
  transition: transform var(--rapido), box-shadow var(--rapido), border-color var(--rapido);
}
.tile:hover { transform: translateY(-2px); box-shadow: var(--sombra-hover); border-color: #D5DDE8; text-decoration: none; }
.tile .nombre { font-weight: 600; font-size: 15px; margin-bottom: 10px; min-height: 2.6em; line-height: 1.35; }
.tile .meta { font-size: 13px; color: var(--texto-2); margin-top: 8px; display: flex; justify-content: space-between; }
.tile.vacio { opacity: .55; }
.modulo-cab { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin: 28px 0 12px; }
.modulo-cab h2 { margin: 0; }

/* ---- reactivo ---- */
.reactivo .enunciado { font-size: 17px; line-height: 1.65; margin-bottom: 18px; white-space: pre-wrap; }
.opciones { display: grid; gap: 10px; }
.opcion {
  display: flex; gap: 14px; align-items: flex-start; text-align: left; cursor: pointer; width: 100%;
  background: var(--bg); border: 1px solid var(--linea); border-radius: var(--radio-sm); padding: 13px 16px; color: var(--texto);
  transition: border-color var(--rapido), background var(--rapido), transform var(--rapido), box-shadow var(--rapido);
}
.opcion:hover { border-color: var(--navy-2); background: var(--navy-suave); }
.opcion .letra {
  flex: 0 0 26px; width: 26px; height: 26px; border-radius: 8px; display: grid; place-items: center;
  font-size: 12px; font-weight: 700; background: var(--bg-2); color: var(--texto-2); transition: background var(--rapido), color var(--rapido);
}
.opcion:hover .letra { background: #fff; color: var(--navy); }
.opcion.elegida { border-color: var(--navy-2); box-shadow: 0 0 0 3px var(--navy-suave); }
.opcion.correcta { border-color: var(--ok); background: var(--ok-bg); animation: pop .35s ease; }
.opcion.correcta .letra { background: var(--ok); color: #fff; }
.opcion.incorrecta { border-color: var(--mal); background: var(--mal-bg); animation: sacudir .3s ease; }
.opcion.incorrecta .letra { background: var(--mal); color: #fff; }
.opcion[disabled] { cursor: default; }
.opcion[disabled]:hover { border-color: var(--linea); background: var(--bg); }
.opcion.correcta[disabled]:hover { border-color: var(--ok); background: var(--ok-bg); }
.opcion.incorrecta[disabled]:hover { border-color: var(--mal); background: var(--mal-bg); }
.explicacion { margin-top: 18px; padding: 16px 18px; background: var(--bg-2); border-radius: var(--radio-sm); animation: aparecer var(--suave) both; }
.explicacion .tit { font-size: 12px; font-weight: 700; letter-spacing: .06em; margin-bottom: 8px; }
.explicacion .tit.ok { color: var(--ok); }
.explicacion .tit.mal { color: var(--mal); }
.dist { margin-top: 10px; font-size: 14px; color: var(--texto-2); }
.dist b { color: var(--texto); }

/* ---- flashcards (volteo 3D) ---- */
.flash { perspective: 1200px; cursor: pointer; min-height: 190px; }
.flash .carta { position: relative; min-height: 190px; transform-style: preserve-3d; transition: transform .5s cubic-bezier(.2, .7, .2, 1); }
.flash.volteada .carta { transform: rotateY(180deg); }
.flash .cara {
  position: absolute; inset: 0; backface-visibility: hidden; -webkit-backface-visibility: hidden;
  border-radius: var(--radio); border: 1px solid var(--linea); background: var(--bg); box-shadow: var(--sombra);
  padding: 24px; display: flex; align-items: center; justify-content: center; text-align: center; font-size: 17px; white-space: pre-wrap;
}
.flash .cara.reverso { transform: rotateY(180deg); background: var(--navy-suave); border-color: transparent; }
.flash-botones { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; margin-top: 14px; animation: aparecer var(--suave) both; }

/* ---- simulacro ---- */
.cuadricula { display: grid; grid-template-columns: repeat(auto-fill, minmax(40px, 1fr)); gap: 6px; }
.cuadricula button {
  font-size: 13px; font-weight: 600; padding: 9px 0; background: var(--bg); border: 1px solid var(--linea); border-radius: 8px;
  color: var(--texto-2); cursor: pointer; transition: background var(--rapido), border-color var(--rapido), color var(--rapido);
}
.cuadricula button:hover { border-color: var(--navy-2); color: var(--navy); }
.cuadricula button.resp { background: var(--navy-suave); color: var(--navy); border-color: transparent; }
.cuadricula button.actual { box-shadow: 0 0 0 3px var(--navy-suave); border-color: var(--navy-2); }
.timer { font-size: 18px; font-weight: 700; font-variant-numeric: tabular-nums; }
.timer.urgente { color: var(--mal); animation: pulso 1s ease-in-out infinite; }
.sticky { position: sticky; top: 64px; z-index: 4; }

/* ---- chat ---- */
.chat-log { display: flex; flex-direction: column; gap: 12px; min-height: 320px; max-height: 60vh; overflow-y: auto; padding: 4px 2px; }
.msg { max-width: 84%; padding: 12px 16px; border-radius: 16px; animation: aparecer var(--suave) both; line-height: 1.55; }
.msg.yo { align-self: flex-end; background: var(--navy); color: #fff; border-bottom-right-radius: 6px; }
.msg.tutor { align-self: flex-start; background: var(--bg-2); border-bottom-left-radius: 6px; }
.msg .md p:last-child { margin: 0; }
.chat-form { display: flex; gap: 10px; margin-top: 14px; align-items: flex-end; }
.chat-form textarea { min-height: 54px; resize: vertical; }

/* ---- markdown de estudio ---- */
.md { font-size: 16px; line-height: 1.7; }
.md h1, .md h2, .md h3 { font-weight: 700; margin: 22px 0 8px; letter-spacing: -.01em; }
.md h1 { font-size: 22px; } .md h2 { font-size: 19px; color: var(--navy); } .md h3 { font-size: 16px; }
.md ul, .md ol { padding-left: 24px; margin: 0 0 12px; }
.md li { margin: 4px 0; }
.md code { background: var(--bg-3); padding: 1px 6px; border-radius: 6px; font-size: 14px; }
.md pre { background: var(--bg-2); border-radius: var(--radio-sm); padding: 14px; overflow-x: auto; }
.md table { margin: 8px 0 16px; }
.md blockquote { border-left: 3px solid var(--navy-2); margin: 0 0 12px; padding: 4px 14px; color: var(--texto-2); }
.md b { font-weight: 650; }

/* ---- recursos ---- */
.figura { background: var(--bg); border: 1px solid var(--linea); border-radius: var(--radio); padding: 10px; overflow: hidden; }
.figura img { display: block; width: 100%; border-radius: 8px; background: #fff; }
.figura .pie { font-size: 12px; color: var(--texto-3); margin-top: 8px; line-height: 1.4; }
.video { position: relative; padding-top: 56.25%; border-radius: var(--radio); overflow: hidden; background: var(--bg-3); }
.video iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }

/* ---- avatar: el único lugar con pixel art ---- */
.avatar { width: 96px; height: 96px; border-radius: 20px; background: var(--navy-suave); flex: 0 0 auto; overflow: hidden; display: grid; place-items: center; }
.avatar canvas, .avatar img { width: 84px; height: 84px; image-rendering: pixelated; image-rendering: crisp-edges; display: block; object-fit: contain; }
.hablado { font-size: 15px; background: var(--bg-2); border-radius: 16px; border-top-left-radius: 4px; padding: 12px 16px; }

/* ---- login ---- */
.login { max-width: 400px; margin: 14vh auto; }
.login h1 { font-size: 34px; text-align: center; margin-bottom: 6px; font-weight: 800; letter-spacing: -.03em; }
.login .sub { text-align: center; margin-bottom: 24px; }

.oculto { display: none !important; }
.kbd { font-size: 12px; color: var(--texto-3); }
@media (max-width: 640px) {
  .barra { padding: 12px 16px; gap: 10px; }
  .nav { flex-wrap: nowrap; overflow-x: auto; width: 100%; margin-left: 0; scrollbar-width: none; -webkit-overflow-scrolling: touch; }
  .nav::-webkit-scrollbar { display: none; }
  .nav a { font-size: 13px; padding: 7px 10px; white-space: nowrap; }
  main { padding: 20px 16px 80px; }
  h1 { font-size: 24px; }
  .flash-botones { grid-template-columns: repeat(2, 1fr); }
  .msg { max-width: 94%; }
  .num { font-size: 26px; }
}