/* Lyz Math: matemáticas resueltas paso a paso. Misma estética que la app Lyz Math (fondo oscuro con brillos,
   tarjetas de cristal, Inter y degradados), pero en verde. */
@font-face { font-family: "Inter"; src: url("fonts/inter.woff2") format("woff2"); font-weight: 100 900; font-display: swap; }
@font-face { font-family: "JetBrains Mono"; src: url("fonts/jetbrains-mono.woff2") format("woff2"); font-weight: 100 800; font-display: swap; }

:root {
  --a-rgb: 16, 185, 129;    /* esmeralda */
  --m-rgb: 52, 211, 153;
  --b-rgb: 163, 230, 53;    /* lima */
  --fondo: #070d0a;
  --superficie: rgba(255, 255, 255, 0.04);
  --superficie-2: rgba(255, 255, 255, 0.07);
  --superficie-solida: #0e1813;
  --borde: rgba(255, 255, 255, 0.085);
  --borde-fuerte: rgba(255, 255, 255, 0.16);
  --texto: #eaf3ee;
  --texto-2: #a7bdb1;
  --texto-3: #6f897b;
  --acento: rgb(var(--a-rgb));
  --acento-claro: rgb(var(--m-rgb));
  --grad: linear-gradient(135deg, rgb(var(--a-rgb)) 0%, rgb(var(--m-rgb)) 55%, rgb(var(--b-rgb)) 100%);
  --grad-suave: linear-gradient(135deg, rgba(var(--a-rgb), 0.16), rgba(var(--b-rgb), 0.08));
  --ok: #34d399;
  --sombra: 0 18px 50px rgba(0, 0, 0, 0.38);
  --radio: 20px;
  --sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, Consolas, monospace;
  color-scheme: dark;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body { margin: 0; min-height: 100vh; display: flex; flex-direction: column; background: var(--fondo); color: var(--texto);
  font: 16px/1.6 var(--sans); -webkit-font-smoothing: antialiased; }
body::before { content: ""; position: fixed; inset: 0; z-index: -1; pointer-events: none;
  background: radial-gradient(900px 600px at 8% -10%, rgba(var(--a-rgb), 0.2), transparent 60%),
    radial-gradient(800px 500px at 100% 0%, rgba(var(--b-rgb), 0.1), transparent 60%),
    radial-gradient(700px 500px at 60% 120%, rgba(var(--a-rgb), 0.14), transparent 60%); }
body > main { flex: 1 0 auto; }
a { color: var(--acento-claro); text-underline-offset: 3px; }
a:hover { color: #6ee7b7; }
:focus-visible { outline: 2px solid var(--acento-claro); outline-offset: 2px; }
.wrap { max-width: 1120px; margin: 0 auto; padding: 0 18px; }
.skip { position: absolute; left: -9999px; top: 8px; z-index: 20; background: var(--acento); color: #03140c; padding: 8px 14px; border-radius: 10px; font-weight: 700; }
.skip:focus { left: 8px; }
h1, h2, h3 { line-height: 1.15; letter-spacing: -0.025em; font-weight: 800; }
h1 { font-size: clamp(2rem, 5vw, 3.1rem); margin: 0 0 14px; }
h2 { font-size: clamp(1.4rem, 3vw, 1.85rem); margin: 44px 0 16px; }
h3 { font-size: 1.1rem; margin: 0 0 6px; }
.grad-txt { background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.lead { font-size: 1.12rem; color: var(--texto-2); max-width: 720px; margin: 0 0 22px; }
.muted { color: var(--texto-2); }

/* ---------- Cabecera ---------- */
header.site { position: sticky; top: 0; z-index: 10; background: rgba(7, 13, 10, 0.72); border-bottom: 1px solid var(--borde);
  -webkit-backdrop-filter: blur(16px) saturate(1.4); backdrop-filter: blur(16px) saturate(1.4); }
header.site .wrap { display: flex; align-items: center; gap: 14px; min-height: 66px; }
.logo { display: inline-flex; align-items: center; gap: 10px; color: var(--texto); text-decoration: none; font-weight: 800; font-size: 1.15rem; letter-spacing: -0.02em; }
.logo:hover { color: var(--texto); }
.logo img { width: 36px; height: 36px; }
.logo span { color: var(--texto-2); font-weight: 600; }
nav.top { display: flex; gap: 2px; margin-left: auto; align-items: center; flex-wrap: wrap; }
nav.top a { color: var(--texto-2); text-decoration: none; padding: 7px 12px; border-radius: 10px; font-weight: 600; font-size: 0.94rem; }
nav.top a:hover, nav.top a.on { color: var(--texto); background: var(--superficie-2); }
nav.top a.btn { margin-left: 6px; color: #03140c; }
@media (max-width: 860px) { nav.top a:not(.btn):not(.keep) { display: none; } }

/* ---------- Botones ---------- */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 10px; border: 0; border-radius: 14px; padding: 12px 20px;
  background: var(--grad); color: #03140c; font: 700 1rem var(--sans); text-decoration: none; cursor: pointer;
  box-shadow: 0 8px 24px rgba(var(--a-rgb), 0.35); transition: transform 0.15s, box-shadow 0.15s; }
.btn:hover { color: #03140c; transform: translateY(-1px); box-shadow: 0 12px 32px rgba(var(--a-rgb), 0.45); }
.btn.small { padding: 8px 14px; font-size: 0.9rem; border-radius: 11px; }
.btn.ghost { background: var(--superficie); color: var(--texto); border: 1px solid var(--borde-fuerte); box-shadow: none; }
.btn.ghost:hover { color: var(--texto); background: var(--superficie-2); }
.btn svg { width: 20px; height: 20px; flex: none; }
.play-btn { padding: 12px 22px 12px 18px; text-align: left; line-height: 1.15; }
.play-btn small { display: block; font-size: 0.72rem; font-weight: 600; opacity: 0.8; }
.play-btn b { font-size: 1.08rem; }

/* ---------- Tarjetas ---------- */
.card { background: var(--superficie); border: 1px solid var(--borde); border-radius: var(--radio); padding: 22px;
  -webkit-backdrop-filter: blur(18px); backdrop-filter: blur(18px); }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 14px; }
.tile { display: flex; gap: 14px; align-items: flex-start; color: var(--texto); text-decoration: none; transition: border-color 0.15s, transform 0.15s, background 0.15s; }
.tile:hover { color: var(--texto); border-color: rgba(var(--a-rgb), 0.55); background: var(--superficie-2); transform: translateY(-2px); }
.tile .ico { flex: 0 0 46px; height: 46px; border-radius: 14px; display: grid; place-items: center; background: var(--grad-suave);
  border: 1px solid rgba(var(--a-rgb), 0.3); color: var(--acento-claro); font: 700 1.05rem var(--mono); }
.tile p { margin: 0; color: var(--texto-2); font-size: 0.9rem; line-height: 1.45; }
.tile .n { display: inline-block; margin-top: 8px; font-size: 0.78rem; font-weight: 700; color: var(--acento-claro); }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip { display: inline-flex; align-items: center; gap: 6px; height: 32px; padding: 0 13px; border-radius: 999px; border: 1px solid var(--borde);
  background: var(--superficie); color: var(--texto-2); font-size: 0.85rem; font-weight: 600; text-decoration: none; }
a.chip:hover { color: var(--texto); border-color: var(--acento); background: var(--grad-suave); }
.chip.ok { color: var(--ok); border-color: rgba(52, 211, 153, 0.4); background: rgba(52, 211, 153, 0.1); }

/* ---------- Portada ---------- */
.hero { display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 40px; align-items: center; padding: 56px 0 30px; }
.hero h1 { font-size: clamp(2.3rem, 5.6vw, 3.7rem); }
.eyebrow { display: inline-flex; align-items: center; gap: 8px; padding: 5px 13px; border-radius: 999px; background: var(--grad-suave);
  border: 1px solid rgba(var(--a-rgb), 0.3); color: var(--acento-claro); font-size: 0.82rem; font-weight: 700; margin: 0 0 18px; }
.hero .acciones { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }
.hero .pista { margin-top: 18px; color: var(--texto-3); font-size: 0.88rem; }
.telefono { position: relative; justify-self: center; width: min(300px, 78vw); }
.telefono::before { content: ""; position: absolute; inset: -40px; z-index: -1; background: radial-gradient(closest-side, rgba(var(--a-rgb), 0.35), transparent); filter: blur(10px); }
.telefono img { display: block; width: 100%; height: auto; border-radius: 34px; border: 8px solid #141c18; box-shadow: var(--sombra), 0 0 0 1px var(--borde-fuerte); }
.telefono.ladeado { transform: rotate(-3deg); }
@media (max-width: 820px) { .hero { grid-template-columns: 1fr; padding-top: 34px; } .telefono { width: min(260px, 70vw); } }
.ventajas { display: grid; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); gap: 14px; }
.ventajas .card b { display: block; margin: 8px 0 4px; font-size: 1.02rem; }
.ventajas .card span { color: var(--texto-2); font-size: 0.92rem; }
.ventajas .em { font-size: 1.6rem; }
.capturas { display: flex; gap: 16px; overflow-x: auto; padding: 6px 2px 18px; scroll-snap-type: x mandatory; }
.capturas figure { margin: 0; flex: 0 0 210px; scroll-snap-align: start; }
.capturas img { width: 100%; height: auto; border-radius: 22px; border: 6px solid #141c18; box-shadow: 0 0 0 1px var(--borde); }
.capturas figcaption { margin-top: 8px; color: var(--texto-2); font-size: 0.86rem; text-align: center; }

/* ---------- Anuncio de la app ---------- */
.app-cta { display: flex; align-items: center; gap: 18px; margin: 28px 0; padding: 20px 22px; border-radius: var(--radio);
  background: linear-gradient(120deg, rgba(var(--a-rgb), 0.18), rgba(var(--b-rgb), 0.06)); border: 1px solid rgba(var(--a-rgb), 0.35); }
.app-cta img { flex: none; width: 60px; height: 60px; border-radius: 16px; box-shadow: 0 6px 20px rgba(0, 0, 0, 0.35); }
.app-cta div { flex: 1; min-width: 0; }
.app-cta b { display: block; font-size: 1.08rem; }
.app-cta span { color: var(--texto-2); font-size: 0.93rem; }
@media (max-width: 640px) { .app-cta { flex-wrap: wrap; } .app-cta .btn { width: 100%; } }

/* ---------- Temas ---------- */
.crumbs { margin: 26px 0 14px; color: var(--texto-3); font-size: 0.88rem; }
.crumbs a { color: var(--texto-2); text-decoration: none; }
.crumbs a:hover { color: var(--texto); }
.prose { max-width: 760px; color: var(--texto); }
.prose p, .prose li { color: #d3e2da; }
.prose h2 { margin-top: 34px; }
.prose ul, .prose ol { padding-left: 22px; }
.prose li { margin: 4px 0; }
.formulas { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 12px; }
.formulas .card { padding: 16px 18px; }
.formulas .card small { display: block; color: var(--texto-3); font-weight: 700; font-size: 0.74rem; letter-spacing: 0.08em; text-transform: uppercase; margin-bottom: 4px; }
.formulas .katex-display { margin: 6px 0 0; overflow-x: auto; overflow-y: hidden; padding: 4px 0; }

.ej { margin: 0 0 16px; }
.ej-cab { display: flex; align-items: center; gap: 12px; margin-bottom: 4px; }
.ej-num { flex: none; width: 32px; height: 32px; border-radius: 50%; display: grid; place-items: center; background: var(--grad); color: #03140c; font-weight: 800; font-size: 0.9rem; }
.ej-cab h3 { margin: 0; font-size: 1rem; color: var(--texto-2); font-weight: 600; }
.ej-enun { font-size: 1.15rem; overflow-x: auto; overflow-y: hidden; }
.ej-enun .katex-display { margin: 10px 0; }
.ej details { margin-top: 6px; }
.ej summary { list-style: none; cursor: pointer; display: inline-flex; align-items: center; gap: 8px; padding: 9px 15px; border-radius: 12px;
  background: var(--superficie-2); border: 1px solid var(--borde-fuerte); font-weight: 700; font-size: 0.92rem; user-select: none; }
.ej summary::-webkit-details-marker { display: none; }
.ej summary::before { content: "▸"; color: var(--acento-claro); transition: transform 0.15s; }
.ej details[open] summary::before { transform: rotate(90deg); }
.ej summary:hover { border-color: var(--acento); }
.resultado { margin: 16px 0; padding: 14px 18px; border-radius: 16px; border: 1px solid rgba(var(--a-rgb), 0.45); background: rgba(var(--a-rgb), 0.08); overflow-x: auto; }
.resultado .cab { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; font-size: 0.74rem; font-weight: 800; letter-spacing: 0.1em; color: var(--acento-claro); text-transform: uppercase; }
.resultado .katex-display { margin: 8px 0 2px; }
.pasos { list-style: none; margin: 0; padding: 0; counter-reset: paso; }
.pasos li { position: relative; padding: 0 0 16px 44px; counter-increment: paso; }
.pasos li::before { content: counter(paso); position: absolute; left: 0; top: 0; width: 28px; height: 28px; border-radius: 50%; display: grid; place-items: center;
  background: var(--grad); color: #03140c; font-weight: 800; font-size: 0.8rem; }
.pasos li::after { content: ""; position: absolute; left: 13.5px; top: 32px; bottom: 2px; width: 1px; background: var(--borde-fuerte); }
.pasos li:last-child::after { display: none; }
.pasos li.seccion { padding-left: 0; counter-increment: none; color: var(--acento-claro); font-weight: 800; font-size: 0.82rem; letter-spacing: 0.06em; text-transform: uppercase; }
.pasos li.seccion::before, .pasos li.seccion::after { display: none; }
.pasos .t { color: #d3e2da; }
.pasos .f { margin-top: 8px; padding: 6px 14px; border-radius: 14px; background: var(--superficie); border: 1px solid var(--borde); overflow-x: auto; overflow-y: hidden; }
.pasos .f .katex-display { margin: 6px 0; }
.porque { margin-top: 8px; font-size: 0.9rem; color: var(--texto-2); border-left: 3px solid rgba(var(--a-rgb), 0.5); padding: 2px 0 2px 12px; }
.porque b { color: var(--acento-claro); }
.ej .otros { margin-top: 10px; font-size: 0.88rem; color: var(--texto-2); }
.katex { font-size: 1.08em; }

/* ---------- Pie ---------- */
footer.site { margin-top: 60px; border-top: 1px solid var(--borde); background: rgba(0, 0, 0, 0.2); padding: 40px 0 26px; font-size: 0.92rem; }
.foot-cols { display: grid; grid-template-columns: 1.4fr repeat(3, 1fr); gap: 26px; }
.foot-cols h4 { margin: 0 0 10px; font-size: 0.95rem; }
.foot-cols ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 7px; }
.foot-cols a { color: var(--texto-2); text-decoration: none; }
.foot-cols a:hover { color: var(--texto); }
.foot-cols p { color: var(--texto-2); margin: 10px 0 14px; }
.foot-bottom { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 10px; margin-top: 30px; padding-top: 18px; border-top: 1px solid var(--borde); color: var(--texto-3); font-size: 0.85rem; }
.foot-bottom nav { display: flex; flex-wrap: wrap; gap: 14px; }
.foot-bottom a { color: var(--texto-3); text-decoration: none; }
.foot-bottom a:hover { color: var(--texto); }
@media (max-width: 760px) { .foot-cols { grid-template-columns: 1fr 1fr; } .foot-cols > div:first-child { grid-column: 1 / -1; } }

/* ---------- Preguntas frecuentes ---------- */
.faq details { border-bottom: 1px solid var(--borde); padding: 14px 0; }
.faq summary { cursor: pointer; font-weight: 700; }
.faq p { color: var(--texto-2); margin: 10px 0 0; }

/* El texto de los botones verdes siempre en negro (también dentro de los anuncios de la app y del pie) */
a.btn:not(.ghost), a.btn:not(.ghost):hover, .btn:not(.ghost) span, .btn:not(.ghost) small, .btn:not(.ghost) b { color: #03140c !important; }