/* Arquitectura al Día — estilos compartidos de las lecciones (limpio y profesional) */
:root{
  --bg:#ffffff;
  --bg-alt:#f4f7fa;
  --ink:#1b2733;
  --ink-soft:#4d5a68;
  --ink-faint:#7b8794;
  --navy:#13294b;
  --blue:#1d63c7;
  --blue-d:#16519f;
  --blue-tint:#eaf2fd;
  --green:#157a4d;
  --green-tint:#e7f4ee;
  --red:#c0392b;
  --red-tint:#fbeae8;
  --border:#dce3ec;
  --shadow:0 1px 2px rgba(16,42,77,.05), 0 8px 24px -16px rgba(16,42,77,.25);
  --font:"Public Sans",-apple-system,BlinkMacSystemFont,"Segoe UI",system-ui,sans-serif;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;scroll-padding-top:80px;font-size:112.5%}
body{font-family:var(--font);color:var(--ink);background:var(--bg);line-height:1.65;font-size:1.1rem;-webkit-font-smoothing:antialiased}
::selection{background:var(--blue);color:#fff}
a{color:var(--blue)}
strong{font-weight:700;color:var(--ink)}

header.bar{position:sticky;top:0;z-index:50;display:flex;align-items:center;justify-content:space-between;gap:1rem;
  padding:.85rem clamp(1rem,4vw,2.5rem);background:rgba(255,255,255,.93);backdrop-filter:blur(8px);border-bottom:1px solid var(--border)}
.bar a{font-weight:600;font-size:.95rem;color:var(--blue);text-decoration:none;display:inline-flex;align-items:center;gap:.35rem}
.bar a:hover{text-decoration:underline}
.bar .pos{font-size:.9rem;color:var(--ink-faint);font-weight:500;white-space:nowrap}
@media(max-width:520px){.bar .pos{display:none}}

main{max-width:720px;margin:0 auto;padding:clamp(2rem,5vw,3.5rem) clamp(1.1rem,4vw,2rem) 4rem}

.crumb{font-size:.92rem;font-weight:700;color:var(--blue)}
.crumb .nuevo{color:var(--green)}
h1{font-size:clamp(1.8rem,4.5vw,2.5rem);font-weight:800;color:var(--navy);line-height:1.18;letter-spacing:-.01em;margin:.6rem 0 .5rem}
.read-time{font-size:.92rem;color:var(--ink-faint)}
.lead{font-size:1.2rem;color:var(--ink-soft);margin-top:.4rem}

h2{font-size:clamp(1.3rem,3vw,1.6rem);font-weight:700;color:var(--navy);margin:2.4rem 0 .9rem;line-height:1.25;display:flex;align-items:center;gap:.65rem}
h2 .num{display:inline-flex;align-items:center;justify-content:center;min-width:1.7rem;height:1.7rem;background:var(--blue);color:#fff;border-radius:50%;font-size:.9rem;font-weight:700;flex:0 0 auto}
p{margin:0 0 1.05rem}
.muted{color:var(--ink-soft)}

ul.list{list-style:none;display:grid;gap:.55rem;margin:0 0 1.2rem}
ul.list li{padding-left:1.7rem;position:relative}
ul.list li::before{content:"";position:absolute;left:.15rem;top:.6em;width:.5rem;height:.5rem;background:var(--blue);border-radius:50%}

ol.steps{counter-reset:s;list-style:none;display:grid;gap:.7rem;margin:0 0 1.2rem}
ol.steps li{padding-left:2.7rem;position:relative;padding-top:.15rem}
ol.steps li::before{counter-increment:s;content:counter(s);position:absolute;left:0;top:0;width:1.85rem;height:1.85rem;
  background:var(--blue-tint);color:var(--blue-d);border:1px solid var(--blue);border-radius:50%;display:flex;align-items:center;justify-content:center;font-weight:700;font-size:.95rem}

/* antes / ahora */
.ba{display:grid;grid-template-columns:1fr 1fr;gap:1rem;margin:1.4rem 0}
@media(max-width:560px){.ba{grid-template-columns:1fr}}
.ba div{border:1px solid var(--border);border-radius:10px;padding:1.2rem 1.3rem}
.ba .antes{background:var(--bg-alt)}
.ba .ahora{background:var(--blue-tint);border-color:#cfe0f7}
.ba h4{font-size:.8rem;font-weight:700;text-transform:uppercase;letter-spacing:.06em;margin-bottom:.5rem}
.ba .antes h4{color:var(--ink-faint)} .ba .ahora h4{color:var(--blue-d)}
.ba p{font-size:1.02rem;margin:0;color:var(--ink-soft)}

/* palabras nuevas */
.words{border:1px solid var(--border);border-radius:10px;background:var(--bg-alt);padding:1.4rem 1.5rem;margin:1.4rem 0}
.words dl{margin:0}
.words dt{font-weight:700;font-size:1.05rem;color:var(--navy);margin-top:1.1rem}
.words dt:first-child{margin-top:0}
.words dd{margin:.2rem 0 0;color:var(--ink-soft);font-size:1.02rem;line-height:1.55}

/* callouts */
.box{background:var(--blue-tint);border:1px solid #cfe0f7;border-left:4px solid var(--blue);border-radius:0 10px 10px 0;padding:1.2rem 1.4rem;margin:1.4rem 0}
.box .k{font-size:.78rem;font-weight:700;text-transform:uppercase;letter-spacing:.06em;color:var(--blue-d);display:block;margin-bottom:.4rem}
.box p:last-child{margin-bottom:0}
.box.key{background:var(--green-tint);border-color:#cce8d8;border-left-color:var(--green)}
.box.key .k{color:var(--green)}

/* video (poster -> click to play) */
.video{margin:1.4rem 0;border:1px solid var(--border);border-radius:12px;overflow:hidden;background:var(--bg);box-shadow:var(--shadow)}
.video__frame{position:relative;width:100%;aspect-ratio:16/9;background:#0f1f33}
.video__frame iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.ytlite{position:absolute;inset:0;display:block;cursor:pointer;overflow:hidden}
.ytlite img{width:100%;height:100%;object-fit:cover;display:block}
.ytlite::after{content:"";position:absolute;inset:0;background:linear-gradient(180deg,rgba(0,0,0,.05),rgba(0,0,0,.3))}
.ytlite .play{position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);z-index:2;width:78px;height:54px;border-radius:14px;background:#e23b2e;display:flex;align-items:center;justify-content:center;box-shadow:0 6px 18px rgba(0,0,0,.4);transition:.16s}
.ytlite:hover .play{transform:translate(-50%,-50%) scale(1.06)}
.ytlite .play::before{content:"";border-style:solid;border-width:11px 0 11px 19px;border-color:transparent transparent transparent #fff;margin-left:4px}
.video figcaption{padding:1.1rem 1.3rem 1.2rem}
.video figcaption .tag{display:block;font-size:.8rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--blue-d);margin-bottom:.5rem}
.video figcaption .t{display:block;font-weight:700;font-size:1.08rem;color:var(--navy);margin-bottom:.4rem;line-height:1.3}
.video figcaption .d{display:block;font-size:1rem;color:var(--ink-soft);line-height:1.5}
.video figcaption a{font-weight:600;text-decoration:none}
.video figcaption a:hover{text-decoration:underline}

/* resources */
.res{display:grid;gap:.8rem;margin:1.4rem 0}
.res a,.res span.item{display:block;border:1px solid var(--border);border-radius:10px;padding:1.1rem 1.3rem;background:var(--bg);text-decoration:none;color:inherit;transition:.14s}
.res a:hover{border-color:var(--blue);box-shadow:var(--shadow)}
.res .tag{display:block;font-size:.78rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--blue-d);margin-bottom:.5rem}
.res .t{display:block;font-weight:700;font-size:1.08rem;color:var(--navy);margin-bottom:.35rem;line-height:1.3}
.res .d{display:block;font-size:1rem;color:var(--ink-soft);line-height:1.5}

/* quiz */
.quiz{margin-top:1rem}
.q{border:1px solid var(--border);border-radius:12px;background:var(--bg);padding:1.4rem 1.5rem;margin-bottom:1.1rem;box-shadow:var(--shadow)}
.q .qq{font-weight:700;font-size:1.1rem;color:var(--navy);margin-bottom:.9rem;line-height:1.3}
.opt{display:block;width:100%;text-align:left;font-family:inherit;font-size:1.05rem;color:var(--ink);background:var(--bg);border:2px solid var(--border);border-radius:9px;padding:.85rem 1.05rem;margin-bottom:.6rem;cursor:pointer;transition:.14s;line-height:1.4}
.opt:hover{border-color:var(--blue);background:var(--blue-tint)}
.opt.ok{border-color:var(--green);background:var(--green-tint)}
.opt.no{border-color:var(--red);background:var(--red-tint)}
.fb{margin-top:.5rem;font-size:1rem;font-weight:600;padding:.4rem .1rem}
.fb.good{color:var(--green)} .fb.bad{color:var(--red)}

/* prev / next */
.nav{display:grid;grid-template-columns:1fr 1fr;gap:1rem;margin-top:3rem;border-top:1px solid var(--border);padding-top:1.8rem}
.nav .navcard{display:flex;flex-direction:column;justify-content:center;gap:.3rem;border:1px solid var(--border);border-radius:10px;padding:1rem 1.2rem;background:var(--bg);text-decoration:none;color:inherit;transition:.14s}
.nav a.navcard:hover{border-color:var(--blue);background:var(--blue-tint)}
.nav .navcard .dir{font-size:.8rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--blue-d)}
.nav .navcard .ttl{font-weight:700;font-size:1.05rem;color:var(--navy);line-height:1.25}
.nav .navcard.next{text-align:right;align-items:flex-end}
.nav .navcard.soon{opacity:.7;cursor:default}
.nav .navcard.soon:hover{border-color:var(--border);background:var(--bg)}
.nav .navcard .soon-tag{align-self:flex-end;margin-top:.15rem;font-size:.7rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--ink-faint);border:1px solid var(--border);border-radius:4px;padding:.12rem .5rem}
@media(max-width:560px){.nav{grid-template-columns:1fr}.nav .navcard.next{text-align:left;align-items:flex-start}.nav .navcard .soon-tag{align-self:flex-start}}

footer{padding:2.5rem clamp(1rem,4vw,2.5rem);text-align:center;background:var(--navy);color:#9fb0c6;margin-top:2.5rem}
footer .b{font-weight:800;font-size:1.2rem;color:#fff}
footer .m{font-size:.9rem;margin-top:.4rem}

@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}