/* NTEbooks - Phase 0 web styles
   Shared by index.html, for-lecturers.html, flyer.html
   Design tokens mirror ETBOOK-Spec-v2.md 12.2 */

:root{
  --brand:#0B6B4F; --brand-dim:#0A5A42; --brand-tint:#EAF3EF;
  --deep:#064439; --mint:#E2F4EB; --glow:#BCFCC1;
  --logo-ink:#064439; --logo-glow:#BCFCC1;
  --accent:#F2A100;
  --base:#FFFFFF; --card:#FFFFFF; --ink:#101613; --muted:#5C6B63; --line:#E3E8E4;
  --ok:#1E8E5A; --warn:#B26A00; --danger:#C0392B;
  --r-card:14px; --r-pill:999px;
  --shadow:0 1px 2px rgba(6,68,57,.08), 0 10px 26px rgba(6,68,57,.09);
  --maxw:640px;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body{margin:0;background:var(--base);color:var(--ink);padding-bottom:84px;
  font:16px/1.55 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif}
img{max-width:100%;display:block}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}

.wrap{max-width:var(--maxw);margin:0 auto;padding:0 16px}
section{padding:30px 0}
section + section{border-top:1px solid var(--line)}
.hero + section{border-top:0}
.eyebrow{font-size:12px;font-weight:800;letter-spacing:.09em;text-transform:uppercase;
  color:var(--brand);margin:0 0 8px}
h1{font-size:28px;line-height:1.18;margin:0 0 10px;letter-spacing:-.02em}
h2{font-size:21px;line-height:1.3;margin:0 0 14px;letter-spacing:-.01em}
h3{font-size:16px;margin:0 0 6px}
p{margin:0 0 12px}
.lede{font-size:17px;color:var(--muted);margin:0 0 18px}
.muted{color:var(--muted);font-size:14px}
.tiny{color:var(--muted);font-size:12px;line-height:1.5}

.hero{position:relative;overflow:hidden;color:#fff;
  background:linear-gradient(180deg,var(--brand) 0%,var(--deep) 100%);
  padding:32px 0 36px;margin-bottom:4px}
.hero::after{content:"";position:absolute;right:-80px;top:-70px;width:300px;height:300px;
  border-radius:50%;
  background:radial-gradient(circle,rgba(188,252,193,.30),rgba(188,252,193,0) 70%)}
.hero .wrap{position:relative}
.hero-mark{width:64px;height:auto;margin:0 0 14px; filter:drop-shadow(0 6px 16px rgba(0,0,0,.28))}
.hero .eyebrow{color:var(--glow)}
.hero h1{color:#fff;font-size:30px}
.hero .lede{color:var(--mint)}
.hero .role-card:hover{transform:translateY(-3px);box-shadow:0 14px 34px rgba(6,68,57,.22)}

.top{background:var(--base);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:20}
.top .wrap{display:flex;align-items:center;gap:12px;height:56px;max-width:820px}
.logo{display:flex;align-items:center;gap:8px;font-weight:800;letter-spacing:-.02em;
  color:var(--logo-ink)}
/* The mark is the book-and-brain cut-out: PNG with a real alpha channel, so it
   sits on the white header with no plate behind it. Rebuild with
   py tools/make-logo-assets.py  if the artwork ever changes. The light-ink
   variant for dark surfaces is built by tools/make-covers.py. */
.logo .mark{width:30px;height:auto;flex:0 0 auto}
.top nav{margin-left:auto;display:flex;gap:16px;font-size:14px;font-weight:600}
/* Social row in the homepage header - fills the space the nav used to take there.
   Single-path SVGs in --logo-ink, same convention as assets/icon-student.svg.
   .top .social scores 0,2,0 and so overrides .top nav{...} (0,1,1) on gap. */
.top .social{margin-left:auto;display:flex;align-items:center;gap:2px}
.top .social a{display:grid;place-items:center;width:32px;height:32px;
  border-radius:50%;transition:background .15s}
.top .social a:hover{background:var(--brand-tint);text-decoration:none}
.top .social img{width:17px;height:17px;display:block}
@media (max-width:380px){
  .top .social{gap:0}
  .top .social a{width:29px;height:29px}
  .top .social img{width:16px;height:16px}
}

.role-card{ display:flex;flex-direction:column;align-items:center;justify-content:center;gap:14px;
  text-decoration:none;text-align:center;
  background:var(--card);border:1px solid var(--line);
  border-radius:var(--r-card);box-shadow:var(--shadow);
  padding:24px 20px;cursor:pointer;
  transition:box-shadow .18s,transform .15s;
  width:100%;max-width:300px;margin-inline:auto}
.role-card:hover{transform:translateY(-3px);
  box-shadow:0 14px 34px rgba(6,68,57,.22)}
.role-card .role-icon{width:56px;height:56px;border-radius:50%;
  background:linear-gradient(135deg,var(--brand),var(--deep));
  display:grid;place-items:center;margin:0 auto}
.role-card .role-icon img{width:28px;height:auto;filter:invert(1)}
.role-card h3{margin:0;font-size:17px;font-weight:700;color:var(--deep); text-align:center}
.role-card p{margin:0;font-size:14px;color:var(--muted); text-align:center;line-height:1.5}
.role-card .btn{width:100%;max-width:200px;margin-inline:auto}

/* No hover underline on interface elements. The global a:hover rule scores
   0,1,1 and would beat .role-card (0,1,0), underlining the whole card - its
   heading, its copy and its button label. Running-text links keep theirs. */
.logo:hover,.logo:hover *,
.role-card:hover,.role-card:hover *,
.top nav a:hover,.top nav a:hover *,
.btn:hover,.btn:hover *{text-decoration:none}

.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;
  text-align:center;min-height:44px;padding:10px 20px;border-radius:var(--r-pill);
  border:1px solid transparent;font:inherit;font-weight:700;cursor:pointer;
  width:100%;transition:background .15s,box-shadow .15s,border-color .15s,transform .10s}
.btn:hover{text-decoration:none;transform:translateY(-1px)}
.btn:active{transform:translateY(0)}
.btn-primary{background:var(--accent);color:#1a1000;
  box-shadow:0 4px 14px rgba(242,161,0,.30)}
.btn-primary:hover{background:#e18e00;
  box-shadow:0 6px 18px rgba(242,161,0,.35)}
.btn-ghost{background:var(--brand-tint);color:var(--deep); border-color:var(--line)}
.btn-ghost:hover{background:var(--brand);color:#fff;
  border-color:var(--brand);box-shadow:0 6px 18px rgba(11,107,79,.25)}
.btn-secondary{background:#fff;color:var(--deep); border-color:var(--line)}
.btn-secondary:hover{background:var(--brand);color:#fff;
  border-color:var(--brand);box-shadow:0 6px 18px rgba(11,107,79,.25)}
.btn-sm{font-size:14px;padding:8px 18px;min-height:40px}
.btn-block{display:block;width:100%;margin-top:16px}
.btn-buy{width:auto;flex:0 0 auto;padding:10px 18px}
.btn-row{display:flex;gap:10px;flex-wrap:wrap}
.btn-row .btn{width:auto;flex:1 1 150px;min-width:130px}

.card{background:var(--card);border:1px solid var(--line);
  border-radius:var(--r-card);padding:18px;box-shadow:var(--shadow);
  margin-top:14px;position:relative;overflow:hidden}
.card + .card{margin-top:14px}
.card:hover{transform:translateY(-1px);
  box-shadow:0 6px 20px rgba(6,68,57,.12)}
.card-hot{border:2px solid var(--brand);
  box-shadow:0 14px 34px rgba(11,107,79,.18)}
.card-hot::before{content:"";position:absolute;top:0;left:0;right:0;height:4px;
  background:linear-gradient(90deg,var(--brand),var(--deep))}
.ribbon{position:absolute;top:-11px;right:14px;
  background:var(--accent);color:#1a1000;
  font-size:11px;font-weight:800;letter-spacing:.07em;
  text-transform:uppercase;padding:5px 12px;border-radius:var(--r-pill);
  box-shadow:0 3px 10px rgba(242,161,0,.30)}
.card-head{display:flex;gap:14px;align-items:flex-start}
.cover{width:96px;height:auto;border-radius:10px;flex:0 0 auto;
  box-shadow:0 6px 16px rgba(6,68,57,.20)}
.card-body{min-width:0;flex:1}
.code{font-weight:800;letter-spacing:.01em;color:var(--deep)}
.facts{display:flex;gap:10px;flex-wrap:wrap;margin:8px 0 0;padding:0;list-style:none}
.facts li{font-size:13px;color:var(--muted)}
.facts li + li::before{content:"\00B7";margin-right:8px;color:var(--line)}
.topics{margin:10px 0 0;padding-left:18px;font-size:14px;color:var(--muted)}
.topics li{margin:2px 0}
.card-badge{display:inline-block;font-size:11px;font-weight:800;
  text-transform:uppercase;letter-spacing:.07em;padding:5px 10px;
  border-radius:var(--r-pill);background:rgba(255,255,255,.2);
  color:#fff;backdrop-filter:blur(4px)}
.badge-free{background:var(--brand-tint);border-color:var(--brand-tint);
  color:var(--brand)}
.badge-popular{background:var(--accent);color:#1a1000}
.badge-new{background:var(--brand);color:#fff}

.price-row{display:flex;align-items:center;gap:10px;
  margin:14px 0 12px;padding-top:12px;border-top:1px solid var(--line)}
.price{font-variant-numeric:tabular-nums;font-size:20px;font-weight:800;
  color:var(--deep);letter-spacing:-.01em}
.price-was{font-variant-numeric:tabular-nums;font-size:14px;color:var(--muted);
  text-decoration:line-through}

.trust{display:flex;gap:8px;flex-wrap:wrap;margin:0;padding:0;list-style:none}
.trust li{font-size:13px;background:var(--card);border:1px solid var(--line);
  border-radius:var(--r-pill);padding:6px 12px;color:var(--muted)}
.hero .trust li{background:rgba(226,244,235,.14);
  border-color:rgba(226,244,235,.4);color:#fff}

.demo{display:flex;gap:22px;align-items:flex-start;flex-wrap:wrap}
.phone{flex:0 0 auto;width:232px;border-radius:28px;background:var(--deep);
  padding:10px;box-shadow:0 20px 44px rgba(6,68,57,.35);
  transform:rotate(-2deg);margin:6px 0 10px}
.phone-screen{background:#fff;border-radius:20px;overflow:hidden;
  padding:14px 14px 12px}
.pg-head{display:flex;justify-content:space-between;gap:8px;
  font-size:11px;font-weight:600;color:var(--muted);
  border-bottom:1px solid var(--line);padding-bottom:8px;margin-bottom:10px}
.phone-screen h4{margin:0 0 6px;font-size:15px}
.phone-screen p{font-size:12.5px;line-height:1.55;margin:0 0 8px}
.pg-box{background:var(--brand-tint);border:1px solid var(--brand);
  border-radius:8px;padding:8px 10px;margin:2px 0}

.benefits{display:grid;gap:14px}
.benefits .card{background:var(--brand-tint);
  border-color:var(--line);text-align:center}
.benefits .card h3{color:var(--deep);font-weight:600}
.benefit-num{width:42px;height:42px;border-radius:50%;
  background:var(--brand);color:#fff;display:grid;place-items:center;
  font-weight:800;margin:0 auto 12px}

.earn{display:flex;gap:16px;align-items:center;
  margin-top:14px;padding:18px;border-radius:var(--r-card);
  color:#fff;background:linear-gradient(135deg,var(--brand),var(--deep));
  box-shadow:0 14px 30px rgba(6,68,57,.30)}
.earn-num{flex:0 0 auto;font-size:46px;font-weight:800;line-height:1;
  letter-spacing:-.03em;color:var(--glow);font-variant-numeric:tabular-nums}
.earn h3{color:#fff;margin:0 0 4px;font-size:17px}
.earn p{margin:0;font-size:14px;color:var(--mint)}

.promise{background:var(--brand-tint);border:1px solid var(--brand);
  border-radius:var(--r-card);padding:16px;margin:0 0 14px}
.promise h3{color:var(--brand)}

details{background:var(--card);border:1px solid var(--line);
  border-radius:var(--r-card);padding:14px 16px;margin-bottom:10px}
details summary{font-weight:600;cursor:pointer;list-style:none}
details summary::-webkit-details-marker{display:none}
details summary::after{content:"+";float:right;color:var(--brand);font-weight:700}
details[open] summary::after{content:"\2013"}
details p{margin:10px 0 0;font-size:15px;color:var(--muted)}

label{display:block;font-size:14px;font-weight:600;margin:0 0 6px}
input,select,textarea{width:100%;font:inherit;color:var(--ink);background:var(--card);
  border:1px solid var(--line);border-radius:10px;padding:12px 14px;margin-bottom:14px}
input:focus,select:focus,textarea:focus{outline:2px solid var(--brand);outline-offset:1px}

.sticky-cta{position:fixed;left:0;right:0;bottom:0;z-index:30;color:#fff;
  background:linear-gradient(180deg,var(--brand),var(--deep));
  padding:10px 16px calc(10px + env(safe-area-inset-bottom));
  box-shadow:0 -8px 24px rgba(6,68,57,.25)}
.sticky-cta .wrap{padding:0;display:flex;align-items:center;gap:12px; justify-content:center}
.sticky-cta .price{font-size:20px;color:#fff}
.sticky-cta .btn{width:auto;flex:0 0 auto;background:#fff;
  color:var(--deep);box-shadow:none;font-weight:600}
.sticky-cta .btn:hover{background:var(--mint)}

[hidden]{display:none !important}
.fallback{margin-top:14px;padding:14px;border:1px solid var(--brand);
  border-radius:var(--r-card);background:var(--brand-tint)}
.fallback p{margin:0 0 10px;font-size:14px}
.fallback .row{display:flex;gap:10px;flex-wrap:wrap;margin-bottom:10px}
.fallback .row .btn{width:auto}
.fallback textarea{margin-bottom:0;font-size:13px}

footer{padding:24px 0 30px;color:var(--muted);font-size:13px;
  border-top:1px solid var(--line)}
footer a{color:var(--muted);text-decoration:underline}
.foot-links{display:flex;gap:14px;flex-wrap:wrap;margin-bottom:10px}

.foot-dark{margin-top:34px;padding:26px 0 30px;color:var(--mint);
  background:linear-gradient(180deg,var(--brand),var(--deep))}
.foot-dark .wrap{display:flex;gap:14px;align-items:flex-start}
.foot-dark img{margin-top:2px;flex:0 0 auto}
.foot-dark .foot-links{margin-bottom:8px}
.foot-dark .foot-links a{color:#fff;text-decoration:none;font-weight:600}
.foot-dark .foot-links a:hover{text-decoration:underline}
.foot-dark .tiny{color:rgba(226,244,235,.78)}

@media (min-width:720px){
  body{padding-bottom:0}
  .sticky-cta{display:none}
  .wrap,.top .wrap{max-width:820px}
  .hero h1{font-size:38px}
  h1{font-size:36px}
  .benefits{grid-template-columns:1fr 1fr}
  .cards-wide{display:grid;grid-template-columns:1fr 1fr;gap:14px}
  .cards-wide .card + .card{margin-top:0}
  .card-hot{grid-column:1 / -1}
  .btn-block{max-width:280px}
}

@media print{
  .top,.sticky-cta,footer,.foot-dark,.hero{display:none}
  body{background:#fff;padding:0}
}

/* ---- Sample author profile (author-sample.html only) --------------------
   Namespaced to classes no other page uses, so it is safe in the shared
   stylesheet. Kept here rather than a second file so the page cannot drift
   from the token set above. */
.sample-band{background:var(--accent);color:#1a1000;font-size:13px;font-weight:700;
  line-height:1.45;text-align:center;padding:10px 16px}
.sample-band strong{text-transform:uppercase;letter-spacing:.07em}

.profile{display:flex;align-items:center;gap:14px;margin:0 0 12px}
.profile h2{margin:0}
.avatar{width:64px;height:64px;border-radius:50%;flex:0 0 auto;
  display:grid;place-items:center;font-size:22px;font-weight:800;letter-spacing:.02em;
  color:#fff;background:linear-gradient(135deg,var(--brand),var(--deep));
  box-shadow:0 8px 20px rgba(6,68,57,.26)}
.profile .who{font-size:14px;color:var(--muted);margin:0}
.verified{display:inline-block;font-size:11px;font-weight:800;text-transform:uppercase;
  letter-spacing:.07em;padding:5px 12px;border-radius:var(--r-pill);margin:0 0 10px;
  background:var(--brand-tint);color:var(--brand);border:1px solid var(--line)}

.stats{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:14px 0 0}
.stat{background:var(--card);border:1px solid var(--line);border-radius:var(--r-card);
  padding:14px;box-shadow:var(--shadow)}
.stat b{display:block;font-size:24px;font-weight:800;line-height:1.1;color:var(--deep);
  letter-spacing:-.02em;font-variant-numeric:tabular-nums}
.stat span{display:block;font-size:12.5px;color:var(--muted);margin-top:4px}

@media (min-width:720px){
  .stats{grid-template-columns:repeat(4,1fr)}
}