:root{
  --bg:#0b1220;
  --bg2:#0f1a2f;
  --card:#111c33;
  --text:#eaf0ff;
  --muted:#b8c4e6;
  --line:rgba(234,240,255,.12);
  --accent:#9ed1ff;
  --accent2:#c7b7ff;
  --shadow: 0 10px 30px rgba(0,0,0,.35);
  --radius: 18px;
  --max: 1120px;
}

*{box-sizing:border-box}
html,body{height:100%}

body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Arial;
  background:
    radial-gradient(1200px 700px at 20% 10%, rgba(158,209,255,.18), transparent 60%),
    radial-gradient(1000px 600px at 80% 30%, rgba(199,183,255,.16), transparent 55%),
    linear-gradient(180deg, var(--bg), var(--bg2));
  color: var(--text);
  line-height:1.55;
}

a{color:inherit}

.wrap{
  max-width:var(--max);
  margin:0 auto;
  padding:0 20px;
}

.narrow{max-width:820px}
.muted{color:var(--muted)}

.skip{
  position:absolute;
  left:-999px;
}
.skip:focus{
  left:16px;
  top:16px;
  background:#000;
  padding:10px 12px;
  border-radius:10px;
  z-index:1000;
}

/* ================= HEADER ================= */

.site-header{
  position:sticky;
  top:0;
  z-index:50;
  background: rgba(11,18,32,.72);
  backdrop-filter: blur(10px);
  border-bottom:1px solid var(--line);
}

.header-inner{
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:18px;
  padding:14px 0;
}

.brand{
  display:flex;
  flex-direction:column;
  gap:2px;
}

.brand-mark{
  display:inline-flex;
  align-items:center;
  gap:10px;
  text-decoration:none;
}

.mark{
  width:34px;
  height:34px;
  display:grid;
  place-items:center;
  border-radius:12px;
  background: rgba(158,209,255,.14);
  border:1px solid rgba(158,209,255,.25);
  box-shadow: var(--shadow);
}

.name{
  font-weight:760;
  letter-spacing:.2px;
}

.tagline{
  font-size:13px;
  color:var(--muted);
}

.nav{
  display:flex;
  gap:10px;
  flex-wrap:wrap;
}

.nav-link{
  text-decoration:none;
  padding:8px 10px;
  border-radius:12px;
  color:var(--muted);
  border:1px solid transparent;
}

.nav-link:hover{
  color:var(--text);
  background: rgba(158,209,255,.08);
  border-color: rgba(158,209,255,.25);
}

.nav-link.is-active{
  color:var(--text);
  background: rgba(158,209,255,.10);
  border-color: rgba(158,209,255,.35);
}

/* ================= HERO ================= */

.hero{
  padding:48px 0 28px;
}

.hero-inner{
  display:grid;
  grid-template-columns: 1.2fr .8fr;
  gap:22px;
}

.hero h1{
  font-size: clamp(34px, 4vw, 54px);
  line-height:1.05;
  margin:0 0 12px;
}

.lede{
  font-size:18px;
  color:var(--muted);
}

.hero-actions{
  display:flex;
  gap:12px;
  flex-wrap:wrap;
  margin:18px 0;
}

.btn{
  padding:12px 14px;
  border-radius:14px;
  text-decoration:none;
  font-weight:650;
  border:1px solid rgba(158,209,255,.4);
  background: linear-gradient(180deg, rgba(158,209,255,.20), rgba(158,209,255,.10));
  box-shadow: var(--shadow);
}

.btn-ghost{
  background:transparent;
  border-color: rgba(234,240,255,.18);
}

.hero-notes{
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:12px;
  margin-top:18px;
}

.note{
  border:1px solid var(--line);
  border-radius:var(--radius);
  padding:12px;
  background: rgba(17,28,51,.55);
}

.note-title{font-weight:720}
.note-body{color:var(--muted); font-size:14px}

/* ================= SECTIONS ================= */

.section{
  padding:36px 0;
}

.section-alt{
  background: rgba(255,255,255,.03);
  border-top:1px solid var(--line);
  border-bottom:1px solid var(--line);
}

.section-head{
  display:flex;
  justify-content:space-between;
  align-items:flex-end;
  gap:14px;
  flex-wrap:wrap;
}

.grid3{
  margin-top:18px;
  display:grid;
  grid-template-columns: repeat(3, 1fr);
  gap:14px;
}

.grid2{
  margin-top:18px;
  display:grid;
  grid-template-columns: repeat(2, 1fr);
  gap:14px;
}

.tile{
  border:1px solid var(--line);
  border-radius:var(--radius);
  padding:16px;
  background: rgba(17,28,51,.45);
}

/* ================= BOOK LIST ================= */

.books{
  margin-top:18px;
  display:grid;
  gap:14px;
}

.book{
  display:grid;
  grid-template-columns: 80px 1fr;
  gap:14px;
  align-items:center;
  border:1px solid var(--line);
  border-radius:var(--radius);
  padding:14px;
  background: rgba(17,28,51,.45);
}

/* 🔹 BOOK COVER USING background-image (SCALED TO FIT) */

.book-cover{
  width:70px;
  height:70px;
  border-radius:12px;
  border:1px solid rgba(158,209,255,.25);
  background-color: rgba(17,28,51,.35);

  background-size: contain;
  background-position: center;
  background-repeat: no-repeat;

  box-shadow:
    inset 0 0 0 1px rgba(255,255,255,.05),
    0 6px 18px rgba(0,0,0,.35);
}

.book-title{
  font-weight:800;
}

.book-author{
  color:var(--muted);
  font-size:14px;
}

.book-desc{
  color:var(--muted);
  margin-top:6px;
}

/* ================= CTA ================= */

.cta{
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:16px;
  flex-wrap:wrap;
  border:1px solid rgba(158,209,255,.20);
  border-radius:var(--radius);
  padding:16px;
  background: rgba(158,209,255,.08);
}

.cta-actions{
  display:flex;
  gap:10px;
  flex-wrap:wrap;
}

/* ================= PAGE ================= */

.page{
  padding:40px 0;
}

.page h1{
  font-size:38px;
  margin-bottom:12px;
}

.bullets li{
  margin:8px 0;
  color:var(--muted);
}

/* ================= FOOTER ================= */

.site-footer{
  border-top:1px solid var(--line);
  padding:18px 0;
  color:var(--muted);
}

.footer-inner{
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:12px;
  flex-wrap:wrap;
}

.footer-links{
  display:flex;
  gap:14px;
}

.footer-links a{
  text-decoration:none;
  color:var(--muted);
}

.footer-links a:hover{
  color:var(--text);
  text-decoration:underline;
}

/* ================= RESPONSIVE ================= */

@media (max-width:900px){
  .hero-inner{
    grid-template-columns:1fr;
  }
}

@media (max-width:760px){
  .grid3,
  .grid2{
    grid-template-columns:1fr;
  }
  .hero-notes{
    grid-template-columns:1fr;
  }
}