:root{
    --chalkboard: #1F3B32;
    --chalkboard-2: #16302A;
    --chalk: #F3EEE1;
    --paper: #FBF7EE;
    --paper-line: #D9D0B8;
    --chalk-yellow: #E4BE68;
    --ink: #1A2320;
    --chalk-blue: #8FB4C0;
    --serif: 'Fraunces', serif;
    --sans: 'Source Sans 3', sans-serif;
    --mono: 'Space Mono', monospace;
  }
  *{box-sizing:border-box; margin:0; padding:0;}
  html{scroll-behavior:smooth;}
  @media (prefers-reduced-motion: reduce){
    html{scroll-behavior:auto;}
    *{animation-duration:0.01ms !important; animation-iteration-count:1 !important; transition-duration:0.01ms !important;}
  }
  body{
    font-family:var(--sans);
    color:var(--ink);
    background:var(--paper);
    line-height:1.6;
    -webkit-font-smoothing:antialiased;
  }
  a{color:inherit;}
  img,svg{display:block; max-width:100%;}

  :focus-visible{
    outline:3px solid var(--chalk-yellow);
    outline-offset:3px;
  }

  .container{
    max-width:1080px;
    margin:0 auto;
    padding:0 28px;
  }

  /* ---------- NAV ---------- */
  header.site-nav{
    position:fixed; top:0; left:0; right:0; z-index:100;
    background:rgba(22,48,42,0.96);
    backdrop-filter:blur(6px);
    border-bottom:1px solid rgba(228,190,104,0.25);
  }
  .nav-inner{
    display:flex; align-items:center; justify-content:space-between;
    padding:16px 28px;
    max-width:1080px; margin:0 auto;
  }
  .brand{
    display:flex; align-items:baseline; gap:10px;
    color:var(--chalk);
    text-decoration:none;
  }
  .brand-mark{
    font-family:var(--serif); font-style:italic; font-weight:500;
    font-size:1.35rem; letter-spacing:0.02em;
  }
  .brand-sub{
    font-family:var(--mono); font-size:0.62rem; letter-spacing:0.18em;
    text-transform:uppercase; color:var(--chalk-yellow);
  }
  nav.main-links{
    display:flex; gap:32px; list-style:none;
  }
  nav.main-links a{
    font-family:var(--sans); font-size:0.92rem; font-weight:600;
    color:var(--chalk); text-decoration:none;
    position:relative; padding-bottom:4px;
    opacity:0.88;
  }
  nav.main-links a::after{
    content:""; position:absolute; left:0; bottom:0;
    width:0; height:1.5px; background:var(--chalk-yellow);
    transition:width 0.25s ease;
  }
  nav.main-links a:hover{opacity:1;}
  nav.main-links a:hover::after{width:100%;}

  .nav-toggle{
    display:none; background:none; border:none; cursor:pointer;
    width:32px; height:24px; position:relative;
  }
  .nav-toggle span, .nav-toggle span::before, .nav-toggle span::after{
    content:""; position:absolute; left:0; width:100%; height:2px;
    background:var(--chalk); transition:transform 0.25s ease, opacity 0.25s ease;
  }
  .nav-toggle span{top:11px;}
  .nav-toggle span::before{top:-9px;}
  .nav-toggle span::after{top:9px;}
  .nav-toggle.open span{background:transparent;}
  .nav-toggle.open span::before{transform:translateY(9px) rotate(45deg);}
  .nav-toggle.open span::after{transform:translateY(-9px) rotate(-45deg);}

  @media (max-width:760px){
    nav.main-links{
      position:absolute; top:100%; left:0; right:0;
      flex-direction:column; gap:0;
      background:var(--chalkboard-2);
      max-height:0; overflow:hidden;
      transition:max-height 0.3s ease;
    }
    nav.main-links.open{max-height:320px;}
    nav.main-links a{
      padding:16px 28px; width:100%; border-top:1px solid rgba(228,190,104,0.12);
    }
    .nav-toggle{display:block;}
  }

  /* ---------- CHALK TEXTURE HELPERS ---------- */
  .chalkboard-bg{
    background-color:var(--chalkboard);
    background-image:
      radial-gradient(rgba(255,255,255,0.025) 1px, transparent 1px);
    background-size:5px 5px;
    color:var(--chalk);
  }
  .paper-bg{
    background-color:var(--paper);
    background-image:
      linear-gradient(var(--paper-line) 1px, transparent 1px),
      linear-gradient(90deg, var(--paper-line) 1px, transparent 1px);
    background-size:34px 34px;
    background-position:-1px -1px;
    position:relative;
  }
  .paper-bg::before{
    content:""; position:absolute; inset:0;
    background:radial-gradient(ellipse at top, rgba(251,247,238,0) 0%, var(--paper) 78%);
    pointer-events:none;
  }

  section{padding:110px 0; position:relative;}
  @media (max-width:760px){ section{padding:78px 0;} }

  .eyebrow{
    font-family:var(--mono); font-size:0.72rem; letter-spacing:0.2em;
    text-transform:uppercase; color:var(--chalk-yellow);
    display:flex; align-items:center; gap:10px; margin-bottom:22px;
  }
  .paper-bg .eyebrow{color:#8a7a3f;}
  .eyebrow .rule{height:1px; width:38px; background:currentColor; opacity:0.55;}

  h1,h2,h3{font-family:var(--serif); font-weight:600; line-height:1.12;}

  /* ---------- HERO ---------- */
  .hero{
    padding-top:170px;
    overflow:hidden;
  }
  .hero-grid{
    display:grid; grid-template-columns:1.1fr 0.9fr;
    gap:50px; align-items:center;
  }
  @media (max-width:860px){
    .hero-grid{grid-template-columns:1fr;}
    .hero-figure{order:-1; max-width:280px; margin:0 auto 20px;}
  }
  .hero h1{
    font-size:clamp(2.4rem, 5vw, 3.6rem);
    color:var(--chalk);
    margin-bottom:20px;
  }
  .hero h1 em{
    font-style:italic; color:var(--chalk-yellow);
  }
  .hero p.lede{
    font-size:1.12rem; max-width:46ch; color:rgba(243,238,225,0.86);
    margin-bottom:32px;
  }
  .hero blockquote{
    font-family:var(--serif); font-style:italic; font-size:1.05rem;
    color:var(--chalk-blue); border-left:2px solid var(--chalk-yellow);
    padding-left:18px; max-width:44ch; margin-bottom:38px;
  }
  .cta-row{display:flex; gap:16px; flex-wrap:wrap;}
  .btn{
    display:inline-flex; align-items:center; gap:10px;
    font-family:var(--sans); font-weight:700; font-size:0.98rem;
    padding:15px 28px; border-radius:3px;
    text-decoration:none; border:1.5px solid transparent;
    cursor:pointer; transition:transform 0.18s ease, background 0.18s ease, color 0.18s ease;
  }
  .btn-primary{
    background:var(--chalk-yellow); color:#221a06;
  }
  .btn-primary:hover{transform:translateY(-2px);}
  .btn-ghost{
    border-color:rgba(243,238,225,0.4); color:var(--chalk);
  }
  .btn-ghost:hover{border-color:var(--chalk); transform:translateY(-2px);}

  .hero-figure{
    width:100%; max-width:400px; margin-left:auto;
  }

  /* ---------- CHALK INTEGRAL SIGNATURE MOTIF ---------- */
  .chalk-mark{ filter:url(#chalkTexture); }
  .divider-mark{
    display:flex; justify-content:center; margin:0 auto 46px;
    width:64px; opacity:0.85;
  }

  /* ---------- BOOK SECTION ---------- */
  .book-grid{
    display:grid; grid-template-columns:0.85fr 1.15fr; gap:64px; align-items:start;
  }
  @media (max-width:860px){ .book-grid{grid-template-columns:1fr;} }
  .book-covers-stack{
    position:sticky; top:120px;
    display:flex; justify-content:center;
    padding:10px 0 30px 46px;
  }
  .book-covers-stack img{
    width:78%;
    border-radius:2px;
    box-shadow:0 24px 50px -18px rgba(31,59,50,0.55);
  }
  .book-covers-stack .cover-back{
    position:absolute;
    transform:translate(46px, 26px);
    filter:brightness(0.82);
    z-index:1;
  }
  .book-covers-stack .cover-front{
    position:relative;
    z-index:2;
    border:1px solid rgba(255,255,255,0.5);
  }
  .cover-caption{
    font-family:var(--mono); font-size:0.7rem; letter-spacing:0.1em;
    text-transform:uppercase; color:#6b6252; text-align:center;
    margin-top:16px;
  }
  @media (max-width:860px){
    .book-covers-stack{position:static; padding-left:34px;}
  }

  h2{font-size:clamp(1.8rem, 3.4vw, 2.5rem); color:var(--ink); margin-bottom:22px;}
  .chalkboard-bg h2{color:var(--chalk);}
  .lead-text{font-size:1.08rem; max-width:60ch; color:#3c453f; margin-bottom:24px;}
  .pull-quote{
    font-family:var(--serif); font-style:italic; font-size:1.3rem;
    color:var(--ink); border-left:3px solid var(--chalk-yellow);
    padding:4px 0 4px 24px; margin:34px 0 0; max-width:52ch;
  }

  /* ---------- AUTHOR SECTION ---------- */
  .author-grid{
    display:grid; grid-template-columns:220px 1fr; gap:56px; align-items:start;
  }
  @media (max-width:760px){ .author-grid{grid-template-columns:1fr; justify-items:center; text-align:center;} }
  .monogram{
    width:180px; height:180px; border-radius:50%;
    border:1.5px solid var(--chalk-yellow);
    display:flex; align-items:center; justify-content:center;
    font-family:var(--serif); font-style:italic; font-size:2.1rem;
    color:var(--chalk-yellow); position:relative; flex-shrink:0;
  }
  .monogram::before{
    content:""; position:absolute; inset:-14px;
    border:1px dashed rgba(228,190,104,0.35); border-radius:50%;
  }
  .author-grid .pull-quote{color:var(--chalk); border-left-color:var(--chalk-yellow);}
  .author-grid .lead-text{color:rgba(243,238,225,0.86);}

  /* ---------- ACQUIRE SECTION ---------- */
  .acquire-card{
    background:var(--chalkboard);
    color:var(--chalk);
    border-radius:3px;
    padding:56px;
    display:grid; grid-template-columns:1.2fr auto; gap:40px; align-items:center;
    box-shadow:0 30px 60px -25px rgba(31,59,50,0.45);
  }
  @media (max-width:700px){
    .acquire-card{grid-template-columns:1fr; text-align:center; padding:40px 26px;}
  }
  .acquire-card h3{font-size:1.7rem; margin-bottom:10px; color:var(--chalk);}
  .acquire-card p{color:rgba(243,238,225,0.82); max-width:44ch;}
  .volumes{
    display:flex; gap:10px; margin-top:18px; flex-wrap:wrap;
  }
  @media (max-width:700px){ .volumes{justify-content:center;} }
  .volume-chip{
    font-family:var(--mono); font-size:0.75rem; letter-spacing:0.06em;
    border:1px solid rgba(228,190,104,0.5); color:var(--chalk-yellow);
    padding:6px 14px; border-radius:20px;
  }
  .volume-chip.pending{
    opacity:0.6; border-style:dashed;
  }

  .store-grid{
    margin-top:44px; padding-top:36px;
    border-top:1px solid rgba(243,238,225,0.14);
    display:grid; grid-template-columns:1fr 1fr; gap:24px;
  }
  @media (max-width:700px){ .store-grid{grid-template-columns:1fr;} }
  .store-panel{
    background:rgba(243,238,225,0.05);
    border:1px solid rgba(243,238,225,0.14);
    border-radius:3px; padding:22px 24px;
  }
  .store-panel .store-name{
    font-family:var(--mono); font-size:0.68rem; letter-spacing:0.14em;
    text-transform:uppercase; color:var(--chalk-yellow); margin-bottom:14px;
  }
  .store-links{display:flex; flex-direction:column; gap:10px;}
  .store-link{
    display:flex; align-items:center; justify-content:space-between;
    gap:10px; padding:12px 16px;
    background:rgba(243,238,225,0.06);
    border:1px solid rgba(243,238,225,0.14);
    border-radius:3px; text-decoration:none; color:var(--chalk);
    font-size:0.92rem; font-weight:600;
    transition:background 0.18s ease, border-color 0.18s ease, transform 0.18s ease;
  }
  .store-link:hover{
    background:rgba(228,190,104,0.12);
    border-color:rgba(228,190,104,0.5);
    transform:translateX(3px);
  }
  .store-link span.arrow{color:var(--chalk-yellow); font-family:var(--mono);}

  /* ---------- CONTACT / FOOTER ---------- */
  footer.contact{
    background:var(--chalkboard-2); color:var(--chalk);
    padding:86px 0 40px;
  }
  .contact-grid{
    display:grid; grid-template-columns:1fr 1fr; gap:40px;
    padding-bottom:50px; border-bottom:1px solid rgba(243,238,225,0.12);
  }
  @media (max-width:700px){ .contact-grid{grid-template-columns:1fr; gap:34px;} }
  .contact-grid h4{
    font-family:var(--mono); font-size:0.72rem; letter-spacing:0.16em;
    text-transform:uppercase; color:var(--chalk-yellow); margin-bottom:14px;
  }
  .contact-grid a.email{
    font-family:var(--serif); font-size:1.3rem; font-style:italic;
    color:var(--chalk); text-decoration:none; border-bottom:1px solid transparent;
  }
  .contact-grid a.email:hover{border-bottom-color:var(--chalk-yellow);}
  .social-list{display:flex; gap:22px; flex-wrap:wrap;}
  .social-list a{
    display:flex; align-items:center; gap:8px;
    text-decoration:none; color:var(--chalk); font-size:0.95rem; font-weight:600;
    opacity:0.85;
  }
  .social-list a:hover{opacity:1; color:var(--chalk-yellow);}
  .social-list svg{width:18px; height:18px;}

  .fine-print{
    display:flex; justify-content:space-between; align-items:center;
    flex-wrap:wrap; gap:12px;
    padding-top:28px; font-family:var(--mono); font-size:0.72rem;
    color:rgba(243,238,225,0.5);
  }

  .reveal{
    opacity:0; transform:translateY(18px);
    transition:opacity 0.7s ease, transform 0.7s ease;
  }
  .reveal.in{opacity:1; transform:none;}

  /* ---------- COLEÇÃO COMPLETA (3 VOLUMES) ---------- */
  .collection{
    margin-top:96px;
    padding-top:72px;
    border-top:1px solid var(--paper-line);
  }
  .collection-head{
    max-width:56ch; margin-bottom:44px;
  }
  .collection-head h2{margin-bottom:12px;}
  .collection-head p{color:#3c453f; font-size:1.02rem;}
  .collection-grid{
    display:grid; grid-template-columns:repeat(auto-fit, minmax(230px, 1fr)); gap:28px;
  }
  @media (max-width:860px){ .collection-grid{grid-template-columns:1fr; max-width:340px; margin:0 auto;} }
  .vol-card{
    background:var(--chalkboard);
    border-radius:3px; overflow:hidden;
    display:flex; flex-direction:column;
    box-shadow:0 20px 40px -22px rgba(31,59,50,0.5);
    transition:transform 0.25s ease;
  }
  .vol-card:hover{transform:translateY(-6px);}
  .vol-card .vol-thumb{
    aspect-ratio:3/4; overflow:hidden; position:relative;
    background:var(--chalkboard-2);
  }
  .vol-card .vol-thumb img{
    width:100%; height:100%; object-fit:cover; display:block;
  }
  .vol-card .vol-status{
    position:absolute; top:12px; right:12px;
    font-family:var(--mono); font-size:0.62rem; letter-spacing:0.1em;
    text-transform:uppercase; padding:5px 10px; border-radius:20px;
    background:rgba(228,190,104,0.92); color:#221a06;
  }
  .vol-card .vol-status.pending{
    background:rgba(243,238,225,0.14); color:var(--chalk);
    border:1px solid rgba(228,190,104,0.5);
  }
  .vol-card .vol-body{
    padding:20px 22px 24px;
  }
  .vol-card .vol-eyebrow{
    font-family:var(--mono); font-size:0.66rem; letter-spacing:0.14em;
    text-transform:uppercase; color:var(--chalk-yellow); margin-bottom:6px;
  }
  .vol-card h3{
    font-size:1.2rem; color:var(--chalk); margin-bottom:8px;
  }
  /* ---------- LINHA DO TEMPO — HISTÓRIA DA MATEMÁTICA ---------- */
  .timeline{
    display:flex; flex-direction:column; gap:0;
  }
  .timeline-item{
    display:grid; grid-template-columns:110px 1fr; gap:32px;
    padding:30px 0; border-top:1px solid var(--paper-line);
  }
  .timeline-item:first-child{ border-top:none; }
  .timeline-era{
    font-family:var(--mono); font-size:0.82rem; color:#8a7a3f;
    letter-spacing:0.03em; padding-top:4px;
  }
  .timeline-item h3{
    font-family:var(--serif); font-size:1.3rem; margin-bottom:8px; color:var(--ink);
  }
  .timeline-item p{ color:#3c453f; max-width:65ch; }
  @media (max-width:640px){
    .timeline-item{ grid-template-columns:1fr; gap:6px; }
  }

  /* ---------- VERTICAL BOOK LIST (coluna única, capa + descrição lado a lado) ---------- */
  .book-list{
    display:flex; flex-direction:column; gap:44px;
  }
  .book-row{
    display:grid; grid-template-columns:180px 1fr; gap:36px; align-items:center;
    background:var(--paper); border:1px solid var(--paper-line); border-radius:6px;
    padding:26px; box-shadow:0 14px 30px -20px rgba(31,59,50,0.35);
  }
  .book-row .row-thumb{
    position:relative; display:flex; align-items:center; justify-content:center;
  }
  .book-row .row-thumb img{
    width:100%; border-radius:2px; box-shadow:0 16px 28px -14px rgba(31,59,50,0.5);
  }
  .book-row .row-thumb-placeholder{
    width:100%; aspect-ratio:2/3; border-radius:2px;
    background:var(--chalkboard); display:flex; align-items:center; justify-content:center;
    box-shadow:0 16px 28px -14px rgba(31,59,50,0.5);
  }
  .book-row .row-status{
    position:absolute; top:8px; left:8px;
    font-family:var(--mono); font-size:0.62rem; letter-spacing:0.06em; text-transform:uppercase;
    background:var(--chalk-yellow); color:var(--ink); padding:3px 8px; border-radius:3px;
  }
  .book-row .row-status.pending{ background:var(--chalk-blue); }
  .book-row .row-eyebrow{
    font-family:var(--mono); font-size:0.7rem; letter-spacing:0.1em; text-transform:uppercase;
    color:#8a7a3f; margin-bottom:6px;
  }
  .book-row h3{
    font-family:var(--serif); font-size:1.35rem; margin-bottom:10px; color:var(--ink);
  }
  .book-row p.row-desc{
    color:#3c453f; font-size:0.98rem; max-width:60ch;
  }
  @media (max-width:640px){
    .book-row{ grid-template-columns:1fr; text-align:center; }
    .book-row .row-thumb{ max-width:180px; margin:0 auto; }
  }

  .vol-card p.vol-desc{
    font-size:0.9rem; color:rgba(243,238,225,0.78); line-height:1.55;
  }
  .vol-thumb-placeholder{
    width:100%; height:100%;
    display:flex; align-items:center; justify-content:center;
    background:
      radial-gradient(rgba(255,255,255,0.04) 1px, transparent 1px) 0 0/6px 6px,
      var(--chalkboard-2);
  }
  .vol-thumb-placeholder svg{width:56%; opacity:0.75;}

/* ================= NAV SEARCH ================= */
.nav-search{
  position:relative; display:flex; align-items:center;
  margin-right:4px;
}
.nav-search input{
  width:180px; padding:8px 12px 8px 34px;
  background:rgba(243,238,225,0.08);
  border:1px solid rgba(243,238,225,0.22);
  border-radius:20px; color:var(--chalk);
  font-family:var(--sans); font-size:0.85rem;
  transition:width 0.25s ease, background 0.2s ease;
}
.nav-search input::placeholder{color:rgba(243,238,225,0.5);}
.nav-search input:focus{
  width:230px; background:rgba(243,238,225,0.14);
  outline:none; border-color:var(--chalk-yellow);
}
.nav-search svg{
  position:absolute; left:11px; width:15px; height:15px;
  stroke:rgba(243,238,225,0.6); pointer-events:none;
}
.search-results{
  position:absolute; top:calc(100% + 10px); right:0; width:320px;
  background:var(--chalkboard-2); border:1px solid rgba(228,190,104,0.3);
  border-radius:4px; box-shadow:0 20px 40px -14px rgba(0,0,0,0.5);
  max-height:360px; overflow-y:auto; display:none; z-index:200;
}
.search-results.open{display:block;}
.search-results a{
  display:block; padding:12px 16px; text-decoration:none;
  border-bottom:1px solid rgba(243,238,225,0.08);
}
.search-results a:last-child{border-bottom:none;}
.search-results a:hover{background:rgba(228,190,104,0.1);}
.search-results .sr-title{
  font-family:var(--sans); font-weight:700; font-size:0.9rem; color:var(--chalk);
  margin-bottom:3px;
}
.search-results .sr-snippet{
  font-family:var(--sans); font-size:0.78rem; color:rgba(243,238,225,0.65);
}
.search-results .sr-empty{
  padding:16px; font-family:var(--mono); font-size:0.8rem;
  color:rgba(243,238,225,0.55);
}
@media (max-width:760px){
  .nav-search{order:3; width:100%; margin:14px 28px 4px;}
  .nav-search input{width:100%;}
  .nav-search input:focus{width:100%;}
  .search-results{width:100%; left:0; right:0;}
}

/* nav active state */
nav.main-links a.active{opacity:1;}
nav.main-links a.active::after{width:100%;}

/* ================= NEWSLETTER BAND ================= */
.newsletter-band{
  background:var(--chalkboard-2);
  padding:64px 0;
  border-top:1px solid rgba(243,238,225,0.1);
  border-bottom:1px solid rgba(243,238,225,0.1);
}
.newsletter-inner{
  display:flex; align-items:center; justify-content:space-between;
  gap:36px; flex-wrap:wrap;
}
.newsletter-copy{max-width:46ch;}
.newsletter-copy p.eyebrow{margin-bottom:10px;}
.newsletter-copy h3{
  font-family:var(--serif); font-size:1.5rem; color:var(--chalk); margin-bottom:8px;
}
.newsletter-copy p.sub{color:rgba(243,238,225,0.75); font-size:0.95rem;}
.newsletter-form{
  display:flex; gap:10px; flex-wrap:wrap; min-width:320px;
}
.newsletter-form input[type="email"]{
  flex:1; min-width:220px; padding:14px 18px;
  background:rgba(243,238,225,0.08); border:1px solid rgba(243,238,225,0.25);
  border-radius:3px; color:var(--chalk); font-family:var(--sans); font-size:0.95rem;
}
.newsletter-form input[type="email"]::placeholder{color:rgba(243,238,225,0.45);}
.newsletter-form input[type="email"]:focus{outline:none; border-color:var(--chalk-yellow);}
.newsletter-form button{
  font-family:var(--sans); font-weight:700; font-size:0.92rem;
  padding:14px 24px; background:var(--chalk-yellow); color:#221a06;
  border:none; border-radius:3px; cursor:pointer; white-space:nowrap;
  transition:transform 0.18s ease;
}
.newsletter-form button:hover{transform:translateY(-2px);}
.newsletter-note{
  font-family:var(--mono); font-size:0.7rem; color:rgba(243,238,225,0.45);
  margin-top:10px; width:100%;
}
.newsletter-status{
  font-family:var(--sans); font-size:0.85rem; margin-top:10px; width:100%;
  display:none;
}
.newsletter-status.show{display:block;}
.newsletter-status.ok{color:#9fd4a3;}
.newsletter-status.err{color:#e0a3a3;}

/* ================= PAGE HERO (subpáginas) ================= */
.page-hero{
  padding:150px 0 70px;
}
.page-hero h1{
  font-size:clamp(2rem, 4.4vw, 3rem); color:var(--chalk); margin-bottom:14px;
}
.page-hero p.sub{color:rgba(243,238,225,0.8); max-width:56ch; font-size:1.05rem;}
.breadcrumb{
  font-family:var(--mono); font-size:0.72rem; letter-spacing:0.08em;
  color:rgba(243,238,225,0.55); margin-bottom:18px;
}
.breadcrumb a{color:var(--chalk-yellow); text-decoration:none;}
.breadcrumb a:hover{text-decoration:underline;}