:root { --blue:#D80000; --navy:#1A1A1A; --ink:#1a1a2e; --gray:#595959; --bg:#F4F6FB; --amber:#C4A464; }
* { box-sizing:border-box; margin:0; padding:0; }
body { font-family:Arial, Helvetica, sans-serif; color:var(--ink); line-height:1.55; }
.container { max-width:1060px; margin:0 auto; padding:0 24px; }
nav { background:#fff; border-bottom:1px solid #e5e9f2; position:sticky; top:0; z-index:10; }
nav .container { display:flex; align-items:center; justify-content:space-between; height:64px; }
.logo { font-weight:bold; font-size:17px; color:var(--navy); text-decoration:none; }
.logo span { color:var(--blue); }
nav ul { display:flex; gap:22px; list-style:none; font-size:14px; align-items:center; }
nav a { color:var(--ink); text-decoration:none; }
.nav-toggle {
  display:none;
  align-items:center;
  justify-content:center;
  width:44px;
  height:44px;
  padding:0;
  border:1px solid #e5e9f2;
  border-radius:8px;
  background:#fff;
  cursor:pointer;
  flex-shrink:0;
}
.nav-toggle-bar,
.nav-toggle-bar::before,
.nav-toggle-bar::after {
  display:block;
  width:20px;
  height:2px;
  background:var(--navy);
  border-radius:1px;
  transition:transform .2s ease, opacity .2s ease;
}
.nav-toggle-bar {
  position:relative;
}
.nav-toggle-bar::before,
.nav-toggle-bar::after {
  content:"";
  position:absolute;
  left:0;
}
.nav-toggle-bar::before { top:-6px; }
.nav-toggle-bar::after { top:6px; }
.nav-open .nav-toggle-bar { background:transparent; }
.nav-open .nav-toggle-bar::before { top:0; transform:rotate(45deg); }
.nav-open .nav-toggle-bar::after { top:0; transform:rotate(-45deg); }
.nav-menu .nav-cta .btn { padding:8px 16px; }
.hero-grid { display:grid; grid-template-columns:1.25fr .75fr; gap:44px; align-items:center; }
.hero-grid--book { grid-template-columns:1fr 220px; gap:36px; }
.btn-row { display:flex; gap:14px; flex-wrap:wrap; }
.btn { display:inline-block; background:var(--blue); color:#fff !important; padding:11px 22px; border-radius:8px; font-weight:bold; text-decoration:none; font-size:15px; border:none; cursor:pointer; }
.btn.ghost { background:transparent; color:var(--blue) !important; border:2px solid var(--blue); }
.btn.amber { background:var(--amber); color:#1A1A1A !important; }
.hero { background:#161616; border-bottom:4px solid var(--blue); color:#fff; padding:64px 0 58px; }
.hero h1 { font-size:36px; line-height:1.15; max-width:760px; }
.hero p { margin:18px 0 26px; font-size:17px; color:#dbe6f3; max-width:680px; }
.hero.short { padding:48px 0 42px; }
.mathbar { background:var(--navy); color:#fff; text-align:center; padding:16px 24px; font-size:15.5px; }
.mathbar b { color:var(--amber); }
section { padding:58px 0; }
section.alt { background:var(--bg); }
h2 { font-size:27px; color:var(--navy); margin-bottom:10px; }
h3 { font-size:17px; color:var(--blue); margin-bottom:6px; }
.lead { color:var(--gray); font-size:15.5px; max-width:720px; }
.cols { display:grid; grid-template-columns:repeat(auto-fit,minmax(240px,1fr)); gap:22px; margin-top:30px; }
.col { background:#fff; border:1px solid #e5e9f2; border-radius:10px; padding:22px; }
.col p { font-size:14px; color:var(--gray); }
.part { margin-top:26px; }
.part h3 { font-size:15px; letter-spacing:1px; text-transform:uppercase; }
.ch { display:flex; gap:14px; padding:10px 0; border-bottom:1px solid #edf0f6; font-size:14.5px; }
.ch b { color:var(--blue); min-width:64px; }
.tool { display:grid; grid-template-columns:1fr auto; gap:30px; align-items:center; background:var(--navy); color:#fff; border-radius:14px; padding:32px 36px; }
.tool h2 { color:#fff; } .tool p { color:#dbe6f3; font-size:15px; max-width:560px; margin-top:8px; }
.bio { display:grid; grid-template-columns:170px minmax(0,1fr); gap:26px; margin-top:30px; align-items:start; }
.avatar { width:150px; height:150px; border-radius:50%; background:var(--bg); border:3px solid var(--blue); display:flex; align-items:center; justify-content:center; font-weight:bold; font-size:28px; color:var(--blue); }
.bio p { font-size:14.5px; color:var(--ink); margin-top:6px; }
form { max-width:560px; }
label { display:block; font-weight:bold; font-size:14px; margin:12px 0 4px; }
input, select, textarea { width:100%; padding:11px; border:1px solid #ccd4e4; border-radius:6px; font-size:14px; font-family:inherit; }
.notice { background:var(--bg); border-radius:8px; padding:14px 18px; font-size:13.5px; color:var(--gray); margin-top:16px; }
.ok { background:#E8F5E9; border:1px solid #A5D6A7; border-radius:8px; padding:16px 18px; font-size:14px; margin-top:16px; display:none; }
footer { background:var(--navy); color:#b9c9dc; padding:32px 0; font-size:13px; }
footer .container { display:flex; justify-content:space-between; flex-wrap:wrap; gap:10px; }
footer a { color:#dbe6f3; }
@media (max-width:760px) {
  .container { padding:0 18px; }
  nav .container {
    flex-wrap:wrap;
    height:auto;
    min-height:56px;
    padding-top:10px;
    padding-bottom:10px;
    gap:0;
  }
  .nav-toggle { display:flex; margin-left:auto; }
  .nav-menu {
    display:none;
    flex-direction:column;
    align-items:stretch;
    gap:0;
    width:100%;
    margin-top:12px;
    padding:8px 0 4px;
    border-top:1px solid #e5e9f2;
  }
  .nav-open .nav-menu { display:flex; }
  .nav-menu li { width:100%; }
  .nav-menu a {
    display:block;
    padding:12px 4px;
    font-size:15px;
  }
  .nav-menu .nav-cta { margin-top:8px; padding-top:8px; border-top:1px solid #e5e9f2; }
  .nav-menu .nav-cta .btn {
    display:block;
    width:100%;
    text-align:center;
    padding:12px 16px;
  }
  body.nav-no-scroll { overflow:hidden; }
  .hero { padding:40px 0 36px; }
  .hero.short { padding:36px 0 30px; }
  .hero h1 { font-size:26px; line-height:1.2; max-width:none; }
  .hero p { font-size:16px; margin:14px 0 20px; max-width:none; }
  .hero-grid,
  .hero-grid--book,
  .hero .container[style] {
    display:flex !important;
    flex-direction:column;
    gap:28px !important;
  }
  .hero .coverimg {
    max-width:min(260px, 72vw);
    margin:0 auto;
  }
  .mathbar { font-size:14px; line-height:1.45; padding:14px 18px; }
  section { padding:40px 0; }
  h2 { font-size:23px; }
  .tool {
    grid-template-columns:1fr;
    gap:20px;
    padding:24px 20px;
    text-align:center;
  }
  .tool p { max-width:none; margin-left:auto; margin-right:auto; }
  .tool .btn { width:100%; text-align:center; }
  .bio { grid-template-columns:1fr; text-align:center; }
  .bio .avatar,
  .bio .headshot { margin:0 auto; display:block; }
  footer .container {
    flex-direction:column;
    align-items:center;
    text-align:center;
    gap:14px;
  }
  .btn-row { flex-direction:column; align-items:stretch; }
  .btn-row .btn { width:100%; text-align:center; }
  #buy .btn-row { max-width:320px; margin:0 auto; }
}

/* --- image styling (2026-07-06) --- */
.coverimg { width:100%; max-width:340px; border-radius:4px; box-shadow:0 18px 45px rgba(0,0,0,.35); display:block; }
.headshot { width:150px; height:150px; border-radius:50%; object-fit:cover; border:4px solid var(--bg); box-shadow:0 4px 14px rgba(0,0,0,.15); }
.figwrap { background:#fff; border:1px solid #e5e9f2; border-radius:12px; padding:18px; margin-top:26px; }
.figwrap img { width:100%; height:auto; display:block; border-radius:6px; }
.figcap { font-size:12.5px; color:var(--gray); margin-top:10px; text-align:center; }
:root { --gold:#C4A464; }
.btn.amber { background:var(--gold); color:#1A1A1A !important; }
.mathbar b { color:var(--gold); }

.bio > div { min-width:0; }
@media (max-width:760px){ .headshot { margin:0 auto; } }

/* --- cover sticker --- */
.coverwrap { position:relative; display:inline-block; }
.sticker { position:absolute; top:-34px; right:-30px; width:118px; transform:rotate(12deg); filter:drop-shadow(0 6px 12px rgba(0,0,0,.35)); }
.legal { font-size:12px; }