/* 1. SITE COLORS AND BASICS — edit these variables to change the theme. */
:root {
    --bg-base: #111b3d;
    --card-bg: rgba(10,15,30,.65);
    --accent-glow: #38bdf8;
    --btn-accent: #f97316;
    --text-main: #f8fafc;
    --text-muted: #c0cbdd;
    --border-subtle: rgba(255,255,255,.12);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 130px; }
body {
    margin: 0; color: var(--text-main); line-height: 1.65;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background: radial-gradient(ellipse at 0 0, #233f88, transparent 65%), #10192f;
    background-attachment: fixed;
}
a { color: var(--accent-glow); text-underline-offset: 4px; }
img, video { max-width: 100%; }
button, input, select { font: inherit; }
:focus-visible { outline: 3px solid #fbbf24; outline-offset: 5px; }
.container { width: calc(100% - 40px); max-width: 1200px; margin-left: auto; margin-right: auto; }
main { padding-bottom: 75px; }
/* 2. SHARED NAVIGATION AND FOOTER */
.eyebrow-strip { background: #060d20; padding: 8px 20px; text-align: center; font-size: .8rem; }
.global-site-header { position: sticky; top: 0; z-index: 100; background: rgba(14,23,47,.97); border-bottom: 1px solid var(--border-subtle); }
.primary-navigation { display: flex; align-items: center; justify-content: space-between; gap: 25px; padding: 17px 0; }
.brand-logo { color: #fff; font-weight: 850; line-height: 1.2; text-decoration: none; font-size: 1.1rem; }
.brand-logo span { color: var(--accent-glow); }
.nav-links { display: flex; list-style: none; gap: 22px; align-items: center; margin: 0; padding: 0; }
.nav-links a { color: #e2e8f0; font-size: .9rem; font-weight: 650; text-decoration: none; }
.nav-links a:hover, .nav-links a[aria-current] { color: #67d6ff; text-decoration: underline; }
.nav-buy { border: 1px solid var(--accent-glow); border-radius: 6px; padding: 9px 13px; display: inline-block; }
.menu-toggle { border: 1px solid var(--accent-glow); background: transparent; color: white; border-radius: 6px; padding: 9px 14px; }
.skip-link { position: absolute; left: 15px; top: -100px; background: white; color: #111b3d; padding: 12px; z-index: 200; }
.skip-link:focus { top: 5px; }
.global-site-footer { padding: 40px 0; border-top: 1px solid var(--border-subtle); background: #060d1b; text-align: center; }
.global-site-footer strong { font-size: 1.3rem; }
.footer-links { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px 24px; }
.footer-legal { font-size: .85rem; color: var(--text-muted); margin-top: 28px; }
/* 3. SHARED BUTTONS AND PAGE TITLES */
.btn-primary, .btn-outline { display: inline-block; border-radius: 6px; padding: 12px 22px; font-weight: 750; text-align: center; text-decoration: none; }
.btn-primary { background: var(--btn-accent); color: #111827; border: 1px solid var(--btn-accent); }
.btn-primary:hover { background: #fb923c; }
.btn-outline { border: 1px solid var(--accent-glow); color: var(--accent-glow); }
.btn-outline:hover { background: var(--accent-glow); color: #071020; }
.section-header { margin-bottom: 32px; }
.section-header h2 { color: white; font-size: clamp(1.65rem,3vw,2.2rem); line-height: 1.25; }
.page-intro { padding-top: 55px; max-width: 950px; }
.page-intro h1 { font-size: clamp(2.2rem,5vw,3.8rem); line-height: 1.12; margin: 12px 0 20px; }
.page-intro p { color: var(--text-muted); font-size: 1.1rem; }
.page-links { display: flex; gap: 14px; flex-wrap: wrap; margin-top: 25px; }
.notice { padding: 18px 24px; border-left: 3px solid var(--accent-glow); background: rgba(3,7,18,.35); color: var(--text-muted); }
/* 4. BOOK CONTENT — preserved from your original landing page. */

    .book-hero {
        padding: 48px 0 58px;
        border-bottom: 1px solid rgba(255,255,255,0.04);
        background:
            radial-gradient(circle at 78% 20%, rgba(37,99,235,0.12), transparent 32%),
            radial-gradient(circle at 18% 0%, rgba(249,115,22,0.09), transparent 26%),
            var(--bg-base);
    }
    .hero-grid {
        display: grid;
        grid-template-columns: minmax(260px, 380px) 1fr;
        gap: 55px;
        align-items: center;
    }
    .book-cover-wrapper {
        max-width: 360px;
        margin: 0 auto;
        box-shadow: 0 28px 70px -18px rgba(0,0,0,0.8);
        border-radius: 8px;
        border: 1px solid rgba(255,255,255,0.10);
        overflow: hidden;
        transition: transform .35s ease, box-shadow .35s ease;
        background: #fff;
    }
    .book-cover-wrapper:hover {
        transform: translateY(-7px);
        box-shadow: 0 34px 80px -18px rgba(37,99,235,0.28);
    }
    .book-cover-wrapper img { width:100%; display:block; }
    .eyebrow {
        display:inline-flex;
        align-items:center;
        gap:8px;
        padding:7px 13px;
        border-radius:999px;
        border:1px solid rgba(249,115,22,.35);
        background:rgba(249,115,22,.08);
        color:var(--accent-glow);
        font-size:.78rem;
        font-weight:800;
        letter-spacing:.08em;
        text-transform:uppercase;
        margin-bottom:18px;
    }
    .book-title {
        font-size: clamp(2.6rem, 5vw, 4.25rem);
        line-height: 1.02;
        font-weight: 900;
        letter-spacing: -1.5px;
        color:#fff;
        margin:0 0 15px;
    }
    .book-subtitle {
        font-size:1.4rem;
        line-height:1.4;
        color:var(--accent-glow);
        font-weight:700;
        margin:0 0 18px;
    }
    .authors-line {
        color:#fff;
        font-size:1.08rem;
        font-weight:750;
        margin:0 0 22px;
    }
    .authors-line strong { color:#fff; }
    .book-lede {
        color:var(--text-muted);
        font-size:1.12rem;
        line-height:1.75;
        max-width:830px;
        margin:0 0 28px;
    }
    .hero-buttons { display:flex; flex-wrap:wrap; gap:12px; }
    .hero-buttons .btn-outline { margin-left:0 !important; }
    .meta-strip {
        margin-top:28px;
        display:flex;
        flex-wrap:wrap;
        gap:9px;
    }
    .meta-chip {
        padding:8px 11px;
        border:1px solid rgba(148,163,184,.22);
        border-radius:7px;
        color:var(--text-muted);
        background:rgba(15,23,42,.45);
        font-size:.82rem;
    }
    .section-shell { margin-top:70px; }
    .section-header.center { text-align:center; }
    .section-header.center p { max-width:820px; margin:10px auto 0; color:var(--text-muted); }
    .two-col-copy {
        display:grid;
        grid-template-columns:repeat(2,minmax(0,1fr));
        gap:35px;
        margin-top:32px;
        color:var(--text-main);
        font-size:1.04rem;
        line-height:1.72;
    }
    .highlight-panel {
        display:grid;
        grid-template-columns:1.15fr .85fr;
        gap:32px;
        background:linear-gradient(135deg,rgba(15,23,42,.78),rgba(3,7,18,.90));
        border:1px solid rgba(71,85,105,.3);
        border-radius:16px;
        padding:38px;
        margin-top:34px;
        align-items:center;
    }
    .highlight-panel h3 { margin-top:0; color:#fff; font-size:1.8rem; }
    .highlight-panel p { color:var(--text-muted); line-height:1.7; }
    .highlight-panel img { width:100%; border-radius:10px; border:1px solid rgba(255,255,255,.08); }
    .book-highlights-grid {
        display:grid;
        grid-template-columns:repeat(auto-fit,minmax(240px,1fr));
        gap:20px;
        margin-top:34px;
    }
    .book-highlight-card {
        background:rgba(17,19,36,.48);
        border:1px solid rgba(71,85,105,.24);
        border-radius:12px;
        padding:24px;
    }
    .book-highlight-card strong {
        display:block;
        color:#fff;
        font-size:1.08rem;
        margin-bottom:8px;
    }
    .book-highlight-card p {
        color:var(--text-muted);
        line-height:1.58;
        margin:0;
    }
    .media-grid {
        display:grid;
        grid-template-columns:repeat(2,minmax(0,1fr));
        gap:26px;
        margin-top:35px;
    }
    .media-card {
        background:rgba(17,19,36,.45);
        border:1px solid rgba(71,85,105,.22);
        padding:26px;
        border-radius:12px;
        backdrop-filter:blur(10px);
        display:flex;
        flex-direction:column;
        gap:18px;
    }
    .media-card h3 {
        margin:0;
        padding-bottom:11px;
        border-bottom:2px solid var(--accent-glow);
        color:#fff;
        font-size:1.25rem;
    }
    .media-card p { color:var(--text-muted); margin:0; line-height:1.55; }
    .audio-meta { display:flex; gap:16px; align-items:center; }
    .audio-cover { width:104px; height:104px; object-fit:cover; border-radius:7px; border:1px solid rgba(255,255,255,.1); }
    .audio-banner { width:100%; aspect-ratio:16/9; object-fit:cover; border-radius:9px; border:1px solid rgba(255,255,255,.1); display:block; }
    .audio-player-container audio { width:100%; display:block; }
    .framework-grid {
        display:grid;
        grid-template-columns:repeat(auto-fit,minmax(280px,1fr));
        gap:23px;
        margin-top:38px;
    }
    .framework-card {
        background:rgba(17,19,36,.5);
        border:1px solid rgba(71,85,105,.22);
        padding:27px;
        border-radius:12px;
    }
    .framework-card h4 {
        color:#fff;
        font-size:1.18rem;
        margin:0 0 13px;
        border-bottom:2px solid var(--accent-glow);
        padding-bottom:11px;
    }
    .framework-card p { margin-bottom:0; color:var(--text-muted); line-height:1.6; }
    .authors-grid {
        display:grid;
        grid-template-columns:repeat(2,minmax(0,1fr));
        gap:25px;
        margin-top:32px;
    }
    .author-card {
        background:linear-gradient(135deg,rgba(15,23,42,.72),rgba(3,7,18,.88));
        border:1px solid rgba(71,85,105,.3);
        border-radius:14px;
        padding:30px;
    }
    .author-card h3 { color:#fff; margin:0 0 7px; font-size:1.5rem; }
    .author-role { color:var(--accent-glow); font-weight:700; font-size:.93rem; margin-bottom:15px; }
    .author-card p { color:var(--text-muted); line-height:1.67; }
    .together-box {
        margin-top:24px;
        padding:24px 28px;
        border-radius:12px;
        border:1px solid rgba(37,99,235,.24);
        background:rgba(37,99,235,.06);
        color:var(--text-main);
        line-height:1.65;
        text-align:center;
    }
    .id-grid {
        display:grid;
        grid-template-columns:repeat(auto-fit,minmax(190px,1fr));
        gap:15px;
        margin-top:28px;
    }
    .id-card {
        padding:18px;
        background:rgba(17,19,36,.45);
        border:1px solid rgba(71,85,105,.22);
        border-radius:10px;
        text-align:center;
    }
    .id-card small { display:block; color:var(--text-muted); text-transform:uppercase; letter-spacing:.08em; margin-bottom:6px; }
    .id-card strong { color:#fff; font-family:'Roboto Mono',monospace; font-size:.95rem; }
    .infographic-wrap { margin-top:34px; }
    .infographic-wrap img { width:100%; border-radius:12px; border:1px solid rgba(255,255,255,.08); display:block; }

    .calc-container { display:grid; grid-template-columns:1fr; gap:30px; margin-top:35px; text-align:left; }
    @media (min-width:768px){ .calc-container{grid-template-columns:400px 1fr;} }
    .calc-form { background:rgba(0,0,0,.25); padding:25px; border-radius:8px; border:1px solid rgba(255,255,255,.05); }
    .calc-group { margin-bottom:20px; }
    .calc-group label { display:block; font-size:.9rem; font-weight:600; margin-bottom:8px; color:#fff; }
    .calc-input { width:100%; padding:12px; background:rgba(255,255,255,.05); border:1px solid rgba(71,85,105,.4); border-radius:6px; color:#fff; box-sizing:border-box; font-size:1rem; }
    .calc-input:focus { border-color:var(--accent-glow); outline:none; }
    .calc-results { display:grid; grid-template-columns:repeat(auto-fit,minmax(180px,1fr)); gap:20px; }
    .calc-card { background:var(--card-bg); border:1px solid rgba(71,85,105,.3); border-radius:8px; padding:20px; text-align:center; }
    .calc-card h5 { margin:0 0 10px; font-size:.85rem; text-transform:uppercase; color:var(--text-muted); letter-spacing:1px; }
    .calc-val { font-size:1.8rem; font-weight:800; color:#fff; font-family:'Roboto Mono',monospace; }
    .calc-verdict { grid-column:1/-1; padding:20px; border-radius:6px; background:rgba(56,189,248,.08); border:1px solid rgba(56,189,248,.3); color:#c8eaff; font-size:.95rem; line-height:1.5; display:none; }
    .calc-verdict.active { display:block; }

    @media (max-width:900px){
        .hero-grid,.highlight-panel,.two-col-copy,.authors-grid,.media-grid { grid-template-columns:1fr; }
        .hero-copy { text-align:center; }
        .hero-buttons,.meta-strip { justify-content:center; }
        .book-cover-wrapper { max-width:315px; }
    }

/* 5. RESPONSIVE AND ACCESSIBILITY ADJUSTMENTS */
.book-hero { background-image: linear-gradient(rgba(255,255,255,.035) 1px, transparent 1px), linear-gradient(90deg,rgba(255,255,255,.035) 1px,transparent 1px); background-size: 40px 40px; }
.book-cover-wrapper { width: 100%; }
.book-title { overflow-wrap: anywhere; }
.calc-input option { background: #14203a; color: white; }
.calc-container { grid-template-columns: minmax(230px,.85fr) minmax(0,1.3fr); }
.calc-results { grid-template-columns: repeat(3,minmax(0,1fr)); }
.calc-val { font-size: clamp(1.1rem,2.3vw,1.8rem); overflow-wrap: anywhere; }
.calc-card { padding: 18px 10px; }
.calculator-shell { padding: 30px; background: rgba(17,19,36,.4); border-radius: 16px; border: 1px solid var(--border-subtle); }
.calculator-note { color: var(--text-muted); font-size: .9rem; }
.media-card audio, .media-card video { width: 100%; }
.media-card img { object-fit: contain; }
.media-card .media-status { color: #fbbf24; font-size: .9rem; }
.section-shell > h2 { font-size: 2rem; }
[hidden] { display: none !important; }
@media (min-width: 901px) { .menu-toggle { display: none; } }
@media (max-width: 900px) {
    .primary-navigation { flex-wrap: wrap; }
    .nav-links { width: 100%; flex-wrap: wrap; gap: 15px; }
    .nav-links.menu-closed { display: none; }
    .book-title { font-size: clamp(2.2rem,7vw,3.5rem); }
    .calc-container { grid-template-columns: 1fr; }
}
@media (max-width: 540px) {
    .container { width: calc(100% - 28px); }
    .section-shell { margin-top: 45px; }
    .highlight-panel, .media-card, .author-card, .framework-card { padding: 22px; }
    .framework-grid, .book-highlights-grid { grid-template-columns: 1fr; }
    .hero-buttons { flex-direction: column; }
    .calculator-shell { padding: 18px; }
    .calc-form { padding: 17px; }
    .calc-results { grid-template-columns: 1fr; }
    .book-subtitle { font-size: 1.16rem; }
}
@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after { animation: none !important; transition: none !important; }
}
@media print {
    body { background: white; color: black; }
    .global-site-header, .eyebrow-strip, .global-site-footer, .hero-buttons, audio, video { display: none; }
    p, h1, h2, h3, h4, strong, .calc-val { color: black !important; }
    .container { width: 100%; }
}