/* ==========================================================================
   The AI Tutor Vault — single-page sales site
   Vanilla CSS. No framework, no build step, no web fonts (zero blocking
   requests: everything renders on first paint).
   ========================================================================== */

:root{
    --paper:#FBFAF7;
    --paper-2:#F3F1EA;
    --surface:#FFFFFF;

    --ink:#16181D;
    --body:#474D57;
    --muted:#767C87;

    --line:rgba(22,24,29,.10);
    --line-2:rgba(22,24,29,.18);

    --accent:#1D4E7C;          /* deep blue — trust, education */
    --accent-ink:#143A5E;
    --accent-soft:#E8EFF6;

    --warm:#B4642A;            /* terracotta — highlights */
    --warm-soft:#FBF0E6;

    --good:#1F7A4D;
    --good-soft:#E8F3ED;
    --bad:#A8433A;
    --bad-soft:#F8ECEA;

    --r:12px;
    --r-lg:18px;
    --wrap:1080px;

    --serif:"Iowan Old Style","Palatino Linotype",Palatino,Georgia,"Times New Roman",serif;
    --sans:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
    --mono:ui-monospace,SFMono-Regular,Menlo,Consolas,"Liberation Mono",monospace;
}

*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}

html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}

body{
    background:var(--paper);
    color:var(--body);
    font-family:var(--sans);
    font-size:17px;
    line-height:1.65;
    -webkit-font-smoothing:antialiased;
    overflow-x:hidden;
}

img{max-width:100%;height:auto;display:block}

h1,h2,h3{color:var(--ink);font-family:var(--serif);font-weight:600;line-height:1.15;letter-spacing:-.01em}
h1{font-size:clamp(34px,5.2vw,54px)}
h2{font-size:clamp(27px,3.7vw,40px)}
h3{font-size:19px;line-height:1.3}
em{font-style:italic;color:var(--accent)}

a{color:var(--accent);text-decoration-thickness:1px;text-underline-offset:2px}

.wrap{width:100%;max-width:var(--wrap);margin:0 auto;padding:0 22px}

section{padding:clamp(56px,7vw,92px) 0}
section.tight{padding-top:0}

.eyebrow{
    display:inline-block;
    font-size:12.5px;font-weight:700;letter-spacing:.09em;text-transform:uppercase;
    color:var(--warm);margin-bottom:14px;
}

.head{max-width:760px;margin-bottom:44px}
.head.center{margin-left:auto;margin-right:auto;text-align:center}
.head p{margin-top:16px;font-size:18px;color:var(--body)}

.lede{font-size:19px}

/* ---------- buttons ---------------------------------------------------- */

.btn{
    display:inline-flex;align-items:center;justify-content:center;gap:9px;
    background:var(--accent);color:#fff;
    font-family:var(--sans);font-size:16px;font-weight:600;
    padding:15px 26px;border:0;border-radius:var(--r);
    text-decoration:none;cursor:pointer;
    box-shadow:0 1px 2px rgba(20,58,94,.28),0 6px 18px rgba(20,58,94,.20);
    transition:background .15s ease,transform .15s ease,box-shadow .15s ease;
}
.btn:hover{background:var(--accent-ink);transform:translateY(-1px);box-shadow:0 2px 4px rgba(20,58,94,.3),0 10px 24px rgba(20,58,94,.24)}
.btn:active{transform:translateY(0)}
.btn:focus-visible{outline:3px solid var(--warm);outline-offset:3px}
.btn .arrow{transition:transform .15s ease}
.btn:hover .arrow{transform:translateX(3px)}

.btn-lg{font-size:17.5px;padding:18px 34px;width:100%;max-width:420px}
@media(min-width:600px){.btn-lg{width:auto}}

.btn-ghost{
    background:transparent;color:var(--accent);
    border:1px solid var(--line-2);box-shadow:none;font-weight:600;
}
.btn-ghost:hover{background:var(--accent-soft);color:var(--accent-ink);box-shadow:none}

.cta-note{margin-top:14px;font-size:14.5px;color:var(--muted)}

/* ---------- nav -------------------------------------------------------- */

nav{
    position:sticky;top:0;z-index:60;
    background:rgba(251,250,247,.94);
    border-bottom:1px solid var(--line);
}
@supports(backdrop-filter:blur(8px)){nav{backdrop-filter:blur(8px)}}

.nav-row{display:flex;align-items:center;justify-content:space-between;gap:16px;height:62px}

.logo{
    display:flex;align-items:center;gap:9px;
    font-family:var(--serif);font-size:17.5px;font-weight:600;color:var(--ink);
    text-decoration:none;
}
.logo-mark{
    width:22px;height:22px;flex:none;border-radius:5px;
    background:var(--accent);
    display:grid;place-items:center;
    color:#fff;font-family:var(--sans);font-size:12px;font-weight:700;
}

.nav-cta{
    display:inline-flex;align-items:center;gap:8px;
    background:var(--accent);color:#fff;text-decoration:none;
    font-size:14.5px;font-weight:600;padding:10px 18px;border-radius:9px;
    transition:background .15s ease;
}
.nav-cta:hover{background:var(--accent-ink)}
.nav-cta:focus-visible{outline:3px solid var(--warm);outline-offset:2px}

/* ---------- hero ------------------------------------------------------- */

.hero{padding-top:clamp(40px,5vw,64px);padding-bottom:clamp(48px,6vw,80px)}
.hero-grid{display:grid;gap:44px;align-items:center}
@media(min-width:940px){.hero-grid{grid-template-columns:1.08fr .92fr;gap:56px}}

.badge{
    display:inline-flex;align-items:center;gap:9px;
    background:var(--surface);border:1px solid var(--line-2);
    border-radius:999px;padding:7px 15px;
    font-size:13.5px;font-weight:500;color:var(--body);margin-bottom:22px;
}
.badge .dot{width:7px;height:7px;border-radius:50%;background:var(--good);flex:none}

.hero h1{margin-bottom:20px}
.hero-sub{font-size:18.5px;max-width:560px;margin-bottom:26px}
.hero-sub strong{color:var(--ink);font-weight:600}

.price-block{display:flex;align-items:baseline;gap:12px;flex-wrap:wrap;margin-bottom:6px}
.price-now{font-family:var(--serif);font-size:40px;font-weight:600;color:var(--ink);line-height:1}
.price-unit{font-size:15px;color:var(--muted)}
.price-meta{font-size:14.5px;color:var(--muted);margin-bottom:24px}

.hero-cta{margin-bottom:20px}

.trust{
    display:flex;flex-wrap:wrap;align-items:center;gap:8px 14px;
    font-size:14.5px;color:var(--muted);
}
.trust .sep{color:var(--line-2)}

/* book cover ------------------------------------------------------------ */

.cover-stage{display:flex;justify-content:center;position:relative}

.cover{
    width:100%;max-width:340px;
    aspect-ratio:1/1.38;
    background:linear-gradient(160deg,#1B3A5B 0%,#122A44 55%,#0D1F33 100%);
    border-radius:6px 12px 12px 6px;
    padding:34px 28px 26px;
    display:flex;flex-direction:column;
    color:#fff;
    box-shadow:
        -6px 0 0 rgba(255,255,255,.07) inset,
        0 22px 50px rgba(13,31,51,.34),
        0 4px 12px rgba(13,31,51,.2);
}

.cover-eyebrow{font-size:11.5px;font-weight:700;letter-spacing:.12em;text-transform:uppercase;color:#8FB4D6}
.cover-title{font-family:var(--serif);font-size:clamp(30px,4.2vw,38px);line-height:1.08;font-weight:600;margin-top:16px;color:#fff}
.cover-title em{color:#EBBE7E;font-style:italic}
.cover-rule{height:1px;background:rgba(255,255,255,.2);margin:20px 0}
.cover-desc{font-size:13.5px;line-height:1.5;color:#C6D5E4}
.cover-list{list-style:none;margin-top:16px;display:grid;gap:7px}
.cover-list li{display:flex;gap:8px;font-size:12.5px;color:#9DB3C8;line-height:1.4}
.cover-list li::before{content:"✓";color:#7FA9D8;font-weight:700;flex:none}
.cover-foot{
    margin-top:auto;padding-top:20px;
    display:flex;justify-content:space-between;align-items:center;
    font-size:11.5px;color:#7B8FA6;letter-spacing:.04em;
}
.cover-foot .pages{border:1px solid rgba(255,255,255,.18);border-radius:5px;padding:3px 9px}

/* ---------- stat strip ------------------------------------------------- */

.stats{background:var(--paper-2);border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:26px 0}
.stats-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:22px 12px;text-align:center}
@media(min-width:700px){.stats-grid{grid-template-columns:repeat(4,1fr)}}
.stat-n{display:block;font-family:var(--serif);font-size:29px;font-weight:600;color:var(--ink);line-height:1.1}
.stat-l{display:block;font-size:13.5px;color:var(--muted);margin-top:5px}

/* ---------- problem beats ---------------------------------------------- */

.beats{display:grid;gap:18px}
@media(min-width:800px){.beats{grid-template-columns:repeat(3,1fr)}}
.beat{background:var(--surface);border:1px solid var(--line);border-radius:var(--r-lg);padding:28px 26px}
.beat h3{margin-bottom:10px}
.beat p{font-size:15.5px}
.beat-time{
    font-family:var(--mono);font-size:12px;font-weight:600;letter-spacing:.06em;
    color:var(--warm);margin-bottom:12px;display:block;
}

.pullquote{
    max-width:760px;margin:44px auto 0;text-align:center;
    font-family:var(--serif);font-size:clamp(21px,2.7vw,27px);line-height:1.4;color:var(--ink);
}

/* ---------- before / after --------------------------------------------- */

.compare{display:grid;gap:18px}
@media(min-width:840px){.compare{grid-template-columns:1fr 1fr;gap:22px}}

.pane{border-radius:var(--r-lg);border:1px solid var(--line);background:var(--surface);overflow:hidden;display:flex;flex-direction:column}
.pane-head{display:flex;align-items:center;gap:10px;padding:15px 22px;border-bottom:1px solid var(--line);font-size:14px;font-weight:600}
.pane.before .pane-head{background:var(--bad-soft);color:var(--bad)}
.pane.after .pane-head{background:var(--good-soft);color:var(--good)}
.pane-head .tag{margin-left:auto;font-weight:500;font-size:12.5px;opacity:.8}

.chat{padding:22px;display:grid;gap:12px}
.msg{max-width:88%;padding:12px 16px;border-radius:14px;font-size:15px;line-height:1.5}
.msg.kid{background:var(--paper-2);color:var(--ink);border-bottom-left-radius:5px}
.msg.ai{background:var(--accent-soft);color:var(--accent-ink);margin-left:auto;border-bottom-right-radius:5px}
.pane.before .msg.ai{background:var(--bad-soft);color:#7E3129}
.pane.after .msg.ai{background:var(--good-soft);color:#155F3A}
.msg .who{display:block;font-size:11px;font-weight:700;letter-spacing:.07em;text-transform:uppercase;opacity:.62;margin-bottom:4px}

.pane-foot{margin-top:auto;padding:16px 22px;border-top:1px solid var(--line);font-size:14px;color:var(--muted)}
.pane.after .pane-foot{color:var(--good);font-weight:500}

.compare-note{margin-top:26px;text-align:center;font-size:16px;color:var(--muted)}
.compare-note strong{color:var(--ink);font-weight:600}

/* ---------- sample prompt ---------------------------------------------- */

.prompt{
    background:var(--surface);border:1px solid var(--line-2);
    border-radius:var(--r-lg);overflow:hidden;
    box-shadow:0 3px 14px rgba(22,24,29,.05);
}
.prompt-head{
    display:flex;align-items:center;gap:12px;flex-wrap:wrap;
    padding:14px 20px;background:var(--paper-2);border-bottom:1px solid var(--line);
}
.prompt-label{font-size:13.5px;font-weight:600;color:var(--ink)}
.prompt-num{
    font-family:var(--mono);font-size:11.5px;font-weight:700;letter-spacing:.05em;
    background:var(--accent);color:#fff;border-radius:5px;padding:3px 8px;
}
.copy-btn{
    margin-left:auto;background:var(--surface);border:1px solid var(--line-2);
    color:var(--accent);font-family:var(--sans);font-size:13.5px;font-weight:600;
    padding:10px 16px;min-height:42px;border-radius:8px;cursor:pointer;transition:all .15s ease;
}
.copy-btn:hover{background:var(--accent-soft);border-color:var(--accent)}
.copy-btn:focus-visible{outline:3px solid var(--warm);outline-offset:2px}
.copy-btn.done{background:var(--good-soft);border-color:var(--good);color:var(--good)}

.prompt-body{
    padding:26px 24px;
    font-family:var(--mono);font-size:14px;line-height:1.75;color:var(--ink);
    white-space:pre-wrap;word-break:break-word;
}
.prompt-body b{color:var(--warm);font-weight:700}

.prompt-after{margin-top:22px;text-align:center;font-size:16px;color:var(--muted)}

/* ---------- chapters ---------------------------------------------------- */

.chapters{display:grid;gap:16px}
@media(min-width:760px){.chapters{grid-template-columns:1fr 1fr}}
@media(min-width:1000px){.chapters{grid-template-columns:repeat(3,1fr)}}

.chapter{
    background:var(--surface);border:1px solid var(--line);border-radius:var(--r-lg);
    padding:26px 24px;display:flex;flex-direction:column;
}
.chapter-n{
    font-family:var(--mono);font-size:11.5px;font-weight:700;letter-spacing:.08em;
    color:var(--muted);margin-bottom:10px;
}
.chapter h3{margin-bottom:8px}
.chapter > p{font-size:15px;margin-bottom:16px}
.chapter ul{list-style:none;margin-top:auto;display:grid;gap:7px;padding-top:16px;border-top:1px solid var(--line)}
.chapter li{display:flex;gap:9px;font-size:14.5px;color:var(--body);line-height:1.45}
.chapter li::before{content:"";width:5px;height:5px;border-radius:50%;background:var(--warm);flex:none;margin-top:8px}

/* ---------- audience ---------------------------------------------------- */

.audience{display:grid;gap:18px}
@media(min-width:820px){.audience{grid-template-columns:1fr 1fr;gap:22px}}
.aud{border-radius:var(--r-lg);padding:30px 28px;border:1px solid var(--line);background:var(--surface)}
.aud.yes{border-color:rgba(31,122,77,.3);background:var(--good-soft)}
.aud.no{border-color:rgba(168,67,58,.24);background:var(--bad-soft)}
.aud h3{margin-bottom:18px;font-size:21px}
.aud.yes h3{color:var(--good)}
.aud.no h3{color:var(--bad)}
.aud ul{list-style:none;display:grid;gap:12px}
.aud li{display:flex;gap:11px;font-size:15.5px;line-height:1.5;color:var(--ink)}
.aud li .mark{flex:none;font-weight:700;line-height:1.5}
.aud.yes .mark{color:var(--good)}
.aud.no .mark{color:var(--bad)}

/* ---------- offer ------------------------------------------------------- */

.offer{
    background:var(--surface);border:1px solid var(--line-2);border-radius:var(--r-lg);
    max-width:760px;margin:0 auto;overflow:hidden;
    box-shadow:0 4px 24px rgba(22,24,29,.06);
}
.offer-body{padding:clamp(30px,4vw,44px)}
.offer h2{font-size:clamp(25px,3.2vw,33px);margin-bottom:8px}
.offer-sub{font-size:16px;color:var(--muted);margin-bottom:26px}

.includes{list-style:none;display:grid;gap:13px;margin-bottom:30px}
.includes li{display:flex;gap:12px;font-size:16px;line-height:1.5;color:var(--ink)}
.includes li::before{
    content:"✓";flex:none;color:var(--good);font-weight:700;
    background:var(--good-soft);border-radius:50%;
    width:22px;height:22px;display:grid;place-items:center;font-size:12.5px;margin-top:2px;
}
.includes li span{color:var(--muted);font-size:15px}

.offer-price{
    display:flex;align-items:baseline;gap:12px;flex-wrap:wrap;
    padding-top:26px;border-top:1px solid var(--line);margin-bottom:22px;
}
.offer-price .n{font-family:var(--serif);font-size:44px;font-weight:600;color:var(--ink);line-height:1}
.offer-price .t{font-size:15px;color:var(--muted)}

.offer-cta{text-align:center}

.offer-foot{
    background:var(--paper-2);border-top:1px solid var(--line);
    padding:20px 28px;font-size:14.5px;color:var(--muted);text-align:center;
}

/* ---------- faq --------------------------------------------------------- */

.faq{max-width:760px;margin:0 auto;border-top:1px solid var(--line)}
.faq-item{border-bottom:1px solid var(--line)}
.faq-q{
    width:100%;display:flex;align-items:flex-start;justify-content:space-between;gap:18px;
    background:none;border:0;cursor:pointer;text-align:left;
    padding:22px 2px;
    font-family:var(--sans);font-size:17px;font-weight:600;color:var(--ink);line-height:1.4;
}
.faq-q:hover{color:var(--accent)}
.faq-q:focus-visible{outline:3px solid var(--warm);outline-offset:-3px;border-radius:4px}
.faq-q .plus{flex:none;font-size:22px;font-weight:400;color:var(--accent);line-height:1;transition:transform .2s ease}
.faq-item.open .plus{transform:rotate(45deg)}
.faq-a{max-height:0;overflow:hidden;transition:max-height .26s ease}
.faq-a p{padding:0 2px 24px;font-size:16px;color:var(--body);max-width:660px}

/* ---------- honest note ------------------------------------------------- */

.note{
    max-width:760px;margin:0 auto;text-align:center;
    background:var(--warm-soft);border:1px solid rgba(180,100,42,.24);
    border-radius:var(--r-lg);padding:clamp(30px,4vw,44px);
}
.note h2{font-size:clamp(23px,2.9vw,30px);margin-bottom:16px}
.note p{font-size:16.5px;max-width:620px;margin:0 auto 14px}
.note p:last-child{margin-bottom:0}
.note strong{color:var(--ink)}

/* ---------- final cta --------------------------------------------------- */

.final{
    background:linear-gradient(160deg,#1B3A5B 0%,#122A44 100%);
    border-radius:var(--r-lg);text-align:center;
    padding:clamp(40px,5.5vw,64px) clamp(24px,4vw,48px);
    color:#C6D5E4;
}
.final h2{color:#fff;margin-bottom:14px}
.final h2 em{color:#EBBE7E}
.final > p{font-size:17px;max-width:520px;margin:0 auto 28px}
.final .btn{background:#EBBE7E;color:#12283F;box-shadow:0 6px 20px rgba(0,0,0,.28)}
.final .btn:hover{background:#F2CE96;color:#12283F}
.final .trust{justify-content:center;color:#8FA6BD;margin-top:20px}
.final .trust .sep{color:rgba(255,255,255,.22)}
.final-price{font-family:var(--serif);font-size:20px;color:#EBBE7E;margin-bottom:22px}

/* ---------- footer ------------------------------------------------------ */

footer{border-top:1px solid var(--line);padding:44px 0 108px;background:var(--paper-2)}
@media(min-width:921px){footer{padding-bottom:44px}}
.foot-row{display:grid;gap:22px}
@media(min-width:760px){.foot-row{grid-template-columns:1.6fr 1fr;align-items:start;gap:40px}}
.foot-note{margin-top:12px;font-size:13.5px;color:var(--muted);max-width:520px;line-height:1.6}
.foot-copy{font-size:13.5px;color:var(--muted)}
@media(min-width:760px){.foot-copy{text-align:right}}

/* ---------- sticky mobile buy bar --------------------------------------- */

.sticky-buy{
    position:fixed;left:0;right:0;bottom:0;z-index:70;
    display:flex;align-items:center;gap:14px;
    padding:11px 16px calc(11px + env(safe-area-inset-bottom));
    background:rgba(255,255,255,.97);border-top:1px solid var(--line-2);
    box-shadow:0 -4px 20px rgba(22,24,29,.09);
    transform:translateY(105%);transition:transform .24s ease;
}
.sticky-buy.visible{transform:translateY(0)}
.sticky-buy .sb-price{font-family:var(--serif);font-size:23px;font-weight:600;color:var(--ink);line-height:1}
.sticky-buy .sb-sub{display:block;font-family:var(--sans);font-size:11.5px;font-weight:400;color:var(--muted);margin-top:3px}
.sticky-buy .btn{flex:1;padding:13px 18px;font-size:15.5px}
@media(min-width:921px){.sticky-buy{display:none}}

/* ---------- motion ------------------------------------------------------ */

/* Scoped to html.js so the page is never left invisible if app.js fails to
   load or is blocked — without JS, .reveal simply renders as normal content. */
.js .reveal{opacity:0;transform:translateY(14px);transition:opacity .5s ease,transform .5s ease}
.js .reveal.in{opacity:1;transform:none}

@media(prefers-reduced-motion:reduce){
    html{scroll-behavior:auto}
    *,*::before,*::after{animation-duration:.01ms!important;transition-duration:.01ms!important}
    .js .reveal{opacity:1;transform:none}
}

/* accessibility ---------------------------------------------------------- */

.skip{
    position:absolute;left:-9999px;top:0;z-index:100;
    background:var(--accent);color:#fff;padding:12px 20px;border-radius:0 0 8px 0;
}
.skip:focus{left:0}