/* ===== CHALKLINE · maths · chalkboard hero + graph-paper body ===== */
:root{--board:#14352B;--board-2:#0E2820;--chalk:#F4EFE2;--chalk-dim:#B9C4B4;
--paper:#FBFAF4;--grid:#E8E4D2;--ink:#22301F;--muted:#6E7A66;
--yellow:#F2C64B;--red:#E2604A;--blue:#3E7CB1;--wa:#25D366;
--d:'Fraunces',serif;--m:'JetBrains Mono',monospace;--b:'Inter',sans-serif;
--ease:cubic-bezier(.22,1,.36,1)}
*{margin:0;padding:0;box-sizing:border-box}
body{font-family:var(--b);color:var(--ink);line-height:1.65;font-size:16.5px;-webkit-font-smoothing:antialiased;overflow-x:hidden;
background:var(--paper);
background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);
background-size:34px 34px}
a{text-decoration:none;color:inherit}
h1,h2,h3{font-family:var(--d);line-height:1.1;letter-spacing:-.01em}
.wrap{max-width:960px;margin:0 auto;padding:0 20px}
section{padding:clamp(56px,9vw,96px) 0}
.rv{opacity:0;transform:translateY(24px);transition:.7s var(--ease)}
.rv.in{opacity:1;transform:none}
@media(prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important}.rv{opacity:1;transform:none}}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:9px;font-weight:650;font-size:.92rem;padding:15px 28px;border-radius:12px;min-height:52px;transition:.3s var(--ease)}
.btn:active{transform:scale(.97)}
.btn-y{background:var(--yellow);color:#332800;box-shadow:0 12px 30px -12px rgba(242,198,75,.7)}
.btn-y:hover{transform:translateY(-3px)}
.btn-ch{border:1.5px dashed var(--chalk-dim);color:var(--chalk)}
.btn-ch:hover{border-color:var(--yellow);color:var(--yellow)}
.btn-ink{background:var(--ink);color:var(--chalk)}
.btn-wa{background:var(--wa);color:#fff}
.k{font-family:var(--m);font-size:.72rem;font-weight:700;letter-spacing:.14em;text-transform:uppercase;color:var(--blue);display:block;margin-bottom:12px}
.k::before{content:"∴ "}
h2{font-size:clamp(1.7rem,5vw,2.5rem)}
h2 .u{position:relative;white-space:nowrap}
h2 .u svg{position:absolute;left:-2%;right:-2%;bottom:-.28em;width:104%;height:.5em}
h2 .u path{stroke:var(--red);stroke-width:3.5;fill:none;stroke-linecap:round;stroke-dasharray:300;stroke-dashoffset:300;transition:stroke-dashoffset 1.4s var(--ease) .3s}
.in h2 .u path,.rv.in .u path{stroke-dashoffset:0}
.lead{color:var(--muted);max-width:56ch;margin-top:12px}

/* HERO — chalkboard */
.hero{background:radial-gradient(900px 500px at 70% -10%,#1C4437,transparent 65%),var(--board);color:var(--chalk);position:relative;overflow:hidden;border-bottom:10px solid #8A5A33}
.hero::after{content:"";position:absolute;inset:0;pointer-events:none;opacity:.35;
background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.8'/%3E%3CfeColorMatrix values='0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 .05 0'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E")}
.hero .doodle{position:absolute;font-family:var(--m);color:var(--chalk-dim);opacity:.4;user-select:none;font-size:.95rem}
.d1{top:14%;right:8%;transform:rotate(6deg)}
.d2{bottom:20%;left:5%;transform:rotate(-5deg)}
.d3{top:44%;right:16%;transform:rotate(-3deg);font-size:1.5rem;color:var(--yellow);opacity:.55}
.hero-nav{display:flex;justify-content:space-between;align-items:center;padding:20px;max-width:960px;margin:0 auto;position:relative;z-index:2}
.mark{font-family:var(--m);font-weight:700;font-size:.95rem}
.mark i{font-style:normal;color:var(--yellow)}
.hero-body{position:relative;z-index:2;padding:clamp(48px,9vw,90px) 0 clamp(56px,9vw,90px)}
.stamp{font-family:var(--m);font-size:.74rem;letter-spacing:.14em;text-transform:uppercase;color:var(--yellow);display:block;margin-bottom:20px}
.hero h1{font-size:clamp(2.5rem,9.5vw,5rem);color:var(--chalk);max-width:15ch}
.hero h1 em{font-style:italic;font-weight:450;color:var(--yellow)}
.hero .sub{color:var(--chalk-dim);max-width:52ch;margin:22px 0 32px;font-size:1.04rem}
.hero-ctas{display:flex;gap:12px;flex-wrap:wrap;margin-bottom:26px}
.hero-meta{font-family:var(--m);font-size:.76rem;color:var(--chalk-dim);display:flex;gap:20px;flex-wrap:wrap}
.hero-meta b{color:var(--chalk)}

/* equation marquee */
.eqband{background:var(--ink);color:var(--paper);overflow:hidden;padding:13px 0}
.eq-track{display:flex;gap:42px;width:max-content;animation:mq 24s linear infinite;font-family:var(--m);font-size:.92rem}
.eq-track b{color:var(--yellow)}
@keyframes mq{to{transform:translateX(-50%)}}

/* proof stats */
.proofs{display:grid;grid-template-columns:repeat(2,1fr);gap:14px;margin-top:34px}
.proof{background:#fff;border:1.5px solid var(--ink);border-radius:4px;padding:24px 20px;position:relative;box-shadow:5px 5px 0 var(--grid);transition:.35s var(--ease)}
.proof:hover{transform:translate(-3px,-3px);box-shadow:8px 8px 0 var(--yellow)}
.proof::before{content:attr(data-q);position:absolute;top:-11px;left:14px;background:var(--paper);padding:0 8px;font-family:var(--m);font-size:.68rem;color:var(--blue);font-weight:700}
.proof b{font-family:var(--m);font-weight:700;font-size:clamp(1.7rem,5vw,2.3rem);display:block}
.proof span{font-size:.82rem;color:var(--muted)}
.proof .qed{position:absolute;bottom:12px;right:14px;font-family:var(--m);font-size:.64rem;color:var(--red);font-weight:700}

/* subjects — set notation */
.setrow{font-family:var(--m);font-size:.98rem;margin-top:30px;line-height:2.4}
.setrow .brace{color:var(--red);font-size:1.3rem;font-weight:700}
.setrow i{font-style:normal;background:#fff;border:1.5px solid var(--ink);border-radius:999px;padding:8px 16px;margin:0 4px;font-size:.84rem;font-weight:650;display:inline-block;transition:.25s var(--ease)}
.setrow i:hover{background:var(--yellow);transform:rotate(-1.5deg)}
.setrow i small{color:var(--muted);font-weight:500}

/* timeline — number line */
.nline{position:relative;margin-top:44px;padding-left:34px}
.nline::before{content:"";position:absolute;left:10px;top:6px;bottom:6px;width:2px;background:var(--ink)}
.nl-item{position:relative;padding-bottom:38px}
.nl-item::before{content:"";position:absolute;left:-30px;top:8px;width:14px;height:2px;background:var(--ink)}
.nl-item::after{content:attr(data-x);position:absolute;left:-58px;top:0;font-family:var(--m);font-size:.7rem;color:var(--red);font-weight:700;width:22px;text-align:right}
.nl-item .yr{font-family:var(--m);font-size:.72rem;color:var(--blue);font-weight:700}
.nl-item h3{font-size:1.2rem;margin:4px 0 2px}
.nl-item .org{font-weight:650;font-size:.85rem;color:var(--muted);margin-bottom:6px}
.nl-item p{color:var(--muted);font-size:.92rem;max-width:56ch}

/* awards — theorem boxes */
.thm{background:#fff;border-left:4px solid var(--yellow);border-top:1.5px solid var(--grid);border-right:1.5px solid var(--grid);border-bottom:1.5px solid var(--grid);border-radius:0 8px 8px 0;padding:18px 20px;margin-bottom:12px;display:flex;justify-content:space-between;gap:14px;flex-wrap:wrap}
.thm b{font-family:var(--d);font-size:1.02rem;display:block}
.thm b::before{content:"Theorem. ";font-style:italic;color:var(--red);font-weight:450}
.thm span{font-size:.82rem;color:var(--muted)}
.thm .yr{font-family:var(--m);color:var(--blue);font-weight:700;font-size:.78rem;align-self:center}

/* testimonials — margin notes */
.note{background:#FFFDF2;border:1.5px solid var(--grid);border-radius:10px;padding:20px 22px;margin-bottom:12px;position:relative;transform:rotate(-.4deg)}
.note:nth-child(even){transform:rotate(.5deg);background:#F4F8FF}
.note::before{content:"✎";position:absolute;top:-12px;right:16px;background:var(--yellow);width:26px;height:26px;border-radius:50%;display:grid;place-items:center;font-size:.85rem}
.note p{font-family:var(--d);font-style:italic;font-size:1rem;margin-bottom:8px}
.note b{font-size:.84rem}.note span{display:block;font-size:.75rem;color:var(--muted)}

/* job prefs — worked solution */
.soln{background:var(--board);color:var(--chalk);border-radius:16px;padding:clamp(28px,5vw,44px);margin-top:34px;border-bottom:8px solid #8A5A33}
.soln h3{font-family:var(--m);font-size:.78rem;letter-spacing:.14em;text-transform:uppercase;color:var(--yellow);margin-bottom:18px}
.soln h3::before{content:"Q. "}
.srow{display:flex;justify-content:space-between;gap:14px;padding:13px 0;border-bottom:1px dashed rgba(244,239,226,.25);font-size:.92rem;flex-wrap:wrap}
.srow span{color:var(--chalk-dim);font-family:var(--m);font-size:.8rem}
.srow b{text-align:right}
.srow .yes{color:var(--yellow)}
.soln .ans{margin-top:18px;font-family:var(--m);font-size:.8rem;color:var(--yellow)}
.refs{display:grid;gap:10px;margin-top:16px}
.ref{border:1px dashed rgba(244,239,226,.3);border-radius:10px;padding:14px 18px;font-size:.86rem}
.ref b{font-family:var(--d)}.ref span{display:block;color:var(--chalk-dim);font-size:.76rem}

/* finale */
.fin{text-align:center}
.fin .big-eq{font-family:var(--m);color:var(--blue);font-size:.85rem;margin-bottom:16px}
.fin p{color:var(--muted);margin-top:10px}
.fin .ctas{display:flex;gap:12px;justify-content:center;flex-wrap:wrap;margin-top:28px}
footer{border-top:1.5px solid var(--grid);padding:20px;text-align:center;font-size:.75rem;color:var(--muted)}
footer a{color:var(--blue);font-weight:650}
.stick{position:fixed;left:0;right:0;bottom:0;z-index:40;background:rgba(251,250,244,.95);backdrop-filter:blur(12px);border-top:1.5px solid var(--ink);padding:10px 16px calc(10px + env(safe-area-inset-bottom));display:flex;gap:10px;transform:translateY(110%);transition:.4s var(--ease)}
.stick.show{transform:none}
.stick .btn{flex:1;min-height:48px}
@media(min-width:800px){
 .proofs{grid-template-columns:repeat(4,1fr)}
 .notes-grid{display:grid;grid-template-columns:1fr 1fr 1fr;gap:14px}.note{margin-bottom:0}
 .refs{grid-template-columns:1fr 1fr}
 .stick{display:none}
}
.contact-form-wrap{margin-top:22px;max-width:520px;margin-left:auto;margin-right:auto}
.contact-form .form_group{margin-bottom:12px}
.contact-form input,.contact-form textarea{width:100%;padding:12px 14px;border-radius:10px;border:1px solid rgba(0,0,0,.12);font:inherit;background:#fff}
.contact-form textarea{min-height:110px;resize:vertical}
.text-danger{color:#c0392b;font-size:.8rem;margin-top:4px}