:root{
  --bg:#f4f5fb; --card:#ffffff; --ink:#1f2233; --muted:#6b7091; --line:#e6e8f2;
  --primary:#5b57e0; --primary-d:#4844c4; --primary-soft:#edecfd;
  --ok:#16a34a; --ok-soft:#e7f6ec; --bad:#dc2626; --bad-soft:#fdecec;
  --amber:#e0913a; --r:16px; --r-sm:11px;
  --shadow:0 1px 2px rgba(31,34,51,.04),0 10px 30px -16px rgba(31,34,51,.25);
}
*{margin:0;padding:0;box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Inter,sans-serif;
  background:var(--bg);color:var(--ink);line-height:1.55;-webkit-font-smoothing:antialiased;
  padding-bottom:env(safe-area-inset-bottom);overflow-wrap:break-word;touch-action:manipulation}
a{color:inherit;text-decoration:none}
.wrap{width:100%;max-width:680px;margin:0 auto;padding:0 1.1rem}

/* top bar */
.top{position:sticky;top:0;z-index:20;background:rgba(244,245,251,.9);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.top-in{max-width:680px;margin:0 auto;padding:.7rem 1.1rem;display:flex;align-items:center;justify-content:space-between}
.brand{display:flex;align-items:center;gap:.5rem;font-weight:800;letter-spacing:-.01em}
.brand .dot{width:30px;height:30px;border-radius:9px;background:linear-gradient(135deg,var(--primary),#8b5cf6);color:#fff;display:grid;place-items:center;font-size:1rem}
.brand small{display:block;font-size:.62rem;font-weight:600;color:var(--muted);letter-spacing:.08em;text-transform:uppercase}
.top-user{display:flex;align-items:center;gap:.7rem;font-size:.85rem;color:var(--muted)}
.avatar{width:30px;height:30px;border-radius:50%;background:var(--primary-soft);color:var(--primary-d);display:grid;place-items:center;font-weight:700;font-size:.85rem}

.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r);box-shadow:var(--shadow)}
.pad{padding:1.3rem}
h1{font-size:1.55rem;letter-spacing:-.02em;margin-bottom:.3rem}
h2{font-size:1.05rem;margin-bottom:.8rem}
.muted{color:var(--muted)}
.section{margin:1.4rem 0}
.label{font-size:.72rem;font-weight:700;letter-spacing:.09em;text-transform:uppercase;color:var(--muted);margin-bottom:.6rem}

/* buttons / pills */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:.5rem;font:inherit;font-weight:700;
  padding:.9rem 1.3rem;border-radius:999px;border:1px solid transparent;cursor:pointer;transition:transform .12s,box-shadow .15s,background .15s;width:100%}
.btn:active{transform:scale(.98)}
.btn-primary{background:var(--primary);color:#fff;box-shadow:0 10px 22px -12px var(--primary)}

.btn-ghost{background:#fff;border-color:var(--line);color:var(--ink)}

.btn:disabled{opacity:.45;cursor:not-allowed;box-shadow:none}
.btn:disabled:hover{background:var(--primary)}

/* choice grids */
.grid{display:grid;gap:.6rem;grid-template-columns:minmax(0,1fr)}
.grid-2{grid-template-columns:repeat(2,minmax(0,1fr))}
.grid-3{grid-template-columns:repeat(3,minmax(0,1fr))}
.grid-4{grid-template-columns:repeat(4,minmax(0,1fr))}
.opt{display:flex;align-items:center;gap:.7rem;padding:.7rem .9rem;border:1.5px solid var(--line);border-radius:var(--r-sm);
  background:#fff;cursor:pointer;transition:border-color .12s,background .12s;text-align:left;font:inherit;width:100%}

.opt .k{flex-shrink:0;width:26px;height:26px;border-radius:7px;background:var(--primary-soft);color:var(--primary-d);
  display:grid;place-items:center;font-weight:700;font-size:.8rem}
.opt.sel{border-color:var(--primary);background:var(--primary-soft)}
.opt.sel .k{background:var(--primary);color:#fff}
.opt.correct{border-color:var(--ok);background:var(--ok-soft)}
.opt.correct .k{background:var(--ok);color:#fff}
.opt.wrong{border-color:var(--bad);background:var(--bad-soft)}
.opt.wrong .k{background:var(--bad);color:#fff}
.opt[disabled]{cursor:default}
.opt{min-width:0}
.opt span:not(.k){min-width:0;overflow-wrap:anywhere;font-size:calc(1rem * var(--zoom,1))}
.stem,.read-body{overflow-wrap:anywhere}
.card{min-width:0;overflow-wrap:anywhere}

.pick{padding:1.15rem .6rem;border:1.5px solid var(--line);border-radius:var(--r-sm);background:#fff;cursor:pointer;
  text-align:center;font:inherit;font-weight:800;font-size:1.3rem;transition:all .12s}
.pick.sel{border-color:var(--primary);background:var(--primary-soft);color:var(--primary-d)}
.pick small{display:block;font-size:.65rem;font-weight:600;letter-spacing:.06em;text-transform:uppercase;color:var(--muted);margin-top:.2rem}
.pick.sel small{color:var(--primary-d)}

.mode{display:flex;gap:.75rem;align-items:flex-start;padding:.9rem 1rem;border:1.5px solid var(--line);border-radius:var(--r-sm);background:#fff;cursor:pointer;text-align:left;width:100%;font:inherit;transition:all .12s}
.mode.sel{border-color:var(--primary);background:var(--primary-soft)}
.mode .em{font-size:1.3rem;line-height:1.2}
.mode b{display:block;font-size:.95rem}
.mode span{font-size:.8rem;color:var(--muted)}

/* stats */
.statrow{display:grid;grid-template-columns:1fr 1fr 1fr;gap:.6rem;text-align:center}
.stat b{display:block;font-size:1.7rem;letter-spacing:-.02em}
.stat span{font-size:.72rem;color:var(--muted);text-transform:uppercase;letter-spacing:.06em}
.bar{height:9px;border-radius:999px;background:var(--line);overflow:hidden;margin-top:.4rem}
.bar>i{display:block;height:100%;background:linear-gradient(90deg,var(--primary),#8b5cf6)}
.chip{display:inline-block;font-size:.72rem;font-weight:700;padding:.2rem .6rem;border-radius:999px;background:var(--primary-soft);color:var(--primary-d)}

/* quiz progress */
.qbar{height:6px;background:var(--line);border-radius:999px;overflow:hidden;margin:.2rem 0 1rem}
.qbar>i{display:block;height:100%;background:var(--primary);transition:width .3s}
.qmeta{display:flex;justify-content:space-between;font-size:.8rem;color:var(--muted);margin-bottom:.2rem}
.stem{font-size:calc(1.18rem * var(--zoom,1));font-weight:600;line-height:1.4;margin:.5rem 0 1.1rem}
.feedback{margin-top:1rem;padding:.85rem 1rem;border-radius:var(--r-sm);font-size:.9rem;font-weight:600;display:none}
.feedback.show{display:block}
.feedback.good{background:var(--ok-soft);color:#15803d}
.feedback.no{background:var(--bad-soft);color:#b91c1c}
.feedback .src{display:block;font-weight:500;color:var(--muted);font-size:.78rem;margin-top:.3rem}

input[type=email],input[type=password],input[type=text]{width:100%;padding:.85rem 1rem;border:1.5px solid var(--line);border-radius:var(--r-sm);font:inherit;background:#fff;display:block}
input:focus{outline:none;border-color:var(--primary)}
.sel-input{width:100%;padding:.85rem 1rem;border:1.5px solid var(--line);border-radius:var(--r-sm);font:inherit;background:#fff;color:var(--ink);
  appearance:none;-webkit-appearance:none;cursor:pointer;
  background-image:url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='14' height='14' viewBox='0 0 24 24' fill='none' stroke='%236b7091' stroke-width='2'><path d='M6 9l6 6 6-6'/></svg>");
  background-repeat:no-repeat;background-position:right 1rem center}
.sel-input:focus{outline:none;border-color:var(--primary)}
.err{background:var(--bad-soft);color:#b91c1c;padding:.7rem 1rem;border-radius:var(--r-sm);font-size:.88rem;font-weight:600}
.linkbtn{background:none;border:none;color:var(--muted);font:inherit;font-size:.85rem;cursor:pointer;padding:.25rem .3rem;text-decoration:none}
.zoomctl{display:inline-flex;align-items:center;gap:.25rem;border:1px solid var(--line);border-radius:999px;padding:.15rem .25rem;background:#fff;flex-shrink:0}
.zoomctl button{border:none;background:none;font:inherit;font-weight:800;cursor:pointer;color:var(--primary-d);width:30px;height:30px;border-radius:50%;line-height:1;padding:0}
.zoomctl button:active{background:var(--primary-soft)}
.zoomctl .zl{font-size:.68rem;color:var(--muted);font-weight:700;letter-spacing:.03em;padding:0 .1rem}
.read-label{font-size:.72rem;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:var(--primary-d)}
.read h2{font-size:calc(1.2rem * var(--zoom,1))}
.read-body p{margin:.5rem 0;font-size:calc(.97rem * var(--zoom,1));line-height:1.6}
.read-body ul,.read-body ol{margin:.4rem 0 0;padding-left:1.2rem}
.read-body li{margin:.5rem 0;font-size:calc(.96rem * var(--zoom,1));line-height:1.55}
.read-body li::marker{color:var(--primary)}
.read-body h3{font-size:calc(1.14rem * var(--zoom,1));margin:1.2rem 0 .35rem;letter-spacing:-.01em}
.read-body h4{font-size:calc(1.02rem * var(--zoom,1));margin:.95rem 0 .3rem}
.read-body h5{font-size:calc(.95rem * var(--zoom,1));margin:.8rem 0 .25rem;color:var(--muted)}
.rd-note{background:var(--primary-soft);border-radius:12px;padding:.75rem .95rem;margin:.9rem 0;font-size:calc(.92rem * var(--zoom,1))}
.rd-note b{display:block;margin-bottom:.25rem;color:var(--primary-d)}
.rd-fig{font-size:calc(.85rem * var(--zoom,1));color:var(--muted);font-style:italic}
.rd-tablewrap{overflow-x:auto;margin:.8rem 0}
.rd-table{border-collapse:collapse;width:100%;font-size:calc(.85rem * var(--zoom,1))}
.rd-table td{border:1px solid var(--line);padding:.35rem .5rem;vertical-align:top}
/* tabs */
.tabs{display:flex;gap:.3rem;margin:.1rem 0 1rem;border-bottom:1px solid var(--line)}
.tab{border:none;background:none;font:inherit;font-weight:700;font-size:.92rem;color:var(--muted);cursor:pointer;padding:.55rem .6rem;border-bottom:2.5px solid transparent;margin-bottom:-1px}
.tab.sel{color:var(--primary-d);border-bottom-color:var(--primary)}

/* ============================================================
   Landing (.lp) + auth pages + courtesy footer
   ============================================================ */
.brand-logo{display:block;border-radius:9px}

/* subtle background art */
.lp-bg{position:fixed;inset:0;width:100%;height:100%;z-index:0;opacity:.55;pointer-events:none}
.lp-nav,.lp-hero,.lp-strip,.lp-section,.courtesy{position:relative;z-index:1}

/* landing nav */
.lp-nav{max-width:1040px;margin:0 auto;padding:1.1rem 1.3rem;display:flex;align-items:center;justify-content:space-between}
.lp-nav .brand{font-size:1.15rem}
.lp-signin{font-weight:700;font-size:.9rem;color:var(--primary-d);padding:.5rem .95rem;border-radius:999px}


/* hero */
.lp-hero{max-width:1040px;margin:0 auto;padding:1.2rem 1.3rem 2.5rem;display:grid;grid-template-columns:1fr;gap:2rem;align-items:center}
.lp-eyebrow{display:inline-block;font-size:.72rem;font-weight:800;letter-spacing:.09em;text-transform:uppercase;color:var(--primary-d);background:var(--primary-soft);padding:.35rem .8rem;border-radius:999px;margin-bottom:1rem}
.lp-hero h1{font-size:2.3rem;line-height:1.08;letter-spacing:-.03em;margin-bottom:.9rem}
.lp-sub{font-size:1.05rem;color:var(--muted);max-width:40ch}
.lp-sub b{color:var(--ink)}
.lp-cta{display:flex;flex-wrap:wrap;gap:.7rem;margin-top:1.5rem}
.lp-cta .btn{width:auto;padding:.85rem 1.4rem}
.lp-note{font-size:.82rem;color:var(--muted);margin-top:.8rem}

/* hero mock card */
.lp-hero-card{display:flex;justify-content:center}
.lp-mock{width:100%;max-width:360px;transform:rotate(-1.4deg)}
.lp-mock-meta{display:flex;justify-content:space-between;align-items:center;font-size:.8rem;color:var(--muted);margin-bottom:.5rem}
.lp-mock-stem{font-weight:600;font-size:1rem;margin:.3rem 0 .9rem;line-height:1.4}
.lp-mock-opt{padding:.65rem .85rem;border:1.5px solid var(--line);border-radius:var(--r-sm);margin-bottom:.5rem;font-size:.9rem}
.lp-mock-opt.sel{border-color:var(--primary);background:var(--primary-soft);color:var(--primary-d);font-weight:600}

/* stat strip */
.lp-strip{max-width:1040px;margin:0 auto;padding:0 1.3rem;display:grid;grid-template-columns:repeat(3,1fr);gap:1rem;text-align:center}
.lp-strip>div{background:var(--card);border:1px solid var(--line);border-radius:var(--r);padding:1.1rem .5rem;box-shadow:var(--shadow)}
.lp-strip b{display:block;font-size:1.8rem;letter-spacing:-.02em;color:var(--primary-d)}
.lp-strip span{font-size:.72rem;color:var(--muted);text-transform:uppercase;letter-spacing:.06em}

/* content sections */
.lp-section{max-width:1040px;margin:0 auto;padding:3rem 1.3rem 0}
.lp-head{text-align:center;max-width:46ch;margin:0 auto 1.8rem}
.lp-head h2{font-size:1.6rem;letter-spacing:-.02em;margin-bottom:.4rem}

/* features */
.lp-features{display:grid;grid-template-columns:repeat(2,1fr);gap:1rem}
.lp-feat{background:var(--card);border:1px solid var(--line);border-radius:var(--r);padding:1.3rem;box-shadow:var(--shadow)}
.lp-ic{display:grid;place-items:center;width:44px;height:44px;border-radius:12px;background:var(--primary-soft);font-size:1.4rem;margin-bottom:.7rem}
.lp-feat b{display:block;font-size:1.02rem;margin-bottom:.25rem}
.lp-feat p{font-size:.88rem;color:var(--muted);line-height:1.5}

/* steps */
.lp-steps{list-style:none;display:grid;grid-template-columns:repeat(3,1fr);gap:1rem}
.lp-steps li{display:flex;gap:.8rem;align-items:flex-start;background:var(--card);border:1px solid var(--line);border-radius:var(--r);padding:1.2rem;box-shadow:var(--shadow)}
.lp-num{flex-shrink:0;width:32px;height:32px;border-radius:50%;background:linear-gradient(135deg,var(--primary),#8b5cf6);color:#fff;display:grid;place-items:center;font-weight:800}
.lp-steps b{display:block;margin-bottom:.15rem}
.lp-steps p{font-size:.85rem;color:var(--muted)}
.lp-cta-center{justify-content:center;margin-top:1.8rem}

/* courtesy footer — CodeWorks logo on a dark branded card */
.courtesy{max-width:1040px;margin:3rem auto 0;padding:2rem 1.3rem 2.8rem}
.courtesy-card{max-width:440px;margin:0 auto;background:linear-gradient(135deg,#5b57e0,#8b5cf6);border-radius:18px;padding:1.8rem 1.4rem;text-align:center;
  box-shadow:0 18px 40px -18px rgba(91,87,224,.65)}
.courtesy-logo{width:230px;max-width:78%;height:auto;display:block;margin:0 auto .8rem;filter:drop-shadow(0 2px 6px rgba(20,23,38,.18))}
.courtesy-card p{font-size:.85rem;color:rgba(255,255,255,.82);margin-top:.35rem}
.courtesy-card a{color:#fff;font-weight:700}
.courtesy-contact{display:flex;gap:.6rem;justify-content:center;align-items:center;margin-top:.55rem!important}
.courtesy-contact span{color:rgba(255,255,255,.45)}

/* auth pages (login / register / verify / resend) */
.auth{min-height:100vh;display:flex;flex-direction:column}
.auth-box{flex:1;width:100%;max-width:420px;margin:0 auto;padding:2.2rem 1.2rem 1rem;display:flex;flex-direction:column;align-items:center}
.auth-brand{font-size:1.3rem;margin-bottom:1.4rem}
.auth-card{width:100%}
.auth-card h1{font-size:1.5rem}
.auth-sent{text-align:center}
.auth-emoji{font-size:2.6rem;margin-bottom:.4rem;line-height:1}
.auth-alt{margin-top:1.1rem;font-size:.9rem;color:var(--muted)}
.auth-alt a{color:var(--primary-d);font-weight:700}

@media(min-width:780px){
  .lp-hero{grid-template-columns:1.1fr .9fr;padding-top:2.4rem;padding-bottom:3.5rem}
  .lp-hero h1{font-size:2.9rem}
}
@media(max-width:560px){
  .lp-features{grid-template-columns:1fr}
  .lp-steps{grid-template-columns:1fr}
  .lp-strip b{font-size:1.5rem}
  .lp-hero h1{font-size:2rem}
}

/* ============================================================
   Auth bottom-sheet modal (slide up + bounce)
   ============================================================ */
.sheet-overlay{position:fixed;inset:0;z-index:200;background:rgba(20,23,38,.5);-webkit-backdrop-filter:blur(3px);backdrop-filter:blur(3px);
  display:flex;align-items:flex-end;justify-content:center;opacity:0;transition:opacity .25s ease;pointer-events:none}
.sheet-overlay.open{opacity:1;pointer-events:auto}
.sheet{position:relative;width:100%;max-width:460px;background:var(--card);border-radius:24px 24px 0 0;
  padding:.8rem 1.4rem calc(1.8rem + env(safe-area-inset-bottom));box-shadow:0 -12px 44px rgba(20,23,38,.28);
  max-height:94vh;overflow-y:auto;transform:translateY(102%);
  transition:transform .46s cubic-bezier(.18,.89,.32,1.4)}
.sheet-overlay.open .sheet{transform:translateY(0)}
@media(prefers-reduced-motion:reduce){.sheet{transition:transform .2s ease}}
.sheet-grip{width:42px;height:4px;border-radius:99px;background:var(--line);margin:.2rem auto .4rem}
.sheet-close{position:absolute;top:.7rem;right:1rem;border:none;background:none;font-size:1.7rem;line-height:1;color:var(--muted);cursor:pointer;padding:.2rem .4rem}
.sheet-brand{text-align:center;margin:.2rem 0 .6rem}
.sheet-brand img{border-radius:11px;display:inline-block}
.sheet .auth-view h2{font-size:1.4rem;text-align:center;margin-bottom:.2rem}
.sheet .auth-view>.muted{text-align:center}
.sheet form{display:grid;gap:.8rem;margin-top:1.1rem}
.sheet-msg{margin-top:1rem;padding:.7rem 1rem;border-radius:var(--r-sm);font-size:.88rem;font-weight:600}
.sheet-msg.err{background:var(--bad-soft);color:#b91c1c}
.sheet-msg.info{background:var(--primary-soft);color:var(--primary-d)}
.sheet-switch{text-align:center;margin-top:1.1rem;font-size:.9rem;color:var(--muted)}
.sheet-switch a{color:var(--primary-d);font-weight:700;cursor:pointer}
.sheet .auth-sent{text-align:center;padding:.6rem 0 .4rem}
@media(min-width:560px){ .sheet-overlay{align-items:center} .sheet{border-radius:24px;margin:1rem} }

/* prominent top-bar nav pills (Learn / Stats) */
.top-user .nav-link{display:inline-flex;align-items:center;gap:.3rem;font-weight:700;font-size:.85rem;color:var(--primary-d);
  background:var(--primary-soft);padding:.42rem .8rem;border-radius:999px;transition:background .12s,color .12s}


/* prominent "End quiz" control */
.btn-end{display:inline-flex;align-items:center;gap:.35rem;font:inherit;font-weight:700;font-size:.82rem;color:var(--muted);
  background:#fff;border:1.5px solid var(--line);border-radius:999px;padding:.42rem .9rem;cursor:pointer;transition:all .12s}
.btn-end:active{border-color:var(--bad);color:var(--bad);background:var(--bad-soft)}

/* stylized confirm modal (replaces native confirm) */
.modal-overlay{position:fixed;inset:0;z-index:300;background:rgba(20,23,38,.5);-webkit-backdrop-filter:blur(3px);backdrop-filter:blur(3px);
  display:flex;align-items:center;justify-content:center;padding:1.2rem;opacity:0;transition:opacity .18s ease;pointer-events:none}
.modal-overlay.open{opacity:1;pointer-events:auto}
.modal-box{width:100%;max-width:360px;background:var(--card);border-radius:18px;padding:1.5rem 1.4rem;text-align:center;
  box-shadow:0 24px 60px -20px rgba(20,23,38,.5);transform:translateY(10px) scale(.98);transition:transform .22s cubic-bezier(.18,.89,.32,1.35)}
.modal-overlay.open .modal-box{transform:none}
.modal-box h3{font-size:1.2rem;margin-bottom:.4rem}
.modal-box p{color:var(--muted);font-size:.92rem;margin-bottom:1.3rem}
.modal-actions{display:flex;gap:.6rem}
.modal-actions .btn{flex:1;padding:.8rem 1rem}
.btn-danger{background:var(--bad);color:#fff}


/* Lock In Answer: pre-select (dim) + in-flight (spinner) states */
.btn,.opt{touch-action:manipulation}
.btn.dim{opacity:.5}
.btn.loading{opacity:.92;pointer-events:none}
.btn.loading::before{content:"";width:15px;height:15px;border:2.5px solid rgba(255,255,255,.45);border-top-color:#fff;border-radius:50%;animation:mbspin .6s linear infinite}
@keyframes mbspin{to{transform:rotate(360deg)}}
@media (prefers-reduced-motion:reduce){.btn.loading::before{animation:none}}

/* hover effects only where a real pointer can hover — prevents iOS "tap twice" (sticky :hover) */
@media (hover:hover){
  .btn-primary:hover{background:var(--primary-d)}
  .btn-ghost:hover{border-color:var(--primary);color:var(--primary-d)}
  .btn-danger:hover{background:#b91c1c}
  .opt:hover{border-color:var(--primary)}
  .pick:hover{border-color:var(--primary);background:var(--primary-soft);color:var(--primary-d)}
  .mode:hover{border-color:var(--primary);background:var(--primary-soft)}
  .top-user .nav-link:hover{background:var(--primary);color:#fff}
  .btn-end:hover{border-color:var(--bad);color:var(--bad);background:var(--bad-soft)}
  .lp-signin:hover{background:var(--primary-soft)}
  .zoomctl button:hover{background:var(--primary-soft)}
  .linkbtn:hover{color:var(--bad)}
  .sheet-close:hover{color:var(--ink)}
}