/* ============================================================
   Internet Learners — shared stylesheet
   Palette: cool paper, ink navy, indigo, highlighter amber
   Type: Newsreader (display) / IBM Plex Sans (body) / IBM Plex Mono (labels)
   ============================================================ */

:root{
  --paper:#F6F5F1;
  --paper-raised:#FFFFFF;
  --ink:#1A2130;
  --ink-soft:#5A6478;
  --rule:#E1DED4;
  --indigo:#2F3E8F;
  --indigo-deep:#212C69;
  --highlighter:#F5C750;
  --highlighter-soft:#FBEBBE;
  --moss:#41705A;

  --measure:34rem;
  --gap:1.5rem;
}

*,*::before,*::after{box-sizing:border-box;}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;}
@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto;}
  *{animation-duration:.001ms !important;transition-duration:.001ms !important;}
}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:'IBM Plex Sans',system-ui,-apple-system,'Segoe UI',sans-serif;
  font-size:1.0625rem;
  line-height:1.68;
  -webkit-font-smoothing:antialiased;
}

/* ---------- Layout ---------- */
.shell{width:100%;max-width:46rem;margin:0 auto;padding:0 1.25rem;}
.shell-wide{width:100%;max-width:62rem;margin:0 auto;padding:0 1.25rem;}

/* Notebook margin rule on the article column */
.article{position:relative;}
@media(min-width:56rem){
  .article::before{
    content:"";position:absolute;left:-1.75rem;top:.4rem;bottom:.4rem;
    width:1px;background:var(--rule);
  }
}

/* ---------- Type ---------- */
h1,h2,h3,h4{
  font-family:'Newsreader',Georgia,'Times New Roman',serif;
  font-weight:600;line-height:1.18;color:var(--ink);
  margin:0 0 .5em;text-wrap:balance;
}
h1{font-size:clamp(2rem,5.6vw,3rem);letter-spacing:-.015em;}
h2{font-size:clamp(1.45rem,3.6vw,1.95rem);margin-top:2.4em;}
h3{font-size:1.2rem;margin-top:1.9em;font-weight:600;}
p{margin:0 0 1.15em;max-width:var(--measure);}
li{margin-bottom:.5em;}
ul,ol{max-width:var(--measure);padding-left:1.25rem;}
a{color:var(--indigo);text-decoration-thickness:1px;text-underline-offset:.16em;}
a:hover{color:var(--indigo-deep);}
strong{font-weight:600;}
:focus-visible{outline:3px solid var(--indigo);outline-offset:3px;border-radius:2px;}

.eyebrow{
  font-family:'IBM Plex Mono',ui-monospace,monospace;
  font-size:.72rem;letter-spacing:.14em;text-transform:uppercase;
  color:var(--ink-soft);margin:0 0 1rem;
}
.lede{
  font-size:1.2rem;line-height:1.55;color:var(--ink);
  max-width:36rem;margin-bottom:1.6em;
}

/* Signature: highlighter swipe */
.hl{
  background-image:linear-gradient(100deg,
    rgba(245,199,80,0) 0%, rgba(245,199,80,.75) 5%,
    rgba(245,199,80,.75) 95%, rgba(245,199,80,0) 100%);
  background-repeat:no-repeat;
  background-size:100% .62em;
  background-position:0 .72em;
  padding:0 .12em;
}

/* ---------- Header / nav ---------- */
.masthead{border-bottom:1px solid var(--rule);background:var(--paper);}
.masthead-in{
  display:flex;align-items:center;justify-content:space-between;
  gap:1rem;padding:.9rem 0;flex-wrap:wrap;
}
.wordmark{
  font-family:'Newsreader',serif;font-weight:600;font-size:1.15rem;
  color:var(--ink);text-decoration:none;letter-spacing:-.01em;
}
.wordmark span{color:var(--indigo);}
.nav{display:flex;gap:1.1rem;flex-wrap:wrap;}
.nav a{
  font-family:'IBM Plex Mono',monospace;font-size:.76rem;
  letter-spacing:.08em;text-transform:uppercase;
  color:var(--ink-soft);text-decoration:none;
}
.nav a:hover{color:var(--indigo);text-decoration:underline;}

/* ---------- Breadcrumb ---------- */
.crumbs{
  font-family:'IBM Plex Mono',monospace;font-size:.72rem;
  color:var(--ink-soft);padding:1.5rem 0 .25rem;
}
.crumbs a{color:var(--ink-soft);}
.crumbs a:hover{color:var(--indigo);}

/* ---------- Byline ---------- */
.byline{
  display:flex;gap:.7rem;align-items:baseline;flex-wrap:wrap;
  border-top:1px solid var(--rule);border-bottom:1px solid var(--rule);
  padding:.85rem 0;margin:0 0 2.4rem;
  font-size:.88rem;color:var(--ink-soft);
}
.byline strong{color:var(--ink);font-weight:600;}
.byline .cred{font-family:'IBM Plex Mono',monospace;font-size:.72rem;letter-spacing:.05em;}

/* ---------- Callouts ---------- */
.note{
  background:var(--paper-raised);border:1px solid var(--rule);
  border-left:3px solid var(--indigo);
  padding:1.15rem 1.25rem;margin:1.9rem 0;border-radius:0 6px 6px 0;
}
.note p:last-child{margin-bottom:0;}
.note .label{
  font-family:'IBM Plex Mono',monospace;font-size:.7rem;
  letter-spacing:.13em;text-transform:uppercase;color:var(--indigo);
  display:block;margin-bottom:.45rem;
}
.note.warm{border-left-color:var(--highlighter);}
.note.warm .label{color:#9A7415;}

/* ---------- Tables ---------- */
.table-wrap{overflow-x:auto;margin:1.8rem 0;}
table{border-collapse:collapse;width:100%;font-size:.95rem;}
caption{
  text-align:left;font-family:'IBM Plex Mono',monospace;
  font-size:.7rem;letter-spacing:.12em;text-transform:uppercase;
  color:var(--ink-soft);padding-bottom:.6rem;
}
th,td{padding:.7rem .85rem;text-align:left;vertical-align:top;border-bottom:1px solid var(--rule);}
thead th{
  font-family:'IBM Plex Mono',monospace;font-size:.7rem;
  letter-spacing:.09em;text-transform:uppercase;color:var(--ink-soft);
  border-bottom:2px solid var(--ink);font-weight:500;
}
tbody tr:nth-child(even){background:rgba(255,255,255,.55);}

/* ---------- Cards / grid ---------- */
.grid{display:grid;gap:1rem;margin:1.75rem 0;}
@media(min-width:38rem){.grid.two{grid-template-columns:1fr 1fr;}}
@media(min-width:52rem){.grid.three{grid-template-columns:repeat(3,1fr);}}
.card{
  background:var(--paper-raised);border:1px solid var(--rule);
  border-radius:8px;padding:1.25rem 1.3rem;
  display:block;text-decoration:none;color:inherit;
  transition:border-color .15s ease,transform .15s ease;
}
a.card:hover{border-color:var(--indigo);transform:translateY(-2px);}
.card .kind{
  font-family:'IBM Plex Mono',monospace;font-size:.68rem;
  letter-spacing:.12em;text-transform:uppercase;color:var(--indigo);
  display:block;margin-bottom:.5rem;
}
.card h3{font-size:1.08rem;margin:0 0 .4rem;}
.card p{font-size:.92rem;color:var(--ink-soft);margin:0;max-width:none;}

/* ---------- Buttons ---------- */
.btn{
  display:inline-block;background:var(--indigo);color:#fff;
  font-family:'IBM Plex Sans',sans-serif;font-weight:600;font-size:1rem;
  padding:.85rem 1.6rem;border-radius:6px;border:none;cursor:pointer;
  text-decoration:none;transition:background .15s ease;
}
.btn:hover{background:var(--indigo-deep);color:#fff;}
.btn-ghost{background:transparent;color:var(--indigo);border:2px solid var(--rule);}
.btn-ghost:hover{background:var(--paper-raised);border-color:var(--indigo);color:var(--indigo);}

/* ---------- FAQ ---------- */
.faq{margin:1.5rem 0;max-width:var(--measure);}
.faq details{border-bottom:1px solid var(--rule);padding:.2rem 0;}
.faq summary{
  cursor:pointer;padding:.85rem 0;font-weight:600;list-style:none;
  display:flex;justify-content:space-between;gap:1rem;align-items:center;
}
.faq summary::-webkit-details-marker{display:none;}
.faq summary::after{content:"+";color:var(--indigo);font-size:1.3rem;line-height:1;}
.faq details[open] summary::after{content:"\2212";}
.faq details p{padding:0 0 .9rem;margin:0;color:var(--ink-soft);}

/* ---------- Sources ---------- */
.sources{font-size:.88rem;color:var(--ink-soft);}
.sources li{margin-bottom:.7em;}

/* ---------- Footer ---------- */
.site-foot{
  border-top:1px solid var(--rule);margin-top:4.5rem;
  padding:2.25rem 0 3rem;font-size:.88rem;color:var(--ink-soft);
}
.site-foot a{color:var(--ink-soft);}
.site-foot a:hover{color:var(--indigo);}
.foot-links{display:flex;flex-wrap:wrap;gap:.45rem 1.1rem;margin:.9rem 0 0;padding:0;list-style:none;}
.disclosure{font-size:.8rem;margin-top:1.2rem;max-width:38rem;}

/* ---------- Quiz ---------- */
.quiz-card{
  background:var(--paper-raised);border:1px solid var(--rule);
  border-radius:10px;padding:1.75rem 1.5rem;margin:2rem 0;
}
.meter{height:4px;background:var(--rule);border-radius:99px;overflow:hidden;margin-bottom:1.4rem;}
.meter i{display:block;height:100%;width:0;background:var(--indigo);transition:width .3s ease;}
.qnum{
  font-family:'IBM Plex Mono',monospace;font-size:.72rem;
  letter-spacing:.12em;text-transform:uppercase;color:var(--ink-soft);margin:0 0 .6rem;
}
.qtext{font-family:'Newsreader',serif;font-size:1.35rem;line-height:1.3;margin:0 0 1.3rem;}
.opts{display:grid;gap:.55rem;}
.opts button{
  font-family:'IBM Plex Sans',sans-serif;font-size:.98rem;font-weight:500;
  text-align:left;background:var(--paper);color:var(--ink);
  border:1.5px solid var(--rule);border-radius:6px;
  padding:.8rem 1rem;cursor:pointer;transition:border-color .12s,background .12s;
}
.opts button:hover{border-color:var(--indigo);background:#fff;}
.linkbtn{
  background:none;border:none;padding:0;margin-top:1.1rem;cursor:pointer;
  font-family:'IBM Plex Mono',monospace;font-size:.74rem;letter-spacing:.08em;
  color:var(--ink-soft);text-decoration:underline;text-underline-offset:3px;
}
.bars{margin:1.5rem 0;}
.bar-row{margin-bottom:1rem;}
.bar-head{display:flex;justify-content:space-between;font-size:.9rem;margin-bottom:.35rem;}
.bar-head b{font-weight:600;}
.bar-track{height:10px;background:var(--rule);border-radius:99px;overflow:hidden;}
.bar-fill{height:100%;border-radius:99px;transition:width .5s ease;}
.f-deep{background:var(--indigo);}
.f-surf{background:var(--highlighter);}
.f-strat{background:var(--moss);}
.hidden{display:none !important;}

/* ---------- Email capture ---------- */
.optin-block{
  background:var(--ink);border-radius:10px;
  padding:1.6rem 1.5rem;margin:2.5rem 0;color:var(--paper);
  position:relative;overflow:hidden;
}
.optin-block::after{
  content:"";position:absolute;right:-40px;top:-40px;
  width:140px;height:140px;border-radius:50%;
  background:var(--indigo);opacity:.35;
}
.optin-block > *{position:relative;z-index:1;}
.optin-block .kind{
  font-family:'IBM Plex Mono',monospace;font-size:.68rem;
  letter-spacing:.14em;text-transform:uppercase;color:var(--highlighter);
  display:block;margin-bottom:.6rem;
}
.optin-block h3{
  font-family:'Newsreader',serif;font-weight:600;font-size:1.35rem;
  color:var(--paper);margin:0 0 .5rem;line-height:1.22;
}
.optin-block p{color:#C8CCD8;font-size:.95rem;margin:0 0 1rem;max-width:32rem;}
.optin-block .fields{display:grid;gap:.6rem;max-width:26rem;}
@media(min-width:34rem){.optin-block .fields{grid-template-columns:1fr 1fr;}}
.optin-block input{
  font-family:'IBM Plex Sans',sans-serif;font-size:.95rem;
  padding:.75rem .85rem;border-radius:6px;border:2px solid transparent;
  background:#fff;color:var(--ink);width:100%;
}
.optin-block input:focus-visible{outline:none;border-color:var(--highlighter);}
.optin-block .btn{
  background:var(--highlighter);color:#2E2508;margin-top:.7rem;
  font-weight:600;
}
.optin-block .btn:hover{background:#E7B93C;color:#2E2508;}
.optin-block .fine{font-size:.78rem;color:#9BA3B5;margin:.8rem 0 0;}
.optin-done{text-align:left;}
.optin-done h3{margin-bottom:.5rem;}
.optin-done .btn{display:inline-block;margin-top:.2rem;}
.optin-hidden{display:none !important;}