:root{
  --ink:#141412; --body:#33332E; --grey:#6F6F6A; --rule:#E7E7E2;
  --paper:#FFFFFF; --card:#FCFCFA; --accent:#503A8C; --accent-soft:rgba(80,58,140,.07);
  --display:'Fraunces',Georgia,serif; --sans:'Inter',system-ui,sans-serif;
}
*{box-sizing:border-box}
html,body{margin:0;height:100%}
body{font-family:var(--sans);color:var(--ink);background:var(--paper);font-size:17px;line-height:1.7;overflow:hidden}
a{color:var(--ink);text-decoration:none}
:focus-visible{outline:2px solid var(--accent);outline-offset:3px}
::selection{background:var(--accent);color:#fff}

/* ---------- transform-based slide track ---------- */
.viewport{height:100vh;width:100vw;overflow:hidden}
main{
  height:100vh;display:flex;
  transition:transform .65s cubic-bezier(.22,.61,.36,1);
  will-change:transform;
}
@media(prefers-reduced-motion:reduce){main{transition:none}}
section.panel{
  min-width:100vw;width:100vw;height:100vh;flex:0 0 auto;
  overflow-y:auto;overflow-x:hidden;position:relative;
}
.inner{
  max-width:1180px;margin:0 auto;
  /* bottom padding floor reserves room for the fixed dots pill on short viewports */
  padding:clamp(44px,7vh,84px) clamp(28px,5vw,72px) clamp(76px,9vh,96px);
  min-height:100vh;display:flex;flex-direction:column;justify-content:center;
}
/* content-dense chapters anchor to the top so they breathe and scroll, not cram-to-center */
.panel.chapter .inner{justify-content:flex-start}

/* ---------- cover + index ---------- */
.cover .kicker{font-size:13px;letter-spacing:.14em;text-transform:uppercase;color:var(--grey);margin-bottom:28px}
.cover h1{font-family:var(--display);font-weight:560;font-size:clamp(38px,6.4vw,66px);line-height:1.03;letter-spacing:-.02em;margin:0 0 24px;max-width:16ch}
.cover h1 em{font-style:italic;font-weight:400;color:var(--accent)}
.cover .by{color:var(--grey);font-size:15px;margin:0 0 56px}
.index{border-top:1px solid var(--ink);max-width:640px}
.index a{display:flex;align-items:baseline;gap:20px;padding:18px 6px;border-bottom:1px solid var(--rule);transition:padding-left .2s ease,background .2s ease}
.index a:hover{padding-left:16px;background:var(--accent-soft)}
.index a:hover .t{color:var(--accent)}
.index .num{font-family:var(--display);font-style:italic;font-size:17px;color:var(--accent);flex:0 0 30px}
.index .t{font-size:17px}
.index .u{margin-left:auto;font-size:13px;color:var(--grey);white-space:nowrap}
@media(max-width:560px){.index .u{display:none}}
.cover .go{margin-top:36px;font-size:13px;letter-spacing:.04em;color:var(--grey)}

/* ---------- chapter header ---------- */
.ch-head{margin-bottom:clamp(22px,3vh,36px)}
.ch-num{font-family:var(--display);font-style:italic;font-weight:400;font-size:clamp(30px,4.4vw,44px);color:var(--accent);line-height:1;margin-bottom:14px}
.ch-tag{font-size:12px;letter-spacing:.14em;text-transform:uppercase;color:var(--grey);margin-bottom:10px}
h2{font-family:var(--display);font-weight:560;font-size:clamp(28px,4.4vw,42px);line-height:1.06;letter-spacing:-.015em;margin:0}

/* ---------- two-column body ---------- */
.cols{display:grid;grid-template-columns:1fr 1fr;gap:clamp(40px,5vw,72px);align-items:start}
@media(max-width:820px){.cols{grid-template-columns:1fr;gap:36px}}

.prose p{margin:0 0 22px;color:var(--body);font-size:17px;line-height:1.72;max-width:62ch}
.prose p:last-child{margin-bottom:0}
.lead-in{display:block;font-family:var(--display);font-style:italic;color:var(--ink);font-weight:560;font-size:18px;line-height:1.2;margin-bottom:5px}
.lead-in::after{content:none}

/* worked example, grouped as one quiet card so it reads as a unit and the prose gets its own air */
.example{
  background:var(--card);border:1px solid var(--rule);border-radius:10px;
  padding:clamp(24px,3vw,34px);
}
.exhead{font-size:12px;letter-spacing:.14em;text-transform:uppercase;color:var(--accent);margin:0 0 18px}
.example p{margin:0 0 14px;color:var(--body);font-size:16px;line-height:1.68}
.boxed{display:inline-block;border:1.5px solid var(--accent);color:var(--accent);border-radius:5px;padding:9px 15px;font-size:14px;margin:8px 0 4px}
.dmath{text-align:center;margin:18px 0}

.fig{margin-top:20px}
.graph{
  height:clamp(210px,26vh,260px);border:1px solid var(--rule);border-radius:8px;overflow:hidden;background:#FBFBF9;
  display:flex;align-items:center;justify-content:center;color:var(--grey);font-size:13px;font-style:italic;
}
.figcap{font-size:12.5px;color:var(--grey);margin-top:12px;line-height:1.5}

/* ---------- reflection ---------- */
.reflect .cols{grid-template-columns:1fr;gap:clamp(32px,4vw,48px)}
.reflect .prose{max-width:72ch}
.reflect .q{font-family:var(--display);font-style:italic;font-size:clamp(20px,2.8vw,26px);line-height:1.3;margin:0 0 16px;color:var(--ink)}
.reflect .prose p{font-size:17px}

/* ---------- dots ---------- */
.dots{
  position:fixed;bottom:16px;left:50%;transform:translateX(-50%);
  display:flex;align-items:center;gap:12px;z-index:30;padding:8px 12px;border-radius:999px;
  background:rgba(255,255,255,.95);border:1px solid var(--rule);
  backdrop-filter:blur(6px);box-shadow:0 1px 12px rgba(20,20,18,.06);
}
.dots button[data-p]{all:unset;cursor:pointer;width:8px;height:8px;border-radius:50%;background:#D8D8D2;transition:background .2s,transform .2s}
.dots button[data-p]:hover{background:var(--grey)}
.dots button[data-p].on{background:var(--accent);transform:scale(1.35)}
.dots button:focus-visible{outline:2px solid var(--accent);outline-offset:3px}
.dots .arrow{all:unset;cursor:pointer;color:var(--grey);font-size:15px;line-height:1;padding:0 2px;transition:color .2s,opacity .2s}
.dots .arrow:hover{color:var(--accent)}
.dots .arrow[disabled]{opacity:.25;cursor:default}
.dots .arrow:first-child{margin-right:2px}
.dots .arrow:last-child{margin-left:2px}

/* ---------- mobile: plain vertical document ---------- */
@media(max-width:640px){
  body{overflow:auto}
  .viewport{height:auto;width:auto;overflow:visible}
  main{display:block;height:auto;transform:none!important;transition:none}
  section.panel{min-width:0;width:auto;height:auto;overflow:visible;border-bottom:1px solid var(--rule)}
  .inner{min-height:0;padding:56px 24px 64px;justify-content:flex-start}
  .dots{display:none}
}

/* ---------- print: same vertical-document fallback, one chapter per sheet ---------- */
@media print{
  body{overflow:visible}
  .viewport{height:auto;width:auto;overflow:visible}
  main{display:block;height:auto;transform:none!important;transition:none}
  section.panel{min-width:0;width:auto;height:auto;overflow:visible;page-break-after:always}
  .inner{min-height:0;padding:40px 0}
  .dots{display:none}
}