/* Layout: one reading column — books grid on top, checkout as a stacked form below,
   a sticky cart bar on phones. Covers are drawn in CSS like printed textbook fronts. */
:root {
  --bg: #f4f6f8;
  --surface: #ffffff;
  --sunk: #e9eef2;
  --ink: #13212e;
  --muted: #5a6b79;
  --line: #d6dee5;
  --accent: #1b8048;          /* Science Platform green pill */
  --accent-ink: #ffffff;
  --accent-soft: #e3f2e9;
  --blue: #1d4a73;
  --warn: #9a5b00;
  --warn-soft: #fdf1dc;
  --bad: #b3261e;
  --bad-soft: #fbe4e2;
  --display: "Bricolage Grotesque", "Hind Siliguri", system-ui, sans-serif;
  --body: "Hind Siliguri", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
  --r: 10px;
  --lg-light: block; --lg-dark: none;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0d141a; --surface: #151f28; --sunk: #1b2833; --ink: #e6edf2; --muted: #9aacba;
    --line: #2a3a47; --accent: #43b874; --accent-ink: #062012; --accent-soft: #163526;
    --blue: #8fb8de; --warn: #f0b456; --warn-soft: #3a2b12; --bad: #f08a80; --bad-soft: #3d1c19;
    --lg-light: none; --lg-dark: block;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0d141a; --surface: #151f28; --sunk: #1b2833; --ink: #e6edf2; --muted: #9aacba;
  --line: #2a3a47; --accent: #43b874; --accent-ink: #062012; --accent-soft: #163526;
  --blue: #8fb8de; --warn: #f0b456; --warn-soft: #3a2b12; --bad: #f08a80; --bad-soft: #3d1c19;
  --lg-light: none; --lg-dark: block;
  color-scheme: dark;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
body {
  background: var(--bg); color: var(--ink); font: 16px/1.55 var(--body); margin: 0;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}
.wrap { max-width: 1040px; margin: 0 auto; }
h1, h2, h3 { font-family: var(--display); line-height: 1.15; text-wrap: balance; margin: 0; }
h2 { font-size: 1.5rem; font-weight: 700; }
h3 { font-size: 1.08rem; font-weight: 650; }
a { color: var(--blue); }
.muted { color: var(--muted); }
.mono, .num { font-family: var(--mono); font-variant-numeric: tabular-nums; }
.small { font-size: .88rem; }

/* header */
.top { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 10px 12px; padding-block: 18px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--ink); }
.brand { gap: 12px; }
.logo img { height: 40px; width: auto; }
.logo .lg-light { display: var(--lg-light); } .logo .lg-dark { display: var(--lg-dark); }
.brand-sub { font: 700 .8rem var(--display); letter-spacing: .08em; text-transform: uppercase; color: var(--muted);
  border-left: 1px solid var(--line); padding-left: 12px; }
@media (max-width: 420px) { .logo img { height: 32px; } .brand-sub { font-size: .7rem; padding-left: 8px; } }
.hero .author { font-size: .95rem; color: var(--muted); } .hero .author b { color: var(--ink); }
.by-line { font-size: .84rem; color: var(--muted); }
.brand-mark { width: 38px; height: 38px; border-radius: 9px; background: var(--ink); color: var(--bg);
  display: grid; place-items: center; font: 800 15px/1 var(--display); letter-spacing: .02em; }
.brand-text b { display: block; font: 700 1rem/1.1 var(--display); }
.brand-text span { font-size: .8rem; color: var(--muted); }
.cart-btn { display: inline-flex; align-items: center; gap: 8px; border: 1px solid var(--line); background: var(--surface);
  color: var(--ink); border-radius: 999px; padding: 8px 14px; font: 600 .95rem var(--body); cursor: pointer; }
.cart-btn .count { background: var(--accent); color: var(--accent-ink); border-radius: 999px; min-width: 22px; height: 22px;
  display: inline-grid; place-items: center; font: 600 .8rem var(--mono); padding: 0 6px; }

/* hero */
.hero { padding-block: 22px 30px; display: grid; gap: 14px; }
.pill { display: inline-block; width: fit-content; background: var(--accent); color: var(--accent-ink);
  font: 700 .78rem/1 var(--display); letter-spacing: .08em; text-transform: uppercase; padding: 7px 12px; border-radius: 999px; }
.hero h1 { font-size: clamp(2rem, 6vw, 3.3rem); font-weight: 800; letter-spacing: -.02em; max-width: 16ch; }
.hero p { margin: 0; max-width: 60ch; color: var(--muted); font-size: 1.05rem; }
.facts { display: flex; flex-wrap: wrap; gap: 8px 18px; font-size: .92rem; }
.facts span { display: inline-flex; gap: 6px; align-items: baseline; }
.facts b { font-family: var(--mono); font-weight: 600; }

/* books */
.filters { display: grid; gap: 8px; margin-bottom: 14px; }
.filters .chips { display: flex; gap: 8px; flex-wrap: wrap; }
.chip { border: 1px solid var(--line); background: transparent; color: var(--ink); border-radius: 999px;
  padding: 6px 14px; font: 600 .9rem var(--body); cursor: pointer; }
.chip[aria-pressed="true"] { background: var(--ink); color: var(--bg); border-color: var(--ink); }
.grid { display: grid; gap: 18px; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); }
.book { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); padding: 14px;
  display: grid; grid-template-rows: auto auto 1fr auto; gap: 12px; min-width: 0; }
.cover { aspect-ratio: 3 / 4; max-width: 100%; border-radius: 4px 8px 8px 4px; position: relative; overflow: hidden;
  background: var(--c1); color: #fff; padding: 16px 16px 14px 26px; display: flex; flex-direction: column; justify-content: space-between;
  box-shadow: inset 8px 0 0 rgba(0,0,0,.22), inset 9px 0 0 rgba(255,255,255,.12); }
.cover img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; z-index: 1; }
.cover:has(img) { box-shadow: 0 1px 3px rgba(0,0,0,.18); }
.cover:has(img)::after { display: none; }
.cover .lvl { font: 800 .72rem/1 var(--display); letter-spacing: .16em; opacity: .85; }
.cover .t { font: 800 1.35rem/1.08 var(--display); letter-spacing: -.01em; text-wrap: balance; }
.cover .eq { font: 500 1.05rem var(--mono); opacity: .9; border-top: 1px solid rgba(255,255,255,.35); padding-top: 8px; }
.cover .by { font: 600 .72rem/1.2 var(--body); opacity: .8; }
.cover::after { content: ""; position: absolute; right: -40px; top: -40px; width: 140px; height: 140px; border-radius: 50%;
  border: 18px solid rgba(255,255,255,.08); }
.book-info { display: grid; gap: 4px; align-content: start; min-width: 0; }
.book-info p { margin: 0; font-size: .9rem; color: var(--muted); }
.price { font: 600 1.15rem var(--mono); font-variant-numeric: tabular-nums; display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 8px; }
.price .mrp { font-size: .9rem; font-weight: 500; color: var(--muted); }
.price .off { font: 700 .72rem var(--body); background: var(--accent-soft); color: var(--accent); border-radius: 999px; padding: 2px 8px; }
.buy { display: grid; gap: 8px; }
.row { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 8px; overflow: hidden; }
.seg button { border: 0; background: transparent; color: var(--ink); padding: 6px 12px; font: 600 .88rem var(--body); cursor: pointer; }
.seg button[aria-pressed="true"] { background: var(--accent-soft); color: var(--accent); }
.qty { display: inline-flex; align-items: center; border: 1px solid var(--line); border-radius: 8px; }
.qty button { width: 34px; height: 34px; border: 0; background: transparent; color: var(--ink); font-size: 1.1rem; cursor: pointer; }
.qty span { min-width: 26px; text-align: center; font-family: var(--mono); }

.btn { border: 0; border-radius: 8px; padding: 11px 16px; font: 700 .98rem var(--body); cursor: pointer;
  background: var(--accent); color: var(--accent-ink); }
.btn:hover { filter: brightness(1.05); }
.btn.ghost { background: transparent; color: var(--ink); border: 1px solid var(--line); }
.btn.wide { width: 100%; }
.btn[disabled] { opacity: .55; cursor: not-allowed; }
:focus-visible { outline: 3px solid var(--blue); outline-offset: 2px; }

/* checkout */
.checkout { margin-block: 42px 120px; display: grid; gap: 22px; grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr); align-items: start; }
@media (max-width: 820px) { .checkout { grid-template-columns: minmax(0, 1fr); } }
fieldset { border: 0; padding: 0; margin: 0 0 26px; display: grid; gap: 12px; min-width: 0; }
legend { font: 700 1.1rem var(--display); margin-bottom: 4px; padding: 0; }
label { display: grid; gap: 5px; font-weight: 600; font-size: .92rem; }
label .hint { font-weight: 400; color: var(--muted); font-size: .84rem; }
input, select, textarea { font: 16px var(--body); color: var(--ink); background: var(--surface); border: 1px solid var(--line);
  border-radius: 8px; padding: 10px 12px; width: 100%; }
textarea { min-height: 76px; resize: vertical; }
.two { display: grid; gap: 12px; grid-template-columns: 1fr 1fr; }
@media (max-width: 520px) { .two { grid-template-columns: 1fr; } }
.options { display: grid; gap: 8px; }
.opt { display: grid; grid-template-columns: auto 1fr auto; gap: 10px; align-items: start; border: 1px solid var(--line);
  background: var(--surface); border-radius: var(--r); padding: 12px 14px; cursor: pointer; font-weight: 400; }
.opt:has(input:checked) { border-color: var(--accent); box-shadow: 0 0 0 1px var(--accent); }
.opt input { width: 18px; height: 18px; margin: 3px 0 0; accent-color: var(--accent); }
.opt b { display: block; font-weight: 650; }
.opt small { color: var(--muted); display: block; line-height: 1.4; }
.opt .num { font-weight: 600; white-space: nowrap; }
.tabs { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }

.summary { position: sticky; top: calc(env(safe-area-inset-top, 0px) + 16px); background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--r); padding: 18px; display: grid; gap: 12px; }
.lines { display: grid; gap: 8px; }
.line { display: grid; grid-template-columns: 1fr auto; gap: 10px; font-size: .94rem; align-items: start; }
.line .x { display: inline-flex; gap: 6px; align-items: center; }
.line .rm { border: 0; background: none; color: var(--muted); cursor: pointer; font-size: .82rem; text-decoration: underline; padding: 0; }
.split { border-top: 1px dashed var(--line); padding-top: 12px; display: grid; gap: 8px; }
.pay-box { border-radius: 8px; padding: 12px; display: grid; gap: 2px; }
.pay-box.now { background: var(--accent-soft); }
.pay-box.door { background: var(--sunk); }
.pay-box .k { font-size: .82rem; color: var(--muted); }
.pay-box .v { font: 700 1.4rem var(--mono); font-variant-numeric: tabular-nums; }
.pay-box.now .v { color: var(--accent); }
.empty { text-align: center; padding: 18px 6px; color: var(--muted); }

.notice { border-radius: 8px; padding: 10px 12px; font-size: .92rem; }
.notice.bad { background: var(--bad-soft); color: var(--bad); }
.notice.warn { background: var(--warn-soft); color: var(--warn); }
.notice.ok { background: var(--accent-soft); color: var(--accent); }

.bar { position: fixed; left: 0; right: 0; bottom: 0; z-index: 20; background: var(--surface); border-top: 1px solid var(--line);
  padding: 10px max(16px, env(safe-area-inset-right, 0px)) calc(10px + env(safe-area-inset-bottom, 0px)) max(16px, env(safe-area-inset-left, 0px));
  display: flex; justify-content: space-between; align-items: center; gap: 12px; }
@media (min-width: 821px) { .bar { display: none; } }

footer { border-top: 1px solid var(--line); padding-block: 24px 90px; color: var(--muted); font-size: .88rem; display: grid; gap: 6px; }
.hp { position: absolute; left: -9999px; width: 1px; height: 1px; overflow: hidden; }

/* receipt + admin shared */
.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); padding: 18px; }
.status { display: inline-flex; align-items: center; gap: 6px; border-radius: 999px; padding: 4px 10px; font: 600 .82rem var(--body);
  background: var(--sunk); color: var(--ink); white-space: nowrap; }
.status::before { content: ""; width: 8px; height: 8px; border-radius: 50%; background: currentColor; opacity: .7; }
.st-new, .st-confirmed { background: var(--accent-soft); color: var(--accent); }
.st-awaiting_payment, .st-packed, .st-ready_pickup { background: var(--warn-soft); color: var(--warn); }
.st-payment_failed, .st-cancelled, .st-returned { background: var(--bad-soft); color: var(--bad); }
.st-shipped { background: var(--sunk); color: var(--blue); }

@media (prefers-reduced-motion: no-preference) {
  .book { transition: transform .15s ease; }
  .book:hover { transform: translateY(-2px); }
}

.tag { display: inline-block; width: fit-content; margin-top: 4px; font: 600 .76rem var(--body); color: var(--warn);
  background: var(--warn-soft); border-radius: 999px; padding: 2px 9px; }
.opt:has(input:disabled) { opacity: .5; cursor: not-allowed; }

/* version switch — first thing on every book card */
.ver { display: grid; gap: 6px; }
.ver-k { font: 700 .74rem var(--body); letter-spacing: .04em; color: var(--muted); }
.ver-btns { display: grid; grid-template-columns: 1fr 1fr; gap: 6px; }
.ver-btns button { border: 2px solid var(--line); background: var(--surface); color: var(--ink); border-radius: 10px;
  padding: 9px 6px; font: 700 .95rem/1.15 var(--body); cursor: pointer; }
.ver-btns button[aria-pressed="true"] { background: var(--accent); border-color: var(--accent); color: var(--accent-ink);
  box-shadow: 0 2px 0 rgba(0,0,0,.12); }
.ver-btns button[aria-pressed="true"]::before { content: "✓ "; }
.ver-flag { position: absolute; z-index: 2; top: 10px; right: 10px; background: var(--accent); color: var(--accent-ink);
  font: 700 .78rem var(--body); padding: 4px 10px; border-radius: 999px; box-shadow: 0 2px 6px rgba(0,0,0,.25); }
.ver-chip { display: inline-block; font: 700 .74rem var(--body); padding: 1px 8px; border-radius: 999px; vertical-align: 1px; }
.ver-chip.bn { background: var(--accent-soft); color: var(--accent); }
.ver-chip.en { background: var(--sunk); color: var(--blue); }

@media (max-width: 420px) { .track-link { padding: 8px 10px; font-size: .85rem; } }
@media (max-width: 420px) { .brand-sub { display: none; } }

/* look inside */
.meta-line { font-size: .84rem; color: var(--muted); }
.look { justify-self: start; border: 0; background: none; padding: 2px 0; color: var(--blue); font: 700 .92rem var(--body); cursor: pointer; text-decoration: underline; text-underline-offset: 3px; }
.cover[data-look] { cursor: zoom-in; }
.li { position: fixed; inset: 0; z-index: 40; background: rgba(8, 16, 22, .55); overflow-y: auto;
  padding: calc(env(safe-area-inset-top, 0px) + 24px) max(12px, env(safe-area-inset-right, 0px)) calc(env(safe-area-inset-bottom, 0px) + 24px) max(12px, env(safe-area-inset-left, 0px)); }
.li-box { position: relative; max-width: 980px; margin: 0 auto; background: var(--surface); border-radius: 14px; padding: 22px; display: block; }
.li-close { position: absolute; top: 10px; right: 10px; width: 40px; height: 40px; border-radius: 50%; border: 1px solid var(--line);
  background: var(--surface); color: var(--ink); font-size: 1.5rem; line-height: 1; cursor: pointer; z-index: 2; }
#liBody { display: grid; gap: 18px; }
.li-head { padding-right: 46px; display: grid; gap: 4px; } .li-head h2 { font-size: clamp(1.3rem, 3.5vw, 1.8rem); }
.li-ver { max-width: 420px; }
.li-grid { display: grid; gap: 24px; grid-template-columns: minmax(0, 340px) minmax(0, 1fr); align-items: start; }
@media (max-width: 760px) { .li-grid { grid-template-columns: minmax(0, 1fr); } .li-gallery { max-width: 360px; } }
.li-gallery { display: grid; gap: 10px; }
.li-main img, .li-ph { width: 100%; aspect-ratio: 600 / 849; object-fit: cover; border-radius: 6px; box-shadow: 0 2px 10px rgba(0,0,0,.18); display: block; }
.li-ph { display: grid; place-items: center; background: var(--sunk); color: var(--muted); font-weight: 700; padding: 20px; text-align: center; }
.li-thumbs { display: flex; gap: 10px; }
.li-thumbs button { border: 2px solid var(--line); border-radius: 8px; padding: 4px; background: var(--surface); color: var(--ink); cursor: pointer;
  display: grid; gap: 4px; font: 600 .78rem var(--body); width: 84px; }
.li-thumbs button[aria-pressed="true"] { border-color: var(--accent); }
.li-thumbs img { width: 100%; aspect-ratio: 600 / 849; object-fit: cover; border-radius: 3px; }
.li-info { display: grid; gap: 12px; min-width: 0; }
.li-info p { margin: 0; max-width: 62ch; }
.li-info h3 { margin-top: 6px; }
.li-tag { font: 700 1.15rem var(--display); }
.li-facts { display: grid; grid-template-columns: auto 1fr; gap: 4px 16px; margin: 0; font-size: .95rem; }
.li-facts dt { color: var(--muted); } .li-facts dd { margin: 0; }
.li-inside { border-collapse: collapse; width: 100%; max-width: 420px; font-size: .95rem; }
.li-inside td { padding: 6px 0; border-bottom: 1px solid var(--line); } .li-inside td.num { text-align: right; font-weight: 600; }
.li-toc { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 4px 16px; font-size: .95rem; }
.li-toc li { display: flex; gap: 10px; } .li-toc .num { color: var(--muted); }
.li-buy { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; padding-top: 6px; }
.li-sample { border-top: 1px solid var(--line); padding-top: 16px; display: grid; gap: 10px; }
.li-pages { display: grid; gap: 14px; justify-items: center; }
.li-page { margin: 0; display: grid; gap: 4px; justify-items: center; max-width: 100%; }
.li-page canvas { max-width: 100%; height: auto; border: 1px solid var(--line); background: #fff; box-shadow: 0 1px 4px rgba(0,0,0,.12); }
.li-page figcaption { font-size: .8rem; color: var(--muted); }

.tags { display: flex; flex-wrap: wrap; gap: 6px; } .tags:empty { display: none; }
.tag.pre { color: var(--blue); background: var(--sunk); }
.pre-txt { color: var(--blue); }