:root {
  --bg: #f3efe6;
  --bg-2: #e7f0e4;
  --card: #fffdf8;
  --ink: #1c1917;
  --muted: #57534e;
  --line: #e6dfd2;
  --shadow: 0 10px 28px rgba(70, 48, 20, 0.08);
  --good: #166534;
  --good-bg: #dcfce7;
  --bad: #991b1b;
  --bad-bg: #fee2e2;
  --hint: #92400e;
  --hint-bg: #fef3c7;
  --accent: #15803d;
  --accent-ink: #fff;
  --radius: 20px;
  --top: 64px;
  color-scheme: light dark;
  font-family: "Avenir Next", "Segoe UI", system-ui, sans-serif;
}

body[data-block="fundamento"] { --accent: #b45309; }
body[data-block="numeros"] { --accent: #1d4ed8; }
body[data-block="medida"] { --accent: #0f766e; }
body[data-block="algebra"] { --accent: #6d28d9; }
body[data-block="geometria"] { --accent: #15803d; }
body[data-block="datos"] { --accent: #c2410c; }

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1c1917;
    --bg-2: #14241c;
    --card: #292524;
    --ink: #fafaf9;
    --muted: #a8a29e;
    --line: #44403c;
    --shadow: 0 10px 28px rgba(0, 0, 0, 0.35);
    --good: #86efac;
    --good-bg: #14532d;
    --bad: #fca5a5;
    --bad-bg: #7f1d1d;
    --hint: #fcd34d;
    --hint-bg: #451a03;
  }
}

* { box-sizing: border-box; }
html {
  scroll-behavior: smooth;
  scroll-padding-top: 96px;
  scroll-padding-bottom: 140px;
}
body {
  margin: 0;
  background:
    radial-gradient(1200px 400px at 10% -10%, var(--bg-2), transparent 50%),
    var(--bg);
  color: var(--ink);
  font-size: 18px;
  line-height: 1.55;
  overflow-x: hidden;
}
img, svg { max-width: 100%; }
button, input { font: inherit; color: inherit; }
a { color: var(--accent); }
h1, h2, h3 { line-height: 1.25; margin: 0 0 0.6rem; }
p { margin: 0.7rem 0; }
.wrap {
  width: min(740px, 100%);
  margin: 0 auto;
  padding: 16px 16px calc(108px + env(safe-area-inset-bottom));
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 10px;
  min-height: var(--top);
  padding: 8px 12px;
  padding-top: calc(8px + env(safe-area-inset-top));
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.icon-btn, .navbtn, .opt, .step-next, .primary, .ghost {
  min-height: 44px;
  border-radius: 14px;
  border: 0;
  cursor: pointer;
}
.icon-btn {
  width: 44px;
  background: var(--card);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}
.brand { display: flex; flex-direction: column; min-width: 0; flex: 1; }
.brand b, .brand span { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.brand b { font-size: 16px; }
.brand span { color: var(--muted); font-size: 13px; }
.bar {
  flex: 1 1 100%;
  height: 8px;
  background: var(--line);
  border-radius: 99px;
  overflow: hidden;
}
.bar > i {
  display: block;
  height: 100%;
  width: 0;
  background: var(--accent);
  border-radius: inherit;
}
.dots {
  display: flex;
  gap: 6px;
  width: 100%;
  overflow-x: auto;
  padding-bottom: 2px;
}
.dots button {
  flex: 0 0 auto;
  width: 36px;
  height: 36px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--card);
  color: var(--ink);
  cursor: pointer;
}
.dots button.on { background: var(--accent); color: var(--accent-ink); border-color: transparent; }
.dots button.done { box-shadow: inset 0 0 0 2px var(--accent); }

.bottombar {
  position: fixed;
  left: 0; right: 0; bottom: 0;
  z-index: 20;
  display: flex;
  gap: 8px;
  padding: 10px 12px calc(10px + env(safe-area-inset-bottom));
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  backdrop-filter: blur(12px);
  border-top: 1px solid var(--line);
}
.navbtn {
  flex: 1;
  background: var(--accent);
  color: var(--accent-ink);
  font-weight: 700;
}
.navbtn.secondary { background: var(--card); color: var(--ink); border: 1px solid var(--line); }
.navbtn:disabled { opacity: 0.45; }

.backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  z-index: 30;
}
.sheet {
  position: fixed;
  left: 0; right: 0; bottom: 0;
  z-index: 31;
  max-height: min(85vh, 760px);
  overflow: auto;
  background: var(--card);
  border-radius: 22px 22px 0 0;
  padding: 12px 14px calc(20px + env(safe-area-inset-bottom));
  box-shadow: var(--shadow);
}
.sheet h2 { font-size: 20px; }
.sheet a.row {
  display: flex;
  justify-content: space-between;
  gap: 8px;
  padding: 10px 8px;
  border-radius: 12px;
  text-decoration: none;
  color: inherit;
}
.sheet a.row small { color: var(--muted); }
.sheet a.row.here { background: color-mix(in srgb, var(--accent) 16%, transparent); }
.block-label {
  margin: 14px 8px 4px;
  font-size: 13px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
}
.hidden { display: none !important; }

.hero h1 { font-size: clamp(30px, 7vw, 44px); letter-spacing: -0.03em; }
.lede { font-size: 18px; color: var(--muted); }
.banner {
  display: block;
  margin: 16px 0;
  padding: 18px;
  border-radius: var(--radius);
  background: linear-gradient(135deg, #166534, #22c55e);
  color: white;
  text-decoration: none;
  box-shadow: var(--shadow);
}
.banner span { opacity: 0.9; font-size: 14px; letter-spacing: 0.04em; text-transform: uppercase; }
.banner strong { display: block; font-size: 28px; margin: 4px 0; }
.banner em { font-style: normal; font-weight: 700; }
.actions { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0 20px; }
.primary, .ghost {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0 16px;
  text-decoration: none;
  font-weight: 700;
}
.primary { background: var(--accent); color: var(--accent-ink); }
.ghost { background: var(--card); color: var(--ink); border: 1px solid var(--line); }

.path { display: flex; flex-direction: column; gap: 8px; margin: 8px 0 22px; }
.path a {
  display: flex;
  gap: 10px;
  align-items: center;
  text-decoration: none;
  color: inherit;
  background: var(--card);
  border-radius: 14px;
  padding: 8px 10px;
  border: 1px solid var(--line);
}
.path .n {
  width: 32px; height: 32px; flex: none;
  display: grid; place-items: center;
  border-radius: 10px;
  background: var(--accent);
  color: var(--accent-ink);
  font-weight: 800;
  font-size: 14px;
}
.cards { display: grid; grid-template-columns: 1fr; gap: 10px; }
@media (min-width: 700px) {
  .cards { grid-template-columns: 1fr 1fr; }
}
.card {
  display: flex;
  flex-direction: column;
  gap: 4px;
  background: var(--card);
  border-radius: var(--radius);
  padding: 14px;
  text-decoration: none;
  color: inherit;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  border-top: 5px solid var(--c, var(--accent));
}
.card .badge, .badge {
  align-self: flex-start;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.03em;
  background: color-mix(in srgb, var(--c, var(--accent)) 18%, var(--card));
  color: var(--ink);
  border-radius: 999px;
  padding: 2px 8px;
}
.card small { color: var(--muted); }
.stars { color: #d97706; letter-spacing: 2px; font-size: 14px; }
.section-title { margin: 22px 0 8px; font-size: 22px; }

body[data-page="topic"] #content .lesson { display: none; }
body[data-page="topic"] #content .lesson.is-on { display: block; animation: rise 0.28s ease; }
@keyframes rise { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }
@media (prefers-reduced-motion: reduce) {
  .lesson { animation: none; }
  html { scroll-behavior: auto; }
}

.kicker { color: var(--accent); font-weight: 800; font-size: 13px; letter-spacing: 0.06em; text-transform: uppercase; }
.note {
  border-radius: 16px;
  padding: 12px 14px;
  margin: 12px 0;
  background: color-mix(in srgb, var(--accent) 12%, var(--card));
}
.note.life { background: color-mix(in srgb, #0f766e 14%, var(--card)); }
.note.watch { background: var(--hint-bg); color: var(--ink); }
.note b { display: block; margin-bottom: 2px; }
.formula {
  margin: 14px 0;
  padding: 14px;
  text-align: center;
  font-size: 28px;
  font-weight: 750;
  letter-spacing: 0.02em;
  background: var(--card);
  border-radius: 16px;
  border: 1px dashed var(--accent);
  overflow-x: auto;
}
.figure {
  background: var(--card);
  border-radius: 16px;
  padding: 8px;
  margin: 12px 0;
  border: 1px solid var(--line);
}
.figure svg { display: block; width: 100%; height: auto; }
.figure figcaption { color: var(--muted); font-size: 14px; padding: 4px 6px 6px; }
.term i { font-style: normal; color: var(--muted); font-weight: 650; font-size: 0.92em; }
.frac {
  display: inline-flex;
  flex-direction: column;
  vertical-align: middle;
  align-items: center;
  line-height: 1.05;
  font-size: 0.86em;
  margin: 0 0.15em;
}
.frac .n { border-bottom: 2px solid currentColor; padding: 0 0.25em 1px; }
.frac .d { padding: 1px 0.25em 0; }
.remind {
  font-size: 15px;
  color: var(--muted);
  background: var(--card);
  border-radius: 12px;
  padding: 8px 12px;
}
.steps { margin: 12px 0; }
.step {
  background: var(--card);
  border-radius: 14px;
  padding: 10px 12px;
  margin: 8px 0;
  border-left: 5px solid var(--accent);
}
.step .tag { font-size: 12px; font-weight: 800; color: var(--accent); letter-spacing: 0.04em; text-transform: uppercase; }
.step-next { margin-top: 6px; padding: 0 14px; background: var(--card); border: 1px solid var(--line); font-weight: 700; }

.trap { background: var(--card); border-radius: 16px; padding: 12px; margin: 10px 0; border: 1px solid var(--line); }
.trap .wrong, .trap .right { margin: 4px 0; border-radius: 10px; padding: 8px 10px; }
.trap .wrong { background: var(--bad-bg); }
.trap .right { background: var(--good-bg); }
.trap .lbl { display: block; font-size: 12px; font-weight: 800; letter-spacing: 0.04em; text-transform: uppercase; }
.parents { background: var(--card); border-radius: 16px; padding: 8px 14px; border: 1px solid var(--line); margin: 12px 0; }
.parents summary { cursor: pointer; font-weight: 800; min-height: 44px; display: flex; align-items: center; }
.table-wrap { overflow-x: auto; margin: 10px 0; }
table { width: 100%; border-collapse: collapse; background: var(--card); }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
pre.divbox {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  background: var(--card);
  border-radius: 14px;
  padding: 12px;
  overflow-x: auto;
  line-height: 1.35;
  font-size: 16px;
}

.check h3 { margin-top: 18px; }
.q {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 12px;
  margin: 10px 0;
  scroll-margin-bottom: 140px;
}
.q-k { color: var(--muted); font-size: 13px; font-weight: 700; }
.options { display: flex; flex-direction: column; gap: 8px; margin-top: 8px; }
.opt {
  text-align: left;
  padding: 10px 12px;
  background: var(--bg);
  border: 1px solid var(--line);
}
.opt.good { background: var(--good-bg); border-color: transparent; }
.opt.bad { background: var(--bad-bg); border-color: transparent; }
.num-row { display: flex; gap: 8px; margin-top: 8px; }
.num-row input {
  flex: 1;
  min-height: 48px;
  border-radius: 14px;
  border: 1px solid var(--line);
  background: var(--bg);
  padding: 0 12px;
  font-size: 20px;
}
.num-row button, .q-actions button {
  min-height: 48px;
  padding: 0 14px;
  border-radius: 14px;
  border: 0;
  background: var(--accent);
  color: var(--accent-ink);
  font-weight: 700;
  cursor: pointer;
}
.q-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 8px; }
.q-actions .linkish { background: transparent; color: var(--accent); border: 1px solid var(--line); }
.feedback { border-radius: 12px; padding: 8px 10px; margin-top: 8px; }
.feedback.good { background: var(--good-bg); }
.feedback.bad { background: var(--bad-bg); }
.feedback.hint { background: var(--hint-bg); }
.solution { white-space: pre-line; }
.gate {
  margin-top: 8px;
  color: var(--hint);
  font-weight: 700;
}
.summary {
  background: var(--card);
  border-radius: var(--radius);
  padding: 16px;
  border: 1px solid var(--line);
}
.summary a { display: block; margin: 6px 0; font-weight: 700; }
.search {
  width: 100%;
  min-height: 48px;
  border-radius: 14px;
  border: 1px solid var(--line);
  background: var(--card);
  padding: 0 14px;
  font-size: 18px;
}
.times { overflow-x: auto; margin: 10px 0; }
.times table { min-width: 520px; text-align: center; }
.times td, .times th { text-align: center; }
.times button {
  width: 100%;
  min-height: 40px;
  border: 0;
  background: transparent;
  cursor: pointer;
  font-weight: 700;
}
.widget {
  background: var(--card);
  border-radius: 16px;
  padding: 12px;
  border: 1px solid var(--line);
  margin: 12px 0;
}
.widget .num-row { margin-top: 8px; }

.noscript {
  margin: 20px;
  padding: 16px;
  background: var(--hint-bg);
  border-radius: 16px;
}