/* ClassEasy design system.
   Deep green primary (growth, and distinct from the blue every edtech uses),
   clay orange accent. High contrast for sunlight legibility on cheap screens.
   Sized for a 5-inch phone first; the grid widens on desktop. */
:root {
  --brand: #0b6e4f;
  --brand-dark: #085740;
  --brand-tint: #eef4f1;
  --accent: #c7511f;
  --accent-tint: #fdf1ea;
  --ink: #1a1a2e;
  --muted: #5b5b6b;
  --line: #e2e2ea;
  --bg: #fbfbfc;
  --card: #ffffff;
  --ok: #0b6e4f;
  --warn: #b7791f;
  --bad: #c53030;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(26, 26, 46, .06), 0 4px 12px rgba(26, 26, 46, .04);
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand: #3fa585; --brand-dark: #64c0a2; --brand-tint: #14251f;
    --accent: #e8834f; --accent-tint: #2a1a12;
    --ink: #eef0f4; --muted: #a2a2b4; --line: #2b2b38;
    --bg: #131320; --card: #1b1b2a;
    --shadow: 0 1px 2px rgba(0,0,0,.4), 0 4px 12px rgba(0,0,0,.25);
  }
}
* { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  -webkit-text-size-adjust: 100%;
}
a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }

header.top {
  background: var(--card); border-bottom: 1px solid var(--line);
  position: sticky; top: 0; z-index: 20;
}
.top-in {
  max-width: 1120px; margin: 0 auto; padding: 12px 16px;
  display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
}
.logo { font-weight: 800; font-size: 19px; color: var(--brand); letter-spacing: -.4px; }
.logo span { color: var(--accent); }
nav.top-nav { display: flex; gap: 14px; margin-left: auto; font-size: 14px; }
nav.top-nav a { color: var(--muted); font-weight: 600; }
nav.top-nav a.on { color: var(--brand); }

main { max-width: 1120px; margin: 0 auto; padding: 20px 16px 64px; }
h1 { font-size: 26px; margin: 6px 0 4px; letter-spacing: -.5px; }
h2 { font-size: 19px; margin: 28px 0 10px; }
h3 { font-size: 16px; margin: 20px 0 6px; }
.sub { color: var(--muted); margin: 0 0 20px; font-size: 15px; }

.grid { display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); }
.card {
  background: var(--card); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 14px; box-shadow: var(--shadow);
}
a.card { color: inherit; display: block; }
a.card:hover { border-color: var(--brand); text-decoration: none; }
.card .emoji { font-size: 26px; }
.card h3 { margin: 6px 0 2px; font-size: 16px; }
.meta { color: var(--muted); font-size: 13px; }

.pill {
  display: inline-block; padding: 2px 8px; border-radius: 99px;
  font-size: 11px; font-weight: 700; letter-spacing: .3px;
  background: var(--brand-tint); color: var(--brand-dark);
}
.pill.warn { background: var(--accent-tint); color: var(--accent); }
.pill.grey { background: var(--line); color: var(--muted); }

/* Provisional-content banner: the MVP ships AI-generated, machine-checked
   material that no human has signed off yet. Say so, plainly, every time. */
.banner {
  background: var(--accent-tint); border-left: 4px solid var(--accent);
  border-radius: 8px; padding: 12px 14px; margin: 0 0 18px; font-size: 14px;
}
.banner b { color: var(--accent); }

.bar { height: 6px; background: var(--line); border-radius: 99px; overflow: hidden; margin-top: 8px; }
.bar > i { display: block; height: 100%; background: var(--brand); border-radius: 99px; }

table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); }
th { color: var(--muted); font-size: 12px; text-transform: uppercase; letter-spacing: .4px; }
.scroll { overflow-x: auto; }

.term { margin: 18px 0; }
.term > h3 { display: flex; align-items: center; gap: 10px; }
.module { border: 1px solid var(--line); border-radius: var(--radius); margin: 10px 0; background: var(--card); }
.module > .mhead {
  padding: 10px 14px; border-bottom: 1px solid var(--line);
  display: flex; gap: 10px; align-items: center; font-weight: 700; font-size: 15px;
}
.topic {
  display: flex; align-items: center; gap: 12px; padding: 10px 14px;
  border-bottom: 1px solid var(--line); color: inherit;
}
.topic:last-child { border-bottom: 0; }
.topic:hover { background: var(--brand-tint); text-decoration: none; }
.topic .wk { font-size: 12px; color: var(--muted); min-width: 34px; }
.topic .t { flex: 1; min-width: 0; }
.topic .t b { display: block; font-weight: 600; font-size: 15px; }

.ring { width: 30px; height: 30px; flex: none; }
.ring circle { fill: none; stroke-width: 4; }
.ring .bgc { stroke: var(--line); }
.ring .fg { stroke: var(--brand); stroke-linecap: round; transform: rotate(-90deg); transform-origin: 50% 50%; }

.btn {
  display: inline-block; background: var(--brand); color: #fff; border: 0;
  padding: 10px 18px; border-radius: 10px; font-weight: 700; font-size: 15px;
  cursor: pointer; font-family: inherit;
}
.btn:hover { background: var(--brand-dark); text-decoration: none; }
.btn.ghost { background: transparent; color: var(--brand); border: 1px solid var(--line); }
.btn:disabled { opacity: .5; cursor: default; }

.lesson { max-width: 44rem; font-size: 17px; line-height: 1.65; }
.lesson h3 { margin-top: 26px; }
.lesson p { margin: 0 0 14px; }
.lesson strong { color: var(--brand-dark); }
.lesson ul, .lesson ol { margin: 0 0 14px; padding-left: 22px; }
.hook { background: var(--brand-tint); border-radius: var(--radius); padding: 14px 16px; font-size: 16px; }
.example { border: 1px solid var(--line); border-radius: var(--radius); padding: 12px 14px; margin: 12px 0; background: var(--card); }
.example ol { margin: 8px 0 0; }

.q { border: 1px solid var(--line); border-radius: var(--radius); padding: 14px; margin: 12px 0; background: var(--card); }
.q .qt { font-weight: 600; margin-bottom: 10px; }
.opt {
  display: block; width: 100%; text-align: left; padding: 10px 12px; margin: 6px 0;
  border: 1px solid var(--line); border-radius: 10px; background: var(--card);
  color: inherit; font: inherit; cursor: pointer;
}
.opt:hover { border-color: var(--brand); }
.opt.sel { border-color: var(--brand); background: var(--brand-tint); }
.opt.right { border-color: var(--ok); background: var(--brand-tint); }
.opt.wrong { border-color: var(--bad); background: #fdecec; }
@media (prefers-color-scheme: dark) { .opt.wrong { background: #2d1618; } }
.fb { margin-top: 10px; padding: 10px 12px; border-radius: 8px; background: var(--brand-tint); font-size: 14px; }
.fb.bad { background: var(--accent-tint); }

.heat { border-collapse: separate; border-spacing: 2px; font-size: 12px; }
.heat td.c { width: 22px; height: 22px; border-radius: 4px; padding: 0; }
.heat th.rot { height: 120px; white-space: nowrap; vertical-align: bottom; }
.heat th.rot > div { transform: rotate(-60deg); transform-origin: left bottom; width: 22px; font-weight: 500; font-size: 11px; }
.empty { color: var(--muted); padding: 28px; text-align: center; border: 1px dashed var(--line); border-radius: var(--radius); }

/* ---------------------------------------------------------------------------
   App shell: responsive nav, footer, landing page.
   Mobile-first — the nav collapses behind a button below 760px because the
   primary device is a 5-inch phone.
   --------------------------------------------------------------------------- */
.navtoggle {
  display: none; margin-left: auto; background: none; border: 0;
  font-size: 22px; color: var(--ink); cursor: pointer; padding: 4px 8px;
}
nav.top-nav a.navcta {
  background: var(--brand); color: #fff; padding: 6px 14px; border-radius: 99px;
}
nav.top-nav a.navcta:hover { background: var(--brand-dark); text-decoration: none; }

@media (max-width: 760px) {
  .navtoggle { display: block; }
  nav.top-nav {
    display: none; width: 100%; margin-left: 0; flex-direction: column;
    gap: 2px; padding-top: 10px;
  }
  nav.top-nav.open { display: flex; }
  nav.top-nav a { padding: 9px 2px; border-top: 1px solid var(--line); }
  nav.top-nav a.navcta { text-align: center; margin-top: 8px; border-top: 0; }
}

main.wide { max-width: 1320px; }

/* --- footer --------------------------------------------------------------- */
.site-foot {
  border-top: 1px solid var(--line); background: var(--card); margin-top: 56px;
}
.foot-in {
  max-width: 1120px; margin: 0 auto; padding: 34px 16px 20px;
  display: grid; gap: 26px; grid-template-columns: 1.6fr repeat(3, 1fr);
}
@media (max-width: 760px) { .foot-in { grid-template-columns: 1fr 1fr; } }
.foot-in h4 { font-size: 13px; text-transform: uppercase; letter-spacing: .5px;
  color: var(--muted); margin: 0 0 8px; }
.foot-in a { display: block; font-size: 14px; padding: 3px 0; color: var(--ink); }
.foot-in a:hover { color: var(--brand); }
.foot-bottom {
  max-width: 1120px; margin: 0 auto; padding: 14px 16px 30px;
  border-top: 1px solid var(--line); display: flex; gap: 14px;
  flex-wrap: wrap; justify-content: space-between; font-size: 13px; color: var(--muted);
}

.banner.guest { background: var(--brand-tint); border-left-color: var(--brand); }
.banner.guest a { font-weight: 700; }

/* --- landing -------------------------------------------------------------- */
.hero { padding: 54px 0 34px; }
.hero h1 {
  font-size: clamp(32px, 6vw, 52px); line-height: 1.08; letter-spacing: -1.2px;
  margin: 0 0 14px; max-width: 18ch;
}
.hero h1 em { font-style: normal; color: var(--brand); }
.hero p.lead { font-size: 19px; color: var(--muted); max-width: 54ch; margin: 0 0 24px; }
.hero .cta { display: flex; gap: 10px; flex-wrap: wrap; }
.btn.lg { padding: 13px 26px; font-size: 17px; }

.stats { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); margin: 30px 0; }
.stat { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; }
.stat b { display: block; font-size: 27px; color: var(--brand); letter-spacing: -.5px; }
.stat span { font-size: 13px; color: var(--muted); }

.feat { display: grid; gap: 14px; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.feat .card h3 { margin: 8px 0 4px; }
.section-head { margin: 46px 0 6px; }
.section-head + p.sub { margin-bottom: 18px; }