/* Engineering computation pad: faint graph grid, green ink, highlighter-yellow accents. */
:root {
  --bg: #f1f4ee; --paper: #fbfcf9; --grid: rgba(47,107,79,.07); --fg: #1b231e; --muted: #56625a; --line: #d5ddd3;
  --accent: #2f6b4f; --accent-ink: #ffffff; --hl: #f6dc6a; --hl-ink: #3b3200; --warn: #fdf1c7; --warn-ink: #5a4500;
  --mock: #a03d2c; --review: #3c5a8a; --sat: #7a5a12;
  --display: "Archivo", "Arial Narrow", system-ui, sans-serif;
  --body: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, Consolas, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) { :root {
  --bg: #111613; --paper: #171d19; --grid: rgba(127,196,160,.06); --fg: #e2e8e2; --muted: #9aa79e; --line: #2b352f;
  --accent: #7fc4a0; --accent-ink: #0f1a14; --hl: #6b5a12; --hl-ink: #fbefb8; --warn: #3a3214; --warn-ink: #f3e3a6;
  --mock: #e49a8a; --review: #9db8e8; --sat: #e0c06a; color-scheme: dark;
} }
* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg); color: var(--fg); font: 16px/1.55 var(--body);
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 22px 22px; -webkit-text-size-adjust: 100%;
}
h1, h2, h3, h4 { font-family: var(--display); margin: 0; text-wrap: balance; letter-spacing: -.01em; }
h1 { font-size: clamp(1.7rem, 4vw, 2.4rem); font-weight: 800; }
h2 { font-size: 1.25rem; }
h4 { font-size: .78rem; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); margin: 14px 0 6px; }
a { color: var(--accent); }
.wrap, .auth { max-width: 880px; margin: 0 auto; padding: 24px max(16px, env(safe-area-inset-right)) 64px max(16px, env(safe-area-inset-left)); display: grid; gap: 18px; }
.auth { max-width: 520px; padding-top: 10vh; }
.auth h1 em { font-style: normal; display: block; color: var(--accent); }
.lede { color: var(--muted); margin: 0; }
.loading { text-align: center; padding: 30vh 16px; color: var(--muted); }

.top { position: sticky; top: 0; z-index: 5; background: var(--paper); border-bottom: 1px solid var(--line); padding-top: env(safe-area-inset-top); }
.bar { max-width: 880px; margin: 0 auto; padding: 10px max(16px, env(safe-area-inset-right)) 10px max(16px, env(safe-area-inset-left)); display: flex; flex-wrap: wrap; align-items: center; gap: 8px 18px; }
.brand { font: 700 1.15rem var(--display); }
.brand b { color: var(--accent); }
nav { display: flex; gap: 4px; flex-wrap: wrap; }
nav button { border: 0; background: none; padding: 6px 10px; font: 500 .95rem var(--body); color: var(--muted); border-radius: 6px; cursor: pointer; }
nav button[aria-current="true"] { background: var(--accent); color: var(--accent-ink); }
.who { margin-left: auto; font-size: .85rem; color: var(--muted); display: flex; gap: 8px; align-items: center; min-width: 0; overflow-wrap: anywhere; }
.demo { margin: 0; background: var(--warn); color: var(--warn-ink); padding: 8px 16px; font-size: .88rem; text-align: center; }

.card { background: var(--paper); border: 1px solid var(--line); border-radius: 10px; padding: 18px; display: grid; gap: 10px; min-width: 0; }
.card.quiet { color: var(--muted); }
.stack { display: grid; gap: 18px; }
.grid2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 14px; }
.row { display: flex; gap: 10px; align-items: center; }
.row.wraps { flex-wrap: wrap; }
.hint, .msg { margin: 0; color: var(--muted); font-size: .92rem; }
.msg:empty { display: none; }
.opt { font: 500 .75rem var(--mono); color: var(--muted); text-transform: uppercase; margin-left: 6px; }
.warn { margin: 0; background: var(--warn); color: var(--warn-ink); padding: 10px 14px; border-radius: 8px; }
.note { margin: 6px 0 0; font-size: .9rem; color: var(--muted); border-left: 3px solid var(--line); padding-left: 10px; }

label { font-weight: 600; font-size: .9rem; }
input[type=email], input[type=password], input[type=date], input[type=time] {
  width: 100%; font: 16px var(--body); padding: 10px 12px; border: 1px solid var(--line); border-radius: 8px; background: var(--bg); color: var(--fg);
}
form.card { gap: 8px; }
form.card input { margin-bottom: 6px; }
button, .button {
  font: 600 .95rem var(--body); padding: 10px 16px; border-radius: 8px; border: 1px solid var(--line); background: var(--paper); color: var(--fg); cursor: pointer; display: inline-block;
}
button:hover:not(:disabled), .button:hover { border-color: var(--accent); }
button:disabled { opacity: .45; cursor: not-allowed; }
button.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
button.big { font-size: 1.05rem; padding: 14px; }
button.link { border: 0; background: none; padding: 0; color: var(--accent); text-decoration: underline; font-weight: 500; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.chk { display: inline-flex; gap: 8px; align-items: center; font-weight: 600; cursor: pointer; }
.chk.big { font-size: 1rem; padding-top: 6px; }
.chk input { width: 20px; height: 20px; accent-color: var(--accent); }

.sources { list-style: none; margin: 0; padding: 0; border: 1px solid var(--line); border-radius: 8px; }
.sources li { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 12px; padding: 8px 12px; border-top: 1px solid var(--line); }
.sources li:first-child { border-top: 0; }
.sources .src { font-weight: 600; overflow-wrap: anywhere; }
.sources .cnt { font: .8rem var(--mono); color: var(--muted); }
.sources button { margin-left: auto; }
.tw { overflow-x: auto; }
.avail { border-collapse: collapse; width: 100%; min-width: 520px; }
.avail th { text-align: left; font: 500 .75rem var(--mono); color: var(--muted); text-transform: uppercase; padding: 4px 6px; }
.avail td { padding: 4px 6px; }
.avail input[type=time] { padding: 6px 8px; }

.hero { display: grid; gap: 14px; }
.count b { font: 800 clamp(3rem, 12vw, 5rem)/1 var(--display); color: var(--accent); display: block; }
.count span { color: var(--muted); }
.stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: 10px; overflow: hidden; }
.stats div { background: var(--paper); padding: 10px 12px; }
.stats b { display: block; font: 700 1.4rem var(--display); font-variant-numeric: tabular-nums; }
.stats span { font-size: .8rem; color: var(--muted); }

.eyebrow { margin: 0; font: 500 .78rem var(--mono); color: var(--muted); text-transform: uppercase; letter-spacing: .04em; }
.session { border-left: 5px solid var(--accent); }
.k-mock { border-left-color: var(--mock); }
.k-review, .k-light { border-left-color: var(--review); }
.k-block { border-left-color: var(--sat); }
.unit { border-top: 1px solid var(--line); padding-top: 10px; }
.unit h4 { color: var(--fg); text-transform: none; letter-spacing: 0; font-size: 1.02rem; margin: 0 0 4px; }
.unit .min { font: 500 .75rem var(--mono); color: var(--muted); margin-left: 6px; }
.unit ul, .card ul, .card ol { margin: 4px 0; padding-left: 20px; }
.meta { margin: 6px 0; font-size: .9rem; }
.calc { width: 100%; border-collapse: collapse; font-size: .88rem; margin: 6px 0; }
.calc td { padding: 5px 6px; border-bottom: 1px solid var(--line); vertical-align: top; }
.calc .key { font-family: var(--mono); font-size: .82rem; color: var(--accent); }
.calc .pg { font-family: var(--mono); font-size: .82rem; white-space: nowrap; text-align: right; }
.vids { display: grid; gap: 8px; margin-top: 8px; }
.vid { display: grid; grid-template-columns: 168px minmax(0, 1fr); gap: 12px; align-items: center; padding: 8px; border: 1px solid var(--line); border-radius: 10px; background: var(--bg); }
.vid.playing { grid-template-columns: 1fr; }
.thumb { position: relative; padding: 0; border: 0; border-radius: 6px; overflow: hidden; aspect-ratio: 16 / 9; background: #000; cursor: pointer; }
.thumb img { width: 100%; height: 100%; object-fit: cover; display: block; }
.thumb .play { position: absolute; inset: 50% auto auto 50%; transform: translate(-50%, -50%); width: 42px; height: 30px; border-radius: 8px; background: rgba(204, 0, 0, .9); color: #fff; display: grid; place-items: center; font-size: .9rem; }
.thumb .len { position: absolute; right: 4px; bottom: 4px; background: rgba(0, 0, 0, .8); color: #fff; font: .7rem var(--mono); padding: 1px 4px; border-radius: 3px; }
.thumb:hover .play { background: #c00; }
.vmeta { display: grid; gap: 2px; min-width: 0; }
.vmeta b { font-weight: 600; font-size: .92rem; line-height: 1.3; }
.vmeta small { font: .74rem var(--mono); color: var(--muted); }
.vmeta a { font-size: .82rem; }
.player { width: 100%; aspect-ratio: 16 / 9; border: 0; border-radius: 6px; background: #000; }
@media (max-width: 480px) { .vid { grid-template-columns: 120px minmax(0, 1fr); } }
.plthumb { background: linear-gradient(135deg, var(--accent), color-mix(in srgb, var(--accent) 55%, #000)); }
.plthumb .stackico { position: absolute; left: 8px; top: 4px; color: #fff; font-size: 1.4rem; opacity: .85; }
.vid.pl { border-color: var(--accent); }

/* Advice from people who passed */
.tips { margin-top: 8px; background: color-mix(in srgb, var(--hl) 30%, var(--paper)); border-radius: 8px; padding: 10px 14px; font-size: .92rem; }
.tips b { font: 600 .74rem var(--mono); text-transform: uppercase; letter-spacing: .05em; }
.tips ul { margin: 4px 0 0; padding-left: 18px; }
.tipl { margin: 0; display: grid; gap: 0; }
.tipl div { padding: 10px 0; border-top: 1px solid var(--line); }
.tipl div:first-child { border-top: 0; padding-top: 0; }
.tipl dt { font-weight: 600; }
.tipl dd { margin: 2px 0 0; color: var(--muted); font-size: .94rem; }

.week h3 { display: flex; justify-content: space-between; border-bottom: 2px solid var(--fg); padding: 6px 0; font-size: 1rem; }
.week h3 span { font: 500 .8rem var(--mono); color: var(--accent); }
.plan-row { display: grid; grid-template-columns: 28px minmax(0, 1fr); gap: 8px; padding: 8px 0; border-bottom: 1px solid var(--line); align-items: start; }
.plan-row input { width: 20px; height: 20px; margin-top: 3px; accent-color: var(--accent); }
.plan-row.is-today { background: color-mix(in srgb, var(--hl) 35%, transparent); }
.plan-row.is-done .ttl { text-decoration: line-through; color: var(--muted); }
.plan-row summary { cursor: pointer; display: flex; flex-wrap: wrap; gap: 4px 8px; align-items: baseline; list-style: none; }
.plan-row summary::-webkit-details-marker { display: none; }
.when { font: 500 .82rem var(--mono); color: var(--muted); }
.ttl { flex-basis: 100%; font-weight: 600; }
.pill { font: 600 .66rem/1 var(--mono); text-transform: uppercase; letter-spacing: .05em; padding: 3px 6px; border: 1px solid currentColor; border-radius: 4px; color: var(--accent); }
.p-mock { color: var(--mock); } .p-review, .p-light { color: var(--review); } .p-block { color: var(--sat); }
.p-exam { background: var(--accent); color: var(--accent-ink); }
.body { padding: 8px 0; }
.topic summary { display: flex; flex-wrap: wrap; gap: 8px; align-items: baseline; cursor: pointer; list-style: none; }
.topic summary::-webkit-details-marker { display: none; }
.q { font: 500 .78rem var(--mono); background: var(--hl); color: var(--hl-ink); padding: 2px 6px; border-radius: 4px; }

/* Landing page (signed out) */
.landing { max-width: 1080px; margin: 0 auto; padding: 0 max(16px, env(safe-area-inset-right)) 48px max(16px, env(safe-area-inset-left)); display: grid; gap: 56px; }
.lbar { display: flex; justify-content: space-between; align-items: center; padding-top: max(14px, env(safe-area-inset-top)); }
.button.small { padding: 6px 12px; font-size: .88rem; text-decoration: none; }
a.button { text-decoration: none; text-align: center; }
a.button.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.lhero { display: grid; grid-template-columns: minmax(0, 1.3fr) minmax(280px, 1fr); gap: 40px; align-items: start; }
.lcopy { display: grid; gap: 18px; }
.lhero h1 { font-size: clamp(2rem, 5vw, 3.3rem); line-height: 1.05; }
.lhero h1 em { font-style: normal; color: var(--accent); display: block; }
.steps { margin: 0; padding-left: 22px; display: grid; gap: 6px; }
.lform { gap: 8px; box-shadow: 0 10px 30px -18px rgba(0, 0, 0, .35); }
.lform h2 { margin-bottom: 4px; }
.lsec { display: grid; gap: 16px; }
.lsec > h2 { font-size: clamp(1.5rem, 3vw, 2rem); }
.pillars { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 12px; }
@media (max-width: 960px) { .pillars { grid-template-columns: repeat(2, minmax(0, 1fr)); } .pillar:last-child { grid-column: 1 / -1; } }
@media (max-width: 520px) { .pillars { grid-template-columns: 1fr; } }
.lform #forgot { justify-self: start; }
.who h2 { font-size: clamp(1.5rem, 3vw, 2rem); margin-bottom: 12px; }
.pillar { background: var(--paper); border: 1px solid var(--line); border-top: 4px solid var(--accent); border-radius: 10px; padding: 16px; display: grid; gap: 6px; align-content: start; }
.pillar .num { font: 600 .78rem var(--mono); color: var(--muted); }
.pillar h3 { font-size: 1.1rem; }
.pillar p { margin: 0; font-size: .93rem; color: var(--muted); }
.pillar:nth-child(4) { border-top-color: var(--hl); }
.who { grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr); gap: 32px; align-items: center; }
.who p { margin: 0 0 12px; }
.who blockquote { margin: 0; padding: 22px; background: var(--hl); color: var(--hl-ink); border-radius: 10px; font: 600 1.25rem/1.35 var(--display); }
.who cite { display: block; margin-top: 10px; font: 400 .82rem var(--mono); font-style: normal; }
.inside { margin: 0; padding: 0; list-style: none; display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 10px 24px; }
.inside li { padding-left: 22px; position: relative; }
.inside li::before { content: "✓"; position: absolute; left: 0; color: var(--accent); font-weight: 700; }
.lsec .button.big { justify-self: start; padding: 14px 22px; }
.lfoot { border-top: 1px solid var(--line); padding-top: 16px; font-size: .85rem; color: var(--muted); }
@media (max-width: 760px) {
  .lhero, .who { grid-template-columns: 1fr; }
  .landing { gap: 40px; }
}

/* Resources tab */
.reslist { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 14px; }
.res { align-content: start; border-top: 4px solid var(--accent); }
.res p { margin: 0; color: var(--muted); font-size: .94rem; }
.reshead { display: flex; flex-wrap: wrap; gap: 8px; align-items: baseline; justify-content: space-between; }
.res .button { justify-self: start; margin-top: 4px; }

/* Paywall and pricing */
.paywall { border: 2px solid var(--accent); }
.price { display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; }
.price b { font: 800 2.6rem/1 var(--display); color: var(--accent); }
.price span { color: var(--muted); font-size: .92rem; }
.paywall .button.big, .paywall button.big { justify-self: start; padding: 14px 22px; }
.locked { margin: 8px 0 0; font-size: .9rem; color: var(--muted); background: var(--bg); border: 1px dashed var(--line); border-radius: 8px; padding: 8px 12px; }
.pricing { grid-template-columns: minmax(0, 1fr) minmax(280px, 380px); gap: 32px; align-items: start; }
.pricecard { border-top: 4px solid var(--accent); }
.trialbar { background: color-mix(in srgb, var(--hl) 30%, var(--paper)); gap: 6px; }
.trialbar p { margin: 0; }
.pricecard .inside { grid-template-columns: 1fr; }
.pricecard .button.big { justify-self: stretch; }
@media (max-width: 760px) { .pricing { grid-template-columns: 1fr; } }

#toast { position: fixed; left: 50%; bottom: max(20px, env(safe-area-inset-bottom)); transform: translateX(-50%); background: var(--fg); color: var(--bg); padding: 10px 16px; border-radius: 8px; max-width: calc(100% - 32px); z-index: 10; }
@media (max-width: 560px) { .stats b { font-size: 1.15rem; } .who { margin-left: 0; } }