:root {
  --bg: #FFFFFF;
  --surface: #FFFFFF;
  --text: #0A0A0A;
  --muted: #6E6E6E;
  --faint: #767676;
  --border: #E6E6E6;
  --border-strong: #0A0A0A;
  --hover: #F5F5F5;
  --ink: #0A0A0A;
  --on-ink: #FFFFFF;
  --radius: 14px;
  --serif: "Instrument Serif", Georgia, "Times New Roman", serif;
  --sans: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  --ease: cubic-bezier(.2, .7, .2, 1);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #000000;
    --surface: #0A0A0A;
    --text: #F5F5F5;
    --muted: #8F8F8F;
    --faint: #7A7A7A;
    --border: #1F1F1F;
    --border-strong: #F5F5F5;
    --hover: #111111;
    --ink: #F5F5F5;
    --on-ink: #000000;
  }
}

:root[data-theme="dark"] {
  --bg: #000000;
  --surface: #0A0A0A;
  --text: #F5F5F5;
  --muted: #8F8F8F;
  --faint: #7A7A7A;
  --border: #1F1F1F;
  --border-strong: #F5F5F5;
  --hover: #111111;
  --ink: #F5F5F5;
  --on-ink: #000000;
}

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-behavior: smooth; scroll-padding-top: 72px; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
h1, h2 { font-family: var(--serif); font-weight: 400; line-height: 1.05; margin: 0 0 .45em; letter-spacing: -.01em; }
h1 { font-size: clamp(2.8rem, 8vw, 5.6rem); }
h2 { font-size: clamp(2rem, 5vw, 3.2rem); }
h3 { font-size: 1rem; font-weight: 600; margin: 0 0 .4em; }
p { margin: 0 0 1em; }
a { color: inherit; }
em { font-style: italic; }
::selection { background: var(--ink); color: var(--on-ink); }

.container { width: 100%; max-width: 1080px; margin: 0 auto; padding: 0 16px; }
@media (min-width: 640px) { .container { padding: 0 32px; } }
.narrow { max-width: 720px; }
.center { text-align: center; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* Buttons */
.btn {
  position: relative; display: inline-flex; align-items: center; justify-content: center;
  gap: .5em; padding: .8em 1.5em; border-radius: 999px;
  font: 500 .95rem var(--sans); text-decoration: none; cursor: pointer;
  border: 1px solid var(--border-strong);
  transition: background .2s var(--ease), color .2s var(--ease), transform .2s var(--ease), opacity .2s;
}
.btn:active:not(:disabled) { transform: scale(.97); }
.btn:disabled { opacity: .3; cursor: not-allowed; }
.btn-primary { background: var(--ink); color: var(--on-ink); }
.btn-primary:hover:not(:disabled) { background: transparent; color: var(--text); }
.btn-ghost { background: transparent; color: var(--text); }
.btn-ghost:hover { background: var(--ink); color: var(--on-ink); }
.btn-sm { padding: .5em 1.1em; font-size: .85rem; }
.arrow { transition: transform .2s var(--ease); }
.btn:hover .arrow { transform: translateX(3px); }

/* Nav */
.nav {
  position: sticky; top: 0; z-index: 10;
  background: color-mix(in srgb, var(--bg) 80%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color .2s;
}
.nav.scrolled { border-bottom-color: var(--border); }
.nav-inner { display: flex; align-items: center; gap: 28px; height: 64px; }
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; }
.logo {
  display: grid; place-items: center; width: 32px; height: 32px; border-radius: 8px;
  background: var(--ink); color: var(--on-ink);
  font: 400 1.5rem/1 var(--serif);
  padding-bottom: .375em; /* optically centres the φ glyph, which sits low in its line box */
  transition: transform .5s var(--ease);
}
.brand:hover .logo { transform: rotate(-12deg); }
.wordmark { font: 600 1.05rem var(--sans); letter-spacing: -.02em; }
.nav-links { display: flex; gap: 28px; margin-left: auto; }
.nav-links a {
  position: relative; text-decoration: none; color: var(--muted); font-size: .9rem;
  transition: color .2s;
}
.nav-links a::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: -4px; height: 1px;
  background: var(--text); transform: scaleX(0); transform-origin: left; transition: transform .25s var(--ease);
}
.nav-links a:hover { color: var(--text); }
.nav-links a:hover::after { transform: scaleX(1); }
.nav-toggle { display: none; }

@media (max-width: 760px) {
  .nav-cta { display: none; }
  .nav-toggle {
    display: grid; gap: 6px; margin-left: auto; padding: 10px;
    background: none; border: 0; cursor: pointer;
  }
  .nav-toggle span { display: block; width: 20px; height: 1.5px; background: var(--text); transition: transform .25s var(--ease); }
  .nav-toggle[aria-expanded="true"] span:first-child { transform: translateY(3.75px) rotate(45deg); }
  .nav-toggle[aria-expanded="true"] span:last-child { transform: translateY(-3.75px) rotate(-45deg); }
  .nav-links {
    position: absolute; top: 64px; left: 0; right: 0;
    flex-direction: column; gap: 0; margin: 0;
    background: var(--bg); border-bottom: 1px solid var(--border);
    display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 16px; border-top: 1px solid var(--border); color: var(--text); }
  .nav-links a::after { display: none; }
}

/* Hero */
.hero {
  position: relative; overflow: hidden; min-height: calc(100vh - 64px);
  display: flex; align-items: center; padding: 72px 0 96px;
}
.hero::after { /* keeps the text readable over the field */
  content: ""; position: absolute; inset: 0; pointer-events: none;
  background: radial-gradient(ellipse 60% 55% at 50% 48%, color-mix(in srgb, var(--bg) 88%, transparent) 0%, color-mix(in srgb, var(--bg) 55%, transparent) 55%, transparent 100%);
}
.hero-inner { position: relative; z-index: 1; pointer-events: none; }
.hero-inner a, .hero-inner button { pointer-events: auto; }
.field { position: absolute; inset: 0; width: 100%; height: 100%; display: block; cursor: crosshair; }
.hero h1 {
  font: 800 clamp(2.6rem, 7vw, 5.4rem)/1.02 var(--sans); letter-spacing: -.045em;
  margin: 0 auto .4em; max-width: 900px;
}
.hero .lede { max-width: 620px; font-size: 1.12rem; }
.lede strong { color: var(--text); font-weight: 600; }
.hero .hero-ctas { justify-content: center; margin: 36px 0 56px; }
.pill {
  display: inline-flex; align-items: center; gap: 10px; margin-bottom: 28px;
  padding: .45em 1em; border: 1px solid var(--border); border-radius: 999px;
  background: color-mix(in srgb, var(--bg) 70%, transparent); backdrop-filter: blur(6px);
  font-size: .85rem; color: var(--muted); text-decoration: none; transition: border-color .2s, color .2s;
}
.pill:hover { border-color: var(--border-strong); color: var(--text); }
.pill:hover .arrow { transform: translateX(3px); }
.live-dot {
  width: 7px; height: 7px; border-radius: 50%; background: var(--text); flex: none;
  box-shadow: 0 0 0 0 color-mix(in srgb, var(--text) 60%, transparent); animation: pulse 2s infinite;
}
@keyframes pulse { 70% { box-shadow: 0 0 0 7px transparent; } 100% { box-shadow: 0 0 0 0 transparent; } }
.stats-label {
  display: inline-flex; align-items: center; gap: 8px; margin: 0 0 14px;
  font: 500 .72rem ui-monospace, "SFMono-Regular", Consolas, monospace; letter-spacing: .18em; text-transform: uppercase; color: var(--muted);
}
.stats-row { display: flex; justify-content: center; gap: clamp(28px, 7vw, 72px); flex-wrap: wrap; }
.stat { display: flex; flex-direction: column; align-items: center; gap: 4px; }
.stat-num { font: 700 clamp(1.8rem, 4vw, 2.4rem)/1 ui-monospace, "SFMono-Regular", Consolas, monospace; letter-spacing: -.02em; font-variant-numeric: tabular-nums; }
.stat-label { font-size: .8rem; color: var(--muted); }
.field-hint {
  position: absolute; left: 50%; bottom: 20px; transform: translateX(-50%); z-index: 1; margin: 0;
  font: 500 .7rem ui-monospace, "SFMono-Regular", Consolas, monospace; letter-spacing: .14em; text-transform: uppercase;
  color: var(--faint); pointer-events: none; white-space: nowrap;
}
@media (hover: none) { .field-hint { display: none; } }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: .78rem; font-weight: 500; text-transform: uppercase; letter-spacing: .16em;
  color: var(--muted); margin-bottom: 1.2em;
}
.eyebrow::before { content: ""; width: 18px; height: 1px; background: currentColor; }
.center .eyebrow::before { display: none; }
.lede { font-size: 1.1rem; color: var(--muted); max-width: 520px; }
.center .lede { margin-left: auto; margin-right: auto; }
.hero-ctas { display: flex; flex-wrap: wrap; gap: 12px; margin: 32px 0 40px; }

/* Sections */
.section { padding: 112px 0; border-top: 1px solid var(--border); }
.note { color: var(--muted); font-size: .9rem; margin-top: 16px; }

/* Question card */
.q-card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 32px; margin-top: 32px;
  transition: border-color .3s;
}
.q-card:hover { border-color: var(--faint); }
@media (max-width: 480px) { .q-card { padding: 20px; } }
.q-meta { display: flex; gap: 16px; margin-bottom: 20px; font-size: .78rem; color: var(--muted); text-transform: uppercase; letter-spacing: .12em; }
.q-text { font-size: 1.15rem; }
.options { display: grid; gap: 8px; margin: 24px 0; }
.option {
  display: flex; align-items: center; gap: 14px; width: 100%; text-align: left;
  padding: 12px 16px; border-radius: 10px; cursor: pointer;
  background: transparent; color: var(--text); border: 1px solid var(--border);
  font: 400 1rem var(--sans);
  transition: border-color .2s, background .2s, transform .2s var(--ease);
}
.option:hover:not(:disabled) { border-color: var(--border-strong); transform: translateX(4px); }
.option .key {
  display: grid; place-items: center; width: 26px; height: 26px; flex: none;
  border-radius: 6px; border: 1px solid var(--border); font-size: .8rem; font-weight: 500; color: var(--muted);
  transition: background .2s, color .2s, border-color .2s;
}
.option .mark { margin-left: auto; font-size: .85rem; font-weight: 500; }
.option[aria-checked="true"] { border-color: var(--border-strong); }
.option[aria-checked="true"] .key { background: var(--ink); color: var(--on-ink); border-color: var(--ink); }
.option.correct { background: var(--ink); color: var(--on-ink); border-color: var(--ink); }
.option.correct .key { background: var(--on-ink); color: var(--ink); border-color: var(--on-ink); }
.option.wrong { border-style: dashed; border-color: var(--border-strong); color: var(--muted); }
.option.wrong .val { text-decoration: line-through; }
.option.dim { opacity: .4; }
.option:disabled { cursor: default; }
.q-actions { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.kbd-hint { font-size: .8rem; color: var(--faint); margin-left: auto; }
kbd {
  font: 500 .75rem var(--sans); padding: .1em .45em; border: 1px solid var(--border);
  border-radius: 4px; color: var(--muted);
}
@media (hover: none) { .kbd-hint { display: none; } }
.feedback { font-weight: 500; margin-top: 18px; min-height: 1.6em; }
.solution {
  display: grid; grid-template-rows: 0fr; transition: grid-template-rows .5s var(--ease);
}
.solution.open { grid-template-rows: 1fr; }
.solution-inner { overflow: hidden; }
.solution-body { border-top: 1px solid var(--border); margin-top: 16px; padding-top: 20px; }
.solution .tip { color: var(--muted); font-size: .95rem; font-style: italic; }

/* Feature grid */
.grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  margin-top: 40px; border-top: 1px solid var(--border); border-left: 1px solid var(--border);
}
.card {
  padding: 32px 28px; border-right: 1px solid var(--border); border-bottom: 1px solid var(--border);
  transition: background .3s var(--ease), color .3s var(--ease);
}
.card p { color: var(--muted); margin: 0; font-size: .95rem; transition: color .3s; }
.card:hover { background: var(--ink); color: var(--on-ink); }
.card:hover p { color: color-mix(in srgb, var(--on-ink) 70%, transparent); }
.icon { font: 400 2.2rem/1 var(--serif); margin-bottom: 28px; transition: transform .4s var(--ease); display: inline-block; }
.card:hover .icon { transform: scale(1.15) rotate(-6deg); }

/* Steps */
.steps { list-style: none; padding: 0; margin: 40px 0 0; display: grid; gap: 32px; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.steps li { border-top: 1px solid var(--border-strong); padding-top: 20px; }
.steps p { color: var(--muted); margin: 0; }
.num { display: block; font: 400 2.6rem/1 var(--serif); margin-bottom: 16px; }

/* Pricing */
.pricing { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); max-width: 720px; margin: 40px auto 0; }
.plan {
  position: relative; border: 1px solid var(--border); border-radius: var(--radius); padding: 32px;
  display: flex; flex-direction: column;
  transition: transform .3s var(--ease), border-color .3s;
}
.plan:hover { transform: translateY(-4px); border-color: var(--border-strong); }
.plan.featured { background: var(--ink); color: var(--on-ink); border-color: var(--ink); }
.plan.featured ul { color: color-mix(in srgb, var(--on-ink) 70%, transparent); }
.plan.featured .btn-primary { background: var(--on-ink); color: var(--ink); border-color: var(--on-ink); }
.plan.featured .btn-primary:hover { background: transparent; color: var(--on-ink); }
.plan ul { list-style: none; padding: 0; color: var(--muted); margin: 0 0 28px; flex: 1; }
.plan li { padding: .45em 0; border-bottom: 1px solid color-mix(in srgb, currentColor 18%, transparent); }
.price { font: 400 2.6rem/1.1 var(--serif); margin-bottom: .6em; }
.badge {
  position: absolute; top: 24px; right: 24px; font-size: .7rem; text-transform: uppercase; letter-spacing: .14em;
  border: 1px solid currentColor; padding: .25em .7em; border-radius: 999px;
}

.btn.is-static { cursor: default; }
.btn.is-static:active { transform: none; }
.small a { color: inherit; }
.legal { border-top: 0; padding-top: 64px; }
.legal h1 { font-size: clamp(2.4rem, 6vw, 3.6rem); }
.legal h3 { margin-top: 2em; }
.legal p { color: var(--muted); }

/* FAQ */
details { border-bottom: 1px solid var(--border); }
details:first-of-type { border-top: 1px solid var(--border); margin-top: 32px; }
summary {
  cursor: pointer; font-weight: 500; list-style: none; padding: 22px 0;
  display: flex; justify-content: space-between; align-items: center; gap: 16px;
}
summary::-webkit-details-marker { display: none; }
summary::after {
  content: "+"; font: 300 1.5rem/1 var(--sans); transition: transform .3s var(--ease);
}
details[open] summary::after { transform: rotate(45deg); }
details p { color: var(--muted); margin: 0 0 22px; max-width: 600px; }

/* Footer */
.footer { border-top: 1px solid var(--border); padding: 40px 0; }
.footer-inner { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 16px; }
.small { font-size: .82rem; color: var(--muted); margin: 0; }

:focus-visible { outline: 1.5px solid var(--text); outline-offset: 3px; }

/* Scroll reveal */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity .8s var(--ease), transform .8s var(--ease); }
.reveal.in { opacity: 1; transform: none; }
.no-js .reveal { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; animation: none !important; }
  .reveal { opacity: 1; transform: none; }
}.plan.featured .btn.is-static:hover { background: var(--on-ink); color: var(--ink); }

/* Practice */
.practice { padding: 28px 0 56px; }
.practice-head { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.practice-title { font-size: clamp(2.2rem, 6vw, 3.2rem); margin: 0; }
.progress-line { margin: 0; font-size: .85rem; color: var(--muted); }
.controls { margin-top: 18px; display: grid; gap: 12px; }
.chips-scroll { display: flex; flex-wrap: wrap; gap: 8px; }
@media (max-width: 760px) {
  .chips-scroll {
    flex-wrap: nowrap; overflow-x: auto; scrollbar-width: none; margin: 0 -16px; padding: 2px 16px;
    -webkit-mask-image: linear-gradient(90deg, transparent, #000 16px, #000 calc(100% - 24px), transparent);
            mask-image: linear-gradient(90deg, transparent, #000 16px, #000 calc(100% - 24px), transparent);
  }
  .chips-scroll::-webkit-scrollbar { display: none; }
}
.chip {
  flex: none; font: 500 .85rem var(--sans); padding: .45em 1em; border-radius: 999px; cursor: pointer;
  border: 1px solid var(--border); background: transparent; color: var(--muted);
  transition: border-color .2s, color .2s, background .2s;
}
.chip:hover { border-color: var(--border-strong); color: var(--text); }
.chip.active { background: var(--ink); color: var(--on-ink); border-color: var(--ink); }
.controls-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.segmented { display: inline-flex; border: 1px solid var(--border); border-radius: 999px; padding: 3px; gap: 2px; max-width: 100%; overflow-x: auto; scrollbar-width: none; }
.segmented::-webkit-scrollbar { display: none; }
.seg {
  flex: none; font: 500 .8rem var(--sans); padding: .4em .85em; border: 0; border-radius: 999px; cursor: pointer;
  background: transparent; color: var(--muted); transition: background .2s, color .2s;
}
.seg:hover { color: var(--text); }
.seg.active { background: var(--ink); color: var(--on-ink); }
.switch { display: inline-flex; align-items: center; gap: 8px; font-size: .85rem; color: var(--muted); cursor: pointer; user-select: none; }
.switch input { position: absolute; opacity: 0; width: 1px; height: 1px; }
.switch-track { width: 34px; height: 20px; border-radius: 999px; border: 1px solid var(--border-strong); position: relative; transition: background .2s; }
.switch-track::after {
  content: ""; position: absolute; top: 2px; left: 2px; width: 14px; height: 14px; border-radius: 50%;
  background: var(--text); transition: transform .2s var(--ease), background .2s;
}
.switch input:checked + .switch-track { background: var(--ink); }
.switch input:checked + .switch-track::after { transform: translateX(14px); background: var(--on-ink); }
.switch input:focus-visible + .switch-track { outline: 1.5px solid var(--text); outline-offset: 3px; }
.practice .q-card { margin-top: 18px; }
.q-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; margin-bottom: 18px; }
.q-top .q-meta { margin: 0; flex-wrap: wrap; row-gap: 4px; }
.q-meta span { white-space: nowrap; }
.timer {
  flex: none; font: 600 .8rem ui-monospace, "SFMono-Regular", Consolas, monospace; font-variant-numeric: tabular-nums;
  border: 1px solid var(--border); border-radius: 999px; padding: .3em .8em; color: var(--muted);
}
.timer.over { color: var(--on-ink); background: var(--ink); border-color: var(--ink); }
.action-bar { display: flex; align-items: center; justify-content: flex-end; gap: 12px; margin-top: 16px; }
.action-bar .kbd-hint { margin-right: auto; margin-left: 0; }
@media (max-width: 760px) {
  .action-bar {
    position: sticky; bottom: 0; z-index: 5; margin: 16px -16px 0;
    padding: 12px 16px calc(12px + env(safe-area-inset-bottom));
    background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(12px);
    border-top: 1px solid var(--border);
  }
  .action-bar .btn { width: 100%; }
}
.score {
  font: 500 .9rem ui-monospace, "SFMono-Regular", Consolas, monospace;
  border: 1px solid var(--border); border-radius: 999px; padding: .35em .9em;
}
.nav-inner .score { margin-left: 0; }
.install-btn { margin-left: auto; }
.install-btn[hidden] + .score { margin-left: auto; }
.trap {
  margin-top: 12px; padding: 14px 16px; border-left: 2px solid var(--border-strong);
  background: var(--hover); border-radius: 0 10px 10px 0; color: var(--text); font-size: .95rem;
}
.link-btn { background: none; border: 0; padding: 0; color: var(--muted); font: inherit; text-decoration: underline; cursor: pointer; }
.link-btn:hover { color: var(--text); }
.link-btn[hidden] { display: none; }
.ios-tip {
  position: fixed; left: 16px; right: 16px; bottom: calc(16px + env(safe-area-inset-bottom)); z-index: 20;
  max-width: 420px; margin: 0 auto; padding: 16px; border-radius: var(--radius);
  background: var(--surface); border: 1px solid var(--border-strong); display: flex; gap: 12px; align-items: center;
}
.ios-tip p { margin: 0; font-size: .9rem; }
/* Hero entrance: CSS-only so it never waits for scripts */
.rise { animation: rise .9s var(--ease) both; }
.r1 { animation-delay: .05s; } .r2 { animation-delay: .15s; } .r3 { animation-delay: .25s; }
.r4 { animation-delay: .35s; } .r5 { animation-delay: .45s; }
@keyframes rise { from { opacity: 0; transform: translateY(18px); } to { opacity: 1; transform: none; } }.nav-links + .install-btn { margin-left: 0; }