:root {
  --ink: #0E1B2A;
  --ink-2: #17293B;
  --text: #33424F;
  --muted: #4A5966;
  --line: #D5DEDB;
  --ground: #F5F8F7;
  --white: #FFFFFF;
  --accent: #0B6E5A;
  --accent-dark: #084F41;
  --tint: #E3F0EC;
  --yellow: #FFD23F;
  --on-dark: #E8EEF2;
  --on-dark-muted: #C3CFD8;
  --error: #A12622;
  --display: 'Bricolage Grotesque', system-ui, sans-serif;
  --body: 'IBM Plex Sans', system-ui, sans-serif;
  --mono: 'IBM Plex Mono', ui-monospace, monospace;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--ground); color: var(--ink); font-family: var(--body); font-size: 17px; line-height: 1.55; }
a { color: var(--accent); }
a:hover { color: var(--accent-dark); }
img, svg { max-width: 100%; }
h1, h2, h3 { font-family: var(--display); font-weight: 700; margin: 0; letter-spacing: -0.01em; }
h1 { font-size: clamp(36px, 5.2vw, 60px); line-height: 1.05; letter-spacing: -0.02em; }
h2 { font-size: clamp(28px, 3.6vw, 40px); line-height: 1.12; }
h3 { font-size: 22px; line-height: 1.2; }
p { margin: 0; }
.wrap { max-width: 1120px; margin: 0 auto; padding: 0 24px; }
.narrow { max-width: 720px; }
.section { padding: 72px 0; }
.section-sm { padding: 48px 0; }
.stack { display: flex; flex-direction: column; gap: 20px; }
.stack-lg { display: flex; flex-direction: column; gap: 36px; }
.row { display: flex; flex-wrap: wrap; gap: 20px; }
.row > * { flex: 1 1 280px; min-width: 0; }
.split { display: flex; flex-wrap: wrap; gap: 48px; align-items: center; }
.split > * { flex: 1 1 380px; min-width: 0; }
.eyebrow { font-family: var(--mono); font-size: 14px; letter-spacing: 0.06em; text-transform: uppercase; color: var(--accent); }
.lead { font-size: 20px; color: var(--text); max-width: 620px; }
.muted { color: var(--muted); }
.small { font-size: 15px; }
.mark { background: var(--yellow); padding: 0 8px; border-radius: 6px; }

/* Header */
.site-header { background: var(--ground); border-bottom: 1px solid var(--line); }
.site-header .wrap { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 8px 20px; padding-top: 12px; padding-bottom: 12px; }
.brand { display: flex; align-items: center; gap: 12px; color: var(--ink); text-decoration: none; font-family: var(--display); font-weight: 700; font-size: 20px; padding: 6px 0; }
.brand:hover { color: var(--ink); }
.brand-tile { width: 40px; height: 40px; border-radius: 10px; background: var(--ink); color: var(--yellow); display: flex; align-items: center; justify-content: center; font-family: var(--mono); font-size: 15px; font-weight: 500; }
.nav { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 20px; font-weight: 500; font-size: 16px; }
.nav a, .nav .linklike { color: var(--ink); text-decoration: none; padding: 12px 0; }
.nav a:hover, .nav .linklike:hover { color: var(--accent); }
.nav a[aria-current="page"] { color: var(--accent); box-shadow: inset 0 -2px 0 var(--accent); }
.nav form { margin: 0; }
.linklike { background: none; border: 0; font: inherit; font-weight: 500; cursor: pointer; }

/* Buttons */
.btn { display: inline-block; border: 0; cursor: pointer; text-decoration: none; font: inherit; font-weight: 600; padding: 14px 22px; border-radius: 12px; text-align: center; }
.btn-primary, .nav a.btn-primary { background: var(--accent); color: var(--white); }
.btn-primary:hover, .nav a.btn-primary:hover { background: var(--accent-dark); color: var(--white); }
.btn-dark { background: var(--ink); color: var(--white); }
.btn-dark:hover { background: var(--ink-2); color: var(--white); }
.btn-yellow { background: var(--yellow); color: var(--ink); }
.btn-yellow:hover { background: #F2C22B; color: var(--ink); }
.btn-ghost { background: var(--white); color: var(--ink); border: 1px solid #7B8C97; }
.btn-ghost:hover { color: var(--ink); background: var(--tint); }
.btn-lg { padding: 16px 26px; font-size: 18px; }
.btn-sm { padding: 10px 14px; font-size: 15px; border-radius: 10px; }
.actions { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; }

/* Cards and panels */
.card { background: var(--white); border: 1px solid var(--line); border-radius: 16px; padding: 28px; display: flex; flex-direction: column; gap: 12px; }
.card .num { font-family: var(--mono); font-size: 14px; color: var(--accent); }
.band { background: var(--white); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.dark { background: var(--ink); color: var(--on-dark); }
.dark .muted, .dark p { color: var(--on-dark-muted); }
.dark a { color: var(--yellow); }
.panel-dark { background: var(--ink); color: var(--on-dark); border-radius: 20px; padding: 28px; display: flex; flex-direction: column; gap: 14px; }
.panel-dark .step { background: var(--ink-2); border-radius: 14px; padding: 18px 20px; }
.panel-dark .step b { display: block; font-family: var(--mono); font-weight: 500; font-size: 13px; color: var(--yellow); margin-bottom: 4px; }
.label-yellow { font-family: var(--mono); font-size: 13px; letter-spacing: 0.06em; text-transform: uppercase; color: var(--yellow); }
.tint { background: var(--tint); border-radius: 20px; padding: 40px 32px; }
.accent-band { background: var(--accent); color: var(--white); text-align: center; }
.accent-band p { font-size: 20px; max-width: 600px; margin: 0 auto; }
.facts > div { flex: 1 1 220px; }
.facts strong { display: block; font-family: var(--display); font-size: 20px; }
.facts span { color: var(--muted); font-size: 16px; }

/* Units */
.unit { background: var(--ink-2); border-radius: 14px; padding: 22px; display: flex; flex-direction: column; gap: 8px; color: var(--on-dark); text-decoration: none; }
.unit .tag { font-family: var(--mono); font-size: 13px; color: var(--yellow); }
.unit .name { font-weight: 600; font-size: 19px; }
.unit .note { font-size: 15px; color: var(--on-dark-muted); }
.unit.live { background: var(--yellow); color: var(--ink); }
.unit.live .tag, .unit.live .note { color: var(--ink); }
a.unit:hover { color: var(--on-dark); outline: 2px solid var(--yellow); }
a.unit.live:hover { color: var(--ink); outline: 2px solid var(--white); }
.unit-detail { background: var(--white); border: 1px solid var(--line); border-radius: 16px; padding: 28px; }
.unit-detail ul { margin: 12px 0 0; padding-left: 20px; color: var(--text); }
.unit-detail .tag { font-family: var(--mono); font-size: 13px; color: var(--accent); }

.checks { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 18px; }
.checks li { display: flex; gap: 14px; align-items: flex-start; }
.checks svg { flex: none; margin-top: 2px; }

/* Forms */
.form { display: flex; flex-direction: column; gap: 18px; }
.field { display: flex; flex-direction: column; gap: 6px; }
.field label { font-weight: 600; font-size: 16px; }
.field .help { font-size: 14px; color: var(--muted); }
.field ul.errorlist, .form > ul.errorlist { list-style: none; margin: 0; padding: 0; color: var(--error); font-size: 15px; font-weight: 500; }
input[type=text], input[type=email], input[type=password], input[type=number], select, textarea {
  width: 100%; min-height: 50px; padding: 12px 14px; border: 1px solid #7B8C97; border-radius: 10px; font: inherit; background: var(--white); color: var(--ink);
}
textarea { min-height: 110px; resize: vertical; }
input:focus-visible, select:focus-visible, textarea:focus-visible, .btn:focus-visible, a:focus-visible, button:focus-visible { outline: 3px solid #1D6FD8; outline-offset: 2px; }
.hp { position: absolute; left: -9999px; width: 1px; height: 1px; overflow: hidden; }
.inline-form { display: flex; flex-wrap: wrap; gap: 10px; }
.inline-form input { flex: 1 1 220px; width: auto; }

.flash { padding: 14px 18px; border-radius: 12px; font-weight: 500; margin: 16px 0 0; }
.flash.success { background: var(--tint); color: var(--accent-dark); border: 1px solid #9CC9BC; }
.flash.error { background: #FBE9E7; color: var(--error); border: 1px solid #E5AFA9; }

/* Footer */
.site-footer { background: var(--ink); color: var(--on-dark-muted); font-size: 15px; padding: 40px 0; }
.site-footer .wrap { display: flex; flex-wrap: wrap; gap: 28px; justify-content: space-between; }
.site-footer .wrap > div { flex: 1 1 240px; min-width: 0; display: flex; flex-direction: column; gap: 8px; }
.site-footer a { color: var(--yellow); }
.site-footer .foot-brand { font-family: var(--display); font-weight: 700; font-size: 18px; color: var(--white); }

/* Dashboard */
.stat { font-family: var(--display); font-weight: 700; font-size: 40px; line-height: 1; }
table.plain { width: 100%; border-collapse: collapse; font-size: 16px; }
table.plain th, table.plain td { text-align: left; padding: 10px 8px; border-bottom: 1px solid var(--line); }
.table-scroll { overflow-x: auto; }
.pill { display: inline-block; padding: 2px 10px; border-radius: 999px; font-size: 14px; font-weight: 600; }
.pill.ok { background: var(--tint); color: var(--accent-dark); }
.pill.no { background: #FBE9E7; color: var(--error); }

/* Simulation */
.sim { display: flex; flex-wrap: wrap; gap: 24px; align-items: flex-start; }
.sim-stage { flex: 1 1 300px; min-width: 0; background: var(--white); border: 1px solid var(--line); border-radius: 16px; padding: 20px; }
.sim-side { flex: 1 1 380px; min-width: 0; display: flex; flex-direction: column; gap: 20px; }
.sim-stage svg { display: block; width: 100%; height: auto; }
.control { display: flex; flex-direction: column; gap: 4px; }
.control label { display: flex; justify-content: space-between; gap: 12px; font-weight: 600; font-size: 16px; }
.control output { font-family: var(--mono); font-weight: 500; }
input[type=range] { width: 100%; height: 44px; accent-color: var(--accent); }
.readouts { display: flex; flex-wrap: wrap; gap: 12px; }
.readout { flex: 1 1 150px; background: var(--ground); border: 1px solid var(--line); border-radius: 12px; padding: 12px 14px; }
.readout span { display: block; font-size: 14px; color: var(--muted); }
.readout b { font-family: var(--mono); font-weight: 500; font-size: 18px; }
.tabs { display: flex; flex-wrap: wrap; gap: 10px; }
.tabs button[aria-pressed="true"] { background: var(--ink); color: var(--white); border-color: var(--ink); }
.feedback { padding: 14px 16px; border-radius: 12px; font-size: 16px; }
.feedback.ok { background: var(--tint); color: var(--accent-dark); border: 1px solid #9CC9BC; }
.feedback.no { background: #FBE9E7; color: var(--error); border: 1px solid #E5AFA9; }
.feedback.info { background: #FFF6D6; color: #5A4500; border: 1px solid #E6CF7A; }
[hidden] { display: none !important; }

@media (max-width: 640px) {
  .section { padding: 52px 0; }
  .tint { padding: 28px 20px; }
  .nav { gap: 0 16px; font-size: 15px; }
  .card, .unit-detail { padding: 22px; }
}

/* Study guides */
.formulas { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 10px; }
.formulas li { font-family: var(--mono); font-size: 16px; background: var(--ground); border: 1px solid var(--line); border-radius: 10px; padding: 10px 14px; white-space: pre-wrap; overflow-wrap: anywhere; }
.plain-list { margin: 0; padding-left: 20px; color: var(--text); display: flex; flex-direction: column; gap: 10px; }
.plain-list.cols { display: block; columns: 2 260px; }
.plain-list.cols li { margin-bottom: 8px; break-inside: avoid; }

/* Practice questions */
.quiz-top { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; justify-content: space-between; }
.choices { display: flex; flex-direction: column; gap: 10px; }
.choice { text-align: left; font: inherit; color: var(--ink); background: var(--white); border: 1px solid #7B8C97; border-radius: 12px; padding: 14px 16px; min-height: 52px; cursor: pointer; }
.choice:hover:not(:disabled) { background: var(--tint); border-color: var(--accent); }
.choice:disabled { cursor: default; color: var(--muted); }
.choice.right { background: var(--tint); border: 2px solid var(--accent); color: var(--accent-dark); font-weight: 600; }
.choice.wrong { background: #FBE9E7; border: 2px solid var(--error); color: var(--error); }

/* FAQ */
details.faq { background: var(--white); border: 1px solid var(--line); border-radius: 14px; padding: 4px 22px; }
details.faq summary { cursor: pointer; font-family: var(--display); font-weight: 700; font-size: 20px; padding: 16px 0; }
details.faq p { color: var(--text); padding-bottom: 18px; }

.nav a.btn { padding: 10px 14px; white-space: nowrap; }

/* Locked (students only) */
.lock-icon { display: inline-block; vertical-align: -2px; flex: none; }
.lock-note { display: inline-flex; align-items: center; gap: 6px; font-size: 15px; font-weight: 600; color: var(--muted); }
.free-tag { background: var(--yellow); color: var(--ink); padding: 1px 7px; border-radius: 6px; font-weight: 500; }
.is-locked { background: #EEF2F1; }
.is-locked h3, .is-locked h3 a { color: var(--ink-2) !important; }
.unit.locked { background: rgba(255, 255, 255, 0.04); border: 1px dashed #3C5163; }
.unit.locked .tag { color: var(--on-dark-muted); display: inline-flex; align-items: center; gap: 5px; }
.unit.locked .name { color: var(--on-dark-muted); }
.locked-card { background: var(--ink); color: var(--on-dark); border-radius: 20px; padding: 32px; display: flex; flex-direction: column; gap: 16px; }
.locked-card p { color: var(--on-dark-muted); }
.locked-card strong { color: var(--white); }
.lock-badge { display: inline-flex; align-items: center; gap: 8px; align-self: flex-start; background: var(--yellow); color: var(--ink); font-family: var(--mono); font-size: 13px; letter-spacing: 0.06em; text-transform: uppercase; padding: 6px 12px; border-radius: 999px; }
.locked-included { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 4px; }
.locked-included span { display: inline-flex; align-items: center; gap: 6px; background: var(--ground); border: 1px solid var(--line); border-radius: 999px; padding: 6px 12px; font-size: 14px; font-weight: 600; color: var(--muted); }
.btn-ghost-dark { background: transparent; color: var(--white); border: 1px solid #7B8C97; }
.btn-ghost-dark:hover { background: var(--ink-2); color: var(--white); }

/* Sign in with Google */
.google-form { margin: 0; }
.btn-google { width: 100%; display: flex; align-items: center; justify-content: center; gap: 12px; background: #fff; color: #1F1F1F; border: 1px solid #747775; font-weight: 600; }
.btn-google:hover { background: #F8FAFF; color: #1F1F1F; border-color: #1F1F1F; }
.btn-google svg { flex: none; }
.or-line { display: flex; align-items: center; gap: 12px; color: var(--muted); font-size: 14px; margin: 6px 0; }
.or-line::before, .or-line::after { content: ""; flex: 1; height: 1px; background: var(--line); }
.locked-google { max-width: 420px; margin: 16px 0 4px; }
.locked-google .or-line { color: var(--on-dark-muted); }
.locked-google .or-line::before, .locked-google .or-line::after { background: rgba(255, 255, 255, 0.2); }
main.allauth-main { max-width: 560px; margin: 0 auto; padding: 56px 24px 80px; display: flex; flex-direction: column; gap: 16px; }