:root {
  --bg: #fbfaf6; --card: #ffffff; --ink: #121417; --muted: #5b6270; --line: #e7e4dc;
  --accent: #0f9d6e; --accent-ink: #ffffff; --accent-soft: #e3f6ee; --pop: #ffd23f; --pop-soft: #fff6d1;
  --danger: #d6453d; --shadow: 0 1px 2px rgba(18,20,23,.05), 0 8px 24px rgba(18,20,23,.06); --r: 16px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1113; --card: #171a1d; --ink: #f2f1ec; --muted: #9aa1ad; --line: #2a2e33;
    --accent: #2fd39a; --accent-ink: #062b1d; --accent-soft: #11291f; --pop: #ffd23f; --pop-soft: #2d2711;
    --shadow: 0 1px 2px rgba(0,0,0,.3);
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 16px/1.55 "Inter", system-ui, sans-serif; }
h1, h2, h3, .logo { font-family: "Space Grotesk", "Inter", sans-serif; letter-spacing: -.02em; line-height: 1.12; }
a { color: inherit; }
.wrap { max-width: 1120px; margin: 0 auto; padding: 0 20px; }
.btn { display: inline-flex; align-items: center; gap: 8px; border: 0; cursor: pointer; text-decoration: none; font: 600 15px "Inter", sans-serif;
  background: var(--ink); color: var(--bg); padding: 12px 20px; border-radius: 999px; transition: transform .15s; }
.btn:hover { transform: translateY(-1px); }
.btn.accent { background: var(--accent); color: var(--accent-ink); }
.btn.ghost { background: transparent; color: var(--ink); border: 1.5px solid var(--line); }
.btn.small { padding: 8px 14px; font-size: 14px; }
.btn[disabled] { opacity: .5; cursor: not-allowed; transform: none; }
.pill { display: inline-block; font-size: 12px; font-weight: 600; padding: 3px 10px; border-radius: 999px; background: var(--accent-soft); color: var(--accent); }
.pill.pop { background: var(--pop-soft); color: #8a6a00; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .pill.pop { color: var(--pop); } }
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--r); box-shadow: var(--shadow); }
.muted { color: var(--muted); }
.hl { background: linear-gradient(transparent 60%, var(--pop) 60%); padding: 0 2px; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .hl { background: none; color: var(--pop); } }

/* nav */
.nav { position: sticky; top: 0; z-index: 10; background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(10px); border-bottom: 1px solid var(--line); }
.nav .wrap { display: flex; align-items: center; justify-content: space-between; height: 64px; gap: 12px; }
.logo { font-size: 22px; font-weight: 700; text-decoration: none; }
.logo b { color: var(--accent); }
.nav-links { display: flex; gap: 18px; align-items: center; font-size: 15px; }
.nav-links a { text-decoration: none; color: var(--muted); }
.nav-links a:hover, .nav-links a.on { color: var(--ink); }
@media (max-width: 720px) { .nav-links .hide-m { display: none; } }

/* landing */
.hero { padding: 72px 0 48px; }
.hero h1 { font-size: clamp(38px, 6.5vw, 68px); margin: 14px 0 18px; max-width: 900px; }
.hero p.lead { font-size: clamp(17px, 2vw, 20px); color: var(--muted); max-width: 640px; margin: 0 0 28px; }
.hero .ctas { display: flex; gap: 12px; flex-wrap: wrap; }
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin-top: 48px; }
.stat { padding: 18px; }
.stat b { display: block; font: 700 30px "Space Grotesk", sans-serif; }
.stat span { color: var(--muted); font-size: 14px; }
@media (max-width: 720px) { .stats { grid-template-columns: repeat(2, 1fr); } }
section.block { padding: 64px 0; }
section.block h2 { font-size: clamp(28px, 4vw, 42px); margin: 8px 0 12px; }
section.block > .wrap > p.sub { color: var(--muted); max-width: 640px; margin: 0 0 32px; font-size: 18px; }
.kicker { font-size: 13px; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--accent); }
.ba { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.ba .card { padding: 24px; }
.ba h3 { margin: 0 0 12px; font-size: 18px; }
.ba .before { border-style: dashed; }
.ba .before li { color: var(--muted); text-decoration: line-through; text-decoration-color: var(--danger); }
.ba ul { margin: 0; padding-left: 18px; display: grid; gap: 10px; }
.ba .after { border: 2px solid var(--accent); }
@media (max-width: 760px) { .ba { grid-template-columns: 1fr; } }
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.step { padding: 22px; }
.step .num { font: 700 14px "Space Grotesk"; color: var(--accent); }
.step h3 { margin: 6px 0; font-size: 19px; }
.step p { margin: 0; color: var(--muted); font-size: 15px; }
@media (max-width: 760px) { .steps { grid-template-columns: 1fr; } }
.ladder { display: grid; gap: 10px; }
.rung { display: grid; grid-template-columns: 56px 1fr auto; gap: 16px; align-items: center; padding: 16px 20px; }
.rung .n { font: 700 26px "Space Grotesk"; color: var(--muted); }
.rung h3 { margin: 0 0 4px; font-size: 18px; }
.rung .meta { font-size: 14px; color: var(--muted); }
.rung.cap { border: 2px solid var(--pop); background: var(--pop-soft); }
.rung.cap .n { color: var(--ink); }
@media (max-width: 640px) { .rung { grid-template-columns: 40px 1fr; } .rung .right { grid-column: 2; } }
.certs { display: grid; grid-template-columns: 1.2fr 1fr; gap: 16px; }
.certs .card { padding: 24px; }
.certs ul { padding-left: 18px; margin: 10px 0 0; display: grid; gap: 10px; }
@media (max-width: 760px) { .certs { grid-template-columns: 1fr; } }
.plans { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; align-items: stretch; }
.plan { padding: 22px; display: flex; flex-direction: column; position: relative; }
.plan.featured { border: 2px solid var(--accent); }
.plan h3 { margin: 0; font-size: 20px; }
.plan .price { font: 700 36px "Space Grotesk"; margin: 10px 0 2px; }
.plan .per { font-size: 13px; color: var(--muted); }
.plan ul { padding-left: 18px; margin: 16px 0 20px; display: grid; align-content: start; gap: 8px; font-size: 14.5px; flex: 1; }
.plan .badge { position: absolute; top: -11px; left: 20px; }
@media (max-width: 960px) { .plans { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .plans { grid-template-columns: 1fr; } }
.faq details { padding: 16px 20px; margin-bottom: 10px; }
.faq summary { cursor: pointer; font-weight: 600; }
.faq p { color: var(--muted); margin: 10px 0 0; }
footer { padding: 40px 0; border-top: 1px solid var(--line); color: var(--muted); font-size: 14px; }

/* app */
.app-main { padding: 32px 0 80px; }
.grid2 { display: grid; grid-template-columns: 1fr 340px; gap: 20px; align-items: start; }
@media (max-width: 900px) { .grid2 { grid-template-columns: 1fr; } }
.progressbar { height: 10px; border-radius: 99px; background: var(--line); overflow: hidden; }
.progressbar i { display: block; height: 100%; background: var(--accent); border-radius: 99px; }
.pcard { display: grid; grid-template-columns: 52px 1fr auto; gap: 14px; align-items: center; padding: 16px 18px; text-decoration: none; margin-bottom: 10px; }
.pcard .n { width: 44px; height: 44px; border-radius: 12px; display: grid; place-items: center; font: 700 18px "Space Grotesk"; background: var(--accent-soft); color: var(--accent); }
.pcard.locked { opacity: .6; }
.pcard.locked .n { background: var(--line); color: var(--muted); }
.pcard.done .n { background: var(--accent); color: var(--accent-ink); }
.pcard h3 { margin: 0 0 2px; font-size: 16.5px; }
.pcard .meta { font-size: 13.5px; color: var(--muted); }
@media (max-width: 560px) { .pcard { grid-template-columns: 44px 1fr; } .pcard .right { grid-column: 2; } }
.panel { padding: 22px; margin-bottom: 16px; }
.panel h2, .panel h3 { margin-top: 0; }
.brief { border-left: 4px solid var(--pop); background: var(--pop-soft); padding: 16px 18px; border-radius: 0 12px 12px 0; margin: 14px 0; }
.brief .from { font-size: 13px; color: var(--muted); margin-bottom: 6px; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip { font-size: 13px; padding: 3px 10px; border-radius: 99px; border: 1px solid var(--line); color: var(--muted); }
.files a { display: flex; justify-content: space-between; align-items: center; padding: 10px 14px; border: 1px solid var(--line); border-radius: 12px; margin-bottom: 8px; text-decoration: none; font-weight: 500; }
.files a:hover { border-color: var(--accent); }
.check { display: grid; gap: 6px; padding: 14px 0; border-bottom: 1px solid var(--line); }
.check:last-of-type { border-bottom: 0; }
.check label { font-weight: 600; font-size: 15px; }
.check .row { display: flex; gap: 8px; align-items: center; }
input, select, textarea { font: inherit; color: var(--ink); background: var(--bg); border: 1.5px solid var(--line); border-radius: 10px; padding: 10px 12px; width: 100%; }
input:focus, select:focus, textarea:focus { outline: none; border-color: var(--accent); }
.check .unit { color: var(--muted); font-size: 14px; min-width: 40px; }
.check .res { font-size: 14px; font-weight: 600; min-width: 24px; }
.ok { color: var(--accent); } .bad { color: var(--danger); }
.bullet { padding: 14px 16px; border-radius: 12px; background: var(--accent-soft); font-size: 15px; }
.lock { text-align: center; padding: 40px 24px; }
.auth { max-width: 440px; margin: 40px auto; padding: 28px; }
.auth h2 { margin: 0 0 6px; }
.auth form { display: grid; gap: 12px; margin-top: 18px; }
.tabs { display: flex; gap: 6px; background: var(--bg); border: 1px solid var(--line); border-radius: 99px; padding: 4px; }
.tabs button { flex: 1; border: 0; background: transparent; padding: 8px; border-radius: 99px; font: 600 14px Inter; color: var(--muted); cursor: pointer; }
.tabs button.on { background: var(--card); color: var(--ink); box-shadow: var(--shadow); }
.err { color: var(--danger); font-size: 14px; min-height: 20px; }
.toast { position: fixed; bottom: 20px; left: 50%; transform: translateX(-50%); background: var(--ink); color: var(--bg); padding: 12px 18px; border-radius: 12px; font-weight: 600; z-index: 50; }
.qa { border-top: 1px solid var(--line); padding: 12px 0; }
.qa summary { cursor: pointer; font-weight: 600; }
.qa p { margin: 8px 0 0; color: var(--muted); }
.resume-out { white-space: pre-wrap; font: 14px/1.6 ui-monospace, Menlo, monospace; background: var(--bg); border: 1px solid var(--line); border-radius: 12px; padding: 16px; }
.hide { display: none !important; }
h1.page { font-size: clamp(28px, 4vw, 38px); margin: 0 0 6px; }

/* certificate */
.cert-page { background: #e9e6dd; min-height: 100vh; padding: 32px 16px; color: #121417; }
.cert { max-width: 860px; margin: 0 auto; background: #fffdf7; border: 10px solid #121417; outline: 2px solid #0f9d6e; outline-offset: -18px; padding: 48px 56px; }
.cert-top { display: flex; justify-content: space-between; align-items: center; }
.cert-top .logo b { color: #0f9d6e; }
.cert-id { font: 600 13px ui-monospace, monospace; color: #5b6270; }
.cert-kicker { margin: 36px 0 4px; letter-spacing: .14em; text-transform: uppercase; font-weight: 700; color: #0f9d6e; font-size: 13px; }
.cert h1 { font-size: 48px; margin: 0 0 12px; }
.cert-lead { font-size: 17px; max-width: 640px; }
.cert-list { columns: 2; font-size: 13.5px; padding-left: 0; list-style: none; margin: 22px 0; }
.cert-list li { break-inside: avoid; margin-bottom: 8px; }
.cert-list b { color: #0f9d6e; margin-right: 6px; }
.cert-list span { display: block; color: #5b6270; font-size: 12px; padding-left: 26px; }
.cert-foot { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; border-top: 1px solid #ddd8cc; padding-top: 18px; font-size: 13px; }
.cert-foot span { display: block; color: #5b6270; } .cert-foot b { word-break: break-all; }
.cert-note { font-size: 11.5px; color: #5b6270; margin: 18px 0 0; }
.cert-actions { max-width: 860px; margin: 18px auto 0; display: flex; gap: 10px; }
.cert-actions button, .cert-actions a { font: 600 14px Inter; padding: 10px 16px; border-radius: 99px; border: 0; background: #121417; color: #fff; cursor: pointer; text-decoration: none; }
.cert-actions a { background: #0a66c2; }
.cert-missing { max-width: 600px; margin: 80px auto; text-align: center; }
@media (max-width: 640px) { .cert { padding: 28px 22px; } .cert h1 { font-size: 34px; } .cert-list { columns: 1; } .cert-foot { grid-template-columns: 1fr; } }
@media print { .no-print { display: none; } .cert-page { background: #fff; padding: 0; } @page { size: A4 landscape; margin: 10mm; } .cert { border-width: 6px; padding: 28px 40px; } .cert h1 { font-size: 38px; } }

/* ---------- gen z bits */
.sticker { display: inline-flex; align-items: center; gap: 6px; font: 700 13px "Space Grotesk", sans-serif; padding: 6px 12px; border-radius: 10px;
  background: var(--pop); color: #121417; border: 2px solid #121417; box-shadow: 3px 3px 0 #121417; transform: rotate(-2deg); }
.sticker.alt { background: var(--accent); color: #fff; transform: rotate(1.5deg); }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .sticker { border-color: #000; box-shadow: 3px 3px 0 #000; } :root:not([data-theme="light"]) .sticker.alt { color: #062b1d; } }
.lvl { display: flex; gap: 10px; flex-wrap: wrap; margin: 4px 0 6px; }
.hero { position: relative; overflow: hidden; }
.blob { position: absolute; border-radius: 50%; filter: blur(70px); opacity: .35; z-index: -1; pointer-events: none; }
.blob.a { width: 380px; height: 380px; background: var(--accent); top: -80px; right: -60px; }
.blob.b { width: 300px; height: 300px; background: var(--pop); top: 200px; right: 220px; opacity: .25; }
.hero-stickers { position: absolute; right: 20px; top: 90px; display: grid; gap: 14px; justify-items: end; }
@media (max-width: 1180px) { .hero-stickers { position: static; display: flex; flex-wrap: wrap; justify-items: start; margin-top: 22px; } }
.marquee { overflow: hidden; border-block: 2px solid var(--ink); background: var(--pop); color: #121417; padding: 10px 0; }
.marquee div { display: flex; gap: 36px; width: max-content; animation: slide 38s linear infinite; font: 700 15px "Space Grotesk", sans-serif; white-space: nowrap; }
@keyframes slide { to { transform: translateX(-50%); } }
@media (prefers-reduced-motion: reduce) { .marquee div { animation: none; } }
.era { font: 700 13px "Space Grotesk"; letter-spacing: .06em; text-transform: uppercase; color: var(--muted); margin: 18px 0 2px; }
.rung .emo { font-size: 26px; }
.confetti { position: fixed; inset: 0; pointer-events: none; z-index: 60; overflow: hidden; }
.confetti i { position: absolute; top: -40px; font-style: normal; animation: fall 2.6s cubic-bezier(.2,.6,.4,1) forwards; }
@keyframes fall { to { transform: translateY(110vh) rotate(540deg); } }

/* ---------- python lab */
.lab { margin-top: 4px; }
.lab-head { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.lab-head h3 { margin: 0; }
.lab-actions { margin-left: auto; display: flex; gap: 6px; flex-wrap: wrap; }
textarea.code { font: 14px/1.6 ui-monospace, "SF Mono", Menlo, monospace; min-height: 220px; resize: vertical; tab-size: 4; white-space: pre; overflow-x: auto;
  background: #0f1113; color: #e8f5ee; border-color: #2a2e33; }
.pyout { margin-top: 12px; border: 1px dashed var(--line); border-radius: 12px; padding: 12px; min-height: 60px; overflow-x: auto; }
.pyout pre { margin: 0 0 8px; font: 13.5px/1.5 ui-monospace, Menlo, monospace; white-space: pre-wrap; }
.pyout .pyerr { color: var(--danger); }
.pyout img { max-width: 100%; background: #fff; border-radius: 8px; margin: 6px 0; }
.pytable { overflow-x: auto; margin-bottom: 8px; }
.pytable table { border-collapse: collapse; font-size: 13px; }
.pytable th, .pytable td { padding: 5px 10px; border-bottom: 1px solid var(--line); text-align: right; white-space: nowrap; }
.pytable thead th { background: var(--accent-soft); }
code { font: 13px ui-monospace, Menlo, monospace; background: var(--accent-soft); padding: 1px 6px; border-radius: 6px; }