/* Corsi di programmazione. Idea guida: la lavagna.
   Il codice sta su un'ardesia verde scuro e la sintassi usa i colori del gesso;
   tutto il resto è carta e inchiostro, sobrio, per lasciare spazio al codice.
   Ogni corso ha il suo gesso (--mark): giallo per AI Engineer, corallo per Full Stack.
   Il verde (--accent) segna solo le azioni, --mark solo l'avanzamento e l'identità del corso. */
:root {
  --bg: #f4f6f3;
  --surface: #ffffff;
  --ink: #17211e;
  --muted: #56645f;
  --line: #d5ddd8;
  --accent: #17694f;
  --accent-hover: #0f5440;
  --on-accent: #ffffff;
  --mark: #f2d15a;
  --on-mark: #2a2300;
  --ok: #1f7a4b;
  --ok-soft: #e3f2e9;
  --bad: #b83a2a;
  --slate: #183029;
  --slate-edge: #10241e;
  --chalk: #e7efe9;
  --hl-k: #f2d15a;
  --hl-s: #f4a58c;
  --hl-n: #9ccbf2;
  --hl-c: #8ea89e;
  --hl-f: #cbbcf5;
  --hl-t: #9ccbf2;
  --font: "Atkinson Hyperlegible Next", "Segoe UI", system-ui, sans-serif;
  --mono: "Atkinson Hyperlegible Mono", "Cascadia Code", Consolas, monospace;
  --r-lg: 18px;
  --r-md: 12px;
  --r-sm: 8px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1916; --surface: #15221e; --ink: #e7efe9; --muted: #9db0a8; --line: #27382f;
    --accent: #7fd3b2; --accent-hover: #a2e3c9; --on-accent: #0c1a15;
    --ok: #86dc9f; --ok-soft: #173326; --bad: #ff8f7a; --slate: #1a352e; --slate-edge: #23463d;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0f1916; --surface: #15221e; --ink: #e7efe9; --muted: #9db0a8; --line: #27382f;
  --accent: #7fd3b2; --accent-hover: #a2e3c9; --on-accent: #0c1a15;
  --ok: #86dc9f; --ok-soft: #173326; --bad: #ff8f7a; --slate: #1a352e; --slate-edge: #23463d;
  color-scheme: dark;
}
[data-course="fullstack"] { --mark: #f29c82; --on-mark: #3a1206; }

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 400 17px/1.6 var(--font); }
a { color: var(--accent); text-underline-offset: 3px; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; border-radius: 4px; }
[hidden] { display: none !important; }
::selection { background: var(--mark); color: var(--on-mark); }

/* ---------- intestazione ---------- */
.top { position: sticky; top: 0; z-index: 5; background: color-mix(in srgb, var(--bg) 92%, transparent); backdrop-filter: blur(8px); border-bottom: 1px solid var(--line); }
.top-in { max-width: 780px; margin: 0 auto; padding: 12px 20px 10px; display: grid; gap: 10px; }
body[data-course=""] .top-in { max-width: 1080px; }
.top-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.brandbar { display: flex; align-items: baseline; gap: 8px; min-width: 0; flex-wrap: wrap; }
.brand { font: 800 18px/1.2 var(--font); color: var(--ink); text-decoration: none; letter-spacing: -0.01em; }
.brand span { background: linear-gradient(transparent 60%, var(--mark) 60%); padding: 0 1px; }
.back { font-size: 15px; color: var(--muted); text-decoration: none; }
.back:hover { color: var(--accent); text-decoration: underline; }
.sep { color: var(--line); }
.pill { font: 600 13px/1 var(--font); color: var(--muted); border: 1px solid var(--line); border-radius: 99px; padding: 6px 10px; white-space: nowrap; }
.pill.ok { color: var(--ok); border-color: var(--ok); }
.pill.err { color: var(--bad); border-color: var(--bad); }
.track { display: flex; gap: 4px; }
.track i { flex: 1; height: 6px; border-radius: 3px; background: var(--line); }
.track i.on { background: var(--mark); }
.track i.part { background: linear-gradient(90deg, var(--mark) 50%, var(--line) 50%); }

/* ---------- impaginazione e tipografia ---------- */
main { max-width: 780px; margin: 0 auto; padding: 36px 20px 96px; display: grid; gap: 36px; }
h1 { font: 800 clamp(34px, 6.4vw, 54px)/1.04 var(--font); margin: 0; letter-spacing: -0.025em; text-wrap: balance; }
h2 { font: 800 clamp(24px, 3.4vw, 30px)/1.15 var(--font); margin: 0; letter-spacing: -0.015em; text-wrap: balance; }
h3 { font: 700 19px/1.3 var(--font); margin: 0; }
p { margin: 0; }
.lead { color: var(--muted); font-size: 18.5px; line-height: 1.55; max-width: 62ch; }
.eyebrow { font-size: 15px; font-weight: 500; color: var(--muted); }
.muted { color: var(--muted); font-size: 15.5px; }
code { font: 400 .9em var(--mono); background: color-mix(in srgb, var(--accent) 11%, transparent); padding: 1px 5px; border-radius: 5px; }
.row { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
.row.tight { gap: 8px; flex-wrap: nowrap; }
.stack { display: grid; gap: 14px; }
.hero { display: grid; gap: 16px; }
.crumb { font-size: 15px; }
.crumb a { text-decoration: none; }
.crumb a:hover { text-decoration: underline; }
.foot { color: var(--muted); font-size: 14.5px; border-top: 1px solid var(--line); padding-top: 18px; }

/* ---------- la lavagna: blocchi di codice ---------- */
pre { margin: 0; background: var(--slate); color: var(--chalk); font: 400 14.5px/1.65 var(--mono); padding: 16px 18px; border-radius: var(--r-md); overflow-x: auto; box-shadow: inset 0 0 0 1px var(--slate-edge); tab-size: 4; }
pre code { background: none; padding: 0; font: inherit; color: inherit; }
.hl-k { color: var(--hl-k); }
.hl-s { color: var(--hl-s); }
.hl-n { color: var(--hl-n); }
.hl-c { color: var(--hl-c); font-style: italic; }
.hl-f { color: var(--hl-f); }
.hl-t { color: var(--hl-t); }
.lang { font: 600 13.5px/1 var(--font); color: var(--muted); justify-self: start; }

.sample { display: grid; gap: 6px; min-width: 0; }
.sample > pre:has(+ .result) { border-bottom-left-radius: 0; border-bottom-right-radius: 0; }
.result { margin-top: -6px; border: 1px solid var(--line); border-top: 0; border-radius: 0 0 var(--r-md) var(--r-md); background: var(--surface); padding: 10px 18px 14px; display: grid; gap: 6px; min-width: 0; position: relative; }
.result::before { content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 4px; background: var(--ok); border-bottom-left-radius: var(--r-md); }
.result > .eyebrow, .console > .eyebrow { font: 700 13px/1.2 var(--font); color: var(--ok); }
.result pre { background: none; box-shadow: none; color: var(--ink); padding: 0; border-radius: 0; font-size: 14px; }
.console { display: grid; gap: 4px; }
.console pre { font-size: 13.5px; }
.pv { display: grid; min-width: 0; }
iframe.preview { display: block; width: 100%; height: 200px; border: 1px solid var(--line); border-radius: var(--r-sm); background: #fff; resize: vertical; }
.ghosts { position: fixed; left: 0; top: 0; width: 0; height: 0; opacity: 0; pointer-events: none; z-index: -1; }
iframe.ghost, .ghosts iframe { position: absolute; left: 0; top: 0; width: 800px; height: 600px; border: 0; }
.given summary { cursor: pointer; font-size: 15px; font-weight: 600; color: var(--accent); }
.given pre { margin-top: 8px; font-size: 13.5px; max-height: 300px; }

/* ---------- pulsanti ed etichette di stato ---------- */
.btn { font: 700 15.5px/1 var(--font); border: 1.5px solid var(--line); background: var(--surface); color: var(--ink); padding: 12px 16px; border-radius: var(--r-sm); cursor: pointer; text-decoration: none; display: inline-block; transition: border-color .15s, background-color .15s; }
.btn:hover { border-color: var(--accent); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--on-accent); }
.btn.primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); }
.btn.quiet { border-color: transparent; background: none; color: var(--accent); padding-left: 6px; padding-right: 6px; }
.btn.quiet:hover { text-decoration: underline; }
.btn:disabled { opacity: .55; cursor: default; }
.chip { font: 700 13px/1 var(--font); padding: 6px 10px; border-radius: 99px; border: 1px solid var(--line); color: var(--muted); white-space: nowrap; }
.chip.part { background: var(--mark); border-color: var(--mark); color: var(--on-mark); }
.chip.done { background: var(--ok-soft); border-color: transparent; color: var(--ok); }

/* ---------- elenchi di moduli e lezioni ---------- */
.stage { display: grid; gap: 10px; }
.lessons { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--line); }
.lessons a, .lessons .soon { display: grid; grid-template-columns: 48px 1fr auto; gap: 12px; align-items: center; padding: 15px 6px; border-bottom: 1px solid var(--line); color: var(--ink); text-decoration: none; }
.lessons a:hover { background: color-mix(in srgb, var(--mark) 14%, transparent); }
.lessons a:hover .lt { color: var(--accent); }
.lessons .soon { align-items: start; color: var(--muted); }
.lessons .soon .lt { color: var(--ink); }
.num { font: 800 22px/1 var(--font); color: var(--muted); font-variant-numeric: tabular-nums; letter-spacing: -0.02em; }
.lt { font-weight: 700; }
.lm { display: block; font-size: 14.5px; color: var(--muted); }

/* ---------- lezione ---------- */
.body { display: grid; gap: 16px; }
.body p { max-width: 66ch; }
.body h3 { margin-top: 12px; font-size: 21px; }
.note { border-left: 4px solid var(--mark); padding: 12px 16px; background: var(--surface); border-radius: 0 var(--r-sm) var(--r-sm) 0; font-size: 16px; }
.q, .ex { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-md); padding: 18px; display: grid; gap: 12px; min-width: 0; }
.q.solved, .ex.passed { border-color: var(--ok); box-shadow: inset 4px 0 0 var(--ok); }
.qt { font-weight: 700; }
.opts { display: grid; gap: 8px; }
.opt { text-align: left; font: 400 16px/1.45 var(--font); background: var(--bg); color: var(--ink); border: 1.5px solid var(--line); border-radius: var(--r-sm); padding: 11px 14px; cursor: pointer; }
.opt:hover:not(:disabled) { border-color: var(--accent); }
.opt.right { border-color: var(--ok); background: var(--ok-soft); color: var(--ok); font-weight: 700; }
.opt.right::before { content: "✓ "; }
.opt.wrong { border-color: var(--bad); color: var(--bad); text-decoration: line-through; }
.opt.wrong::before { content: "✗ "; }
.why { font-size: 15.5px; color: var(--muted); }
.ex-head { display: flex; justify-content: space-between; gap: 10px; align-items: baseline; }
textarea.code { width: 100%; background: var(--slate); color: var(--chalk); caret-color: var(--mark); border: 0; box-shadow: inset 0 0 0 1px var(--slate-edge); border-radius: var(--r-md); padding: 16px 18px; font: 400 14.5px/1.65 var(--mono); resize: vertical; tab-size: 4; white-space: pre; overflow: auto; }
textarea.code:focus-visible { outline: 3px solid var(--mark); outline-offset: 2px; }
textarea.plain { width: 100%; background: var(--bg); color: var(--ink); border: 1.5px solid var(--line); border-radius: var(--r-sm); padding: 12px; font: 400 16px/1.5 var(--font); resize: vertical; }
@media (max-width: 600px) { textarea.code { font-size: 16px; line-height: 1.5; } }
.out { display: grid; gap: 8px; }
.out pre { font-size: 13.5px; max-height: 260px; }
.errbox { color: var(--bad); font: 400 14px/1.5 var(--mono); border: 1.5px solid var(--bad); border-radius: var(--r-sm); padding: 10px 12px; overflow-x: auto; white-space: pre-wrap; }
.tests { list-style: none; margin: 0; padding: 0; display: grid; gap: 6px; font-size: 15.5px; }
.tests li { display: grid; grid-template-columns: 22px 1fr; gap: 4px; }
.tests .t-ok { color: var(--ok); }
.tests .t-no { color: var(--bad); }
.tests small { display: block; font: 400 13px/1.45 var(--mono); color: var(--muted); }
.passmsg { color: var(--ok); font-weight: 700; }
.banner { padding: 16px 18px; border-radius: var(--r-md); border: 1px solid var(--line); background: var(--surface); display: grid; gap: 12px; }
.banner.good { border-color: var(--ok); }
.nav { display: flex; justify-content: space-between; gap: 10px; flex-wrap: wrap; }

/* ---------- verifica finale ---------- */
.model { border-left: 4px solid var(--accent); padding: 10px 14px; background: var(--bg); border-radius: 0 var(--r-sm) var(--r-sm) 0; display: grid; gap: 8px; font-size: 16px; }
.ticks { display: grid; gap: 8px; }
.ticks label { display: grid; grid-template-columns: 24px 1fr; gap: 6px; align-items: start; font-size: 15.5px; cursor: pointer; }
.ticks input { width: 18px; height: 18px; margin-top: 3px; accent-color: var(--accent); }
.score { font: 800 clamp(64px, 18vw, 112px)/1 var(--font); font-variant-numeric: tabular-nums; letter-spacing: -0.04em; }
.score small { font-size: .3em; color: var(--muted); letter-spacing: 0; }
.timer { font: 600 14px/1 var(--mono); color: var(--muted); }

/* ---------- pagina iniziale ---------- */
main.wide { max-width: 1080px; gap: 56px; }
main.wide > :not(.courses) { width: 100%; max-width: 780px; justify-self: start; }
main.wide .hero { padding-top: 12px; }
main.wide .hero h1 { max-width: 19ch; font-size: clamp(36px, 6.6vw, 64px); }
.caret { display: inline-block; width: .42em; height: .82em; margin-left: .1em; vertical-align: -0.04em; background: var(--mark); border-radius: 2px; animation: blink 1.1s steps(1) infinite; }
@keyframes blink { 50% { opacity: 0; } }
@media (prefers-reduced-motion: reduce) { .caret { animation: none; } }

.courses { display: grid; gap: 24px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 440px), 1fr)); align-items: start; }
.course { --pad: 26px; background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-lg); padding: var(--pad); display: grid; gap: 16px; min-width: 0; overflow: hidden; position: relative; }
.course::before { content: ""; position: absolute; inset: 0 0 auto 0; height: 8px; background: var(--mark); }
.course-head { display: grid; gap: 6px; padding-top: 6px; }
.course h2 { font-size: clamp(30px, 4.6vw, 40px); line-height: 1.05; }
.course h2 a { color: var(--ink); text-decoration: none; }
.course h2 a:hover { text-decoration: underline; text-decoration-color: var(--mark); text-decoration-thickness: 4px; }
.kicker { font-weight: 700; font-size: 17px; }
.course .lead { font-size: 16.5px; }
.course .sample { margin: 4px calc(-1 * var(--pad)) 0; gap: 0; }
.course .sample > .lang { position: absolute; visibility: hidden; }
.course .sample > pre { border-radius: 0; box-shadow: none; padding: 20px var(--pad); white-space: pre-wrap; overflow-wrap: anywhere; font-size: 14px; }
.course .result { margin: 0; border: 0; border-radius: 0; border-bottom: 1px solid var(--line); background: color-mix(in srgb, var(--ok) 7%, var(--surface)); padding: 12px var(--pad) 14px; }
.course .result::before { border-radius: 0; }
.course .result pre { white-space: pre-wrap; overflow-wrap: anywhere; }
.mods { margin: 0; padding: 0; list-style: none; counter-reset: mod; columns: 2; column-gap: 24px; font-size: 15px; }
.mods li { counter-increment: mod; break-inside: avoid; padding: 3px 0; display: flex; gap: 10px; }
.mods li::before { content: counter(mod); font-weight: 800; color: var(--muted); min-width: 1.2em; text-align: right; font-variant-numeric: tabular-nums; }
.mods a { color: var(--ink); text-decoration: none; }
.mods a:hover { color: var(--accent); text-decoration: underline; }
.mods .soon { color: var(--muted); }
.mods .done a::after { content: " ✓"; color: var(--ok); }
@media (max-width: 480px) { .mods { columns: 1; } .course { --pad: 18px; } }
.course-foot { display: grid; gap: 12px; border-top: 1px solid var(--line); padding-top: 16px; }
.meter { height: 8px; border-radius: 4px; background: var(--line); overflow: hidden; }
.meter i { display: block; height: 100%; background: var(--mark); }

.how { gap: 14px; }
.steps { display: grid; gap: 28px; margin-top: 10px; }
.step { display: grid; gap: 12px; min-width: 0; }
.step-n { font-weight: 700; font-size: 18px; display: flex; align-items: center; gap: 12px; }
.step-n .num { display: inline-grid; place-items: center; width: 34px; height: 34px; border-radius: 50%; background: var(--mark); color: var(--on-mark); font-size: 17px; flex: none; }
.pick { display: grid; gap: 12px; margin-top: 4px; }
.pick .note { font-size: 16.5px; }