:root {
  --paper: #f6f3ec; --card: #fffdf8; --ink: #1c2230; --ink2: #4b5466; --muted: #7a8292;
  --line: #e4ddcf; --accent: #0f5f5c; --accent2: #e7f1ef; --gold: #c98a06; --gold2: #fbf1d6;
  --ok: #1d7a46; --mid: #b06d00; --ko: #b3261e; --okbg: #e3f3e8; --kobg: #fbe7e5;
  --serif: 'Fraunces', Georgia, serif; --sans: 'IBM Plex Sans', system-ui, sans-serif; --mono: 'IBM Plex Mono', ui-monospace, monospace;
  --nav: 236px; --r: 12px;
}
@media (prefers-color-scheme: dark) {
  :root { --paper: #12161d; --card: #1a1f28; --ink: #e9e6de; --ink2: #b8bcc6; --muted: #8b92a1; --line: #2c3340;
    --accent: #5cc3b8; --accent2: #1b2e2d; --gold: #f2b84b; --gold2: #2e2716; --okbg: #183022; --kobg: #3a1f1d; --ok: #5fcf8c; --mid: #f0b14a; --ko: #f07a70; }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 16px/1.6 var(--sans); }
a { color: var(--accent); }
h1, h2, h3 { font-family: var(--serif); font-weight: 700; line-height: 1.2; letter-spacing: -.01em; }
h1 { font-size: clamp(1.7rem, 3.4vw, 2.4rem); margin: .2em 0 .4em; }
h2.sec { font-size: 1.3rem; margin: 2rem 0 .8rem; padding-bottom: .3rem; border-bottom: 1px solid var(--line); }
h3 { font-size: 1.08rem; margin: 0 0 .4rem; }
h4 { font-family: var(--serif); font-size: 1.05rem; margin: 1.6rem 0 .6rem; }
.mono, code, pre, textarea.mono { font-family: var(--mono); }
.top { position: sticky; top: 0; z-index: 30; display: flex; align-items: center; gap: .8rem; height: 56px; padding: 0 1rem; background: var(--paper); border-bottom: 1px solid var(--line); }
.brand { display: flex; align-items: center; gap: .55rem; text-decoration: none; color: var(--ink); font-family: var(--serif); font-size: 1.15rem; }
.brand b { color: var(--accent); }
.logo { display: grid; place-items: center; width: 32px; height: 32px; border-radius: 9px; background: var(--accent); color: #f6c453; font-size: 1.15rem; }
.menu { display: none; border: 0; background: none; font-size: 1.4rem; color: var(--ink); cursor: pointer; }
.nav { position: fixed; top: 56px; left: 0; bottom: 0; width: var(--nav); padding: 1rem .7rem; overflow-y: auto; border-right: 1px solid var(--line); background: var(--paper); z-index: 20; }
.nav a { display: block; padding: .45rem .7rem; border-radius: 8px; color: var(--ink2); text-decoration: none; font-weight: 500; font-size: .95rem; }
.nav a:hover { background: var(--accent2); color: var(--ink); }
.nav a.active { background: var(--accent); color: #fff; }
.nav-sep { margin: 1rem .7rem .3rem; font-size: .72rem; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); }
.main { margin-left: var(--nav); padding: 1.6rem clamp(1rem, 4vw, 3rem) 3rem; max-width: calc(1080px + var(--nav)); }
.foot { margin-left: var(--nav); padding: 1.5rem clamp(1rem, 4vw, 3rem); color: var(--muted); font-size: .8rem; border-top: 1px solid var(--line); }
@media (max-width: 860px) {
  .menu { display: block; }
  .nav { transform: translateX(-100%); transition: transform .2s; box-shadow: 0 10px 30px rgba(0,0,0,.15); }
  body.nav-open .nav { transform: none; }
  .main, .foot { margin-left: 0; }
}
.hero { padding: 1.2rem 0 1.4rem; }
.hero h1 { font-size: clamp(2rem, 5vw, 3.2rem); max-width: 18ch; }
.hero h1 em { color: var(--accent); font-style: italic; }
.kicker { text-transform: uppercase; letter-spacing: .09em; font-size: .75rem; color: var(--gold); font-weight: 600; margin: 0; }
.lead { font-size: 1.08rem; color: var(--ink2); max-width: 68ch; }
.hero-cta, .row { display: flex; flex-wrap: wrap; gap: .6rem; align-items: center; margin: .8rem 0; }
.grid { display: grid; gap: 1rem; margin-bottom: 1rem; }
.grid.two { grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); }
.grid.three { grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); }
.grid.stats { grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); }
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--r); padding: 1.1rem 1.2rem; margin-bottom: 1rem; }
.grid > .card { margin-bottom: 0; }
.card.link { text-decoration: none; color: var(--ink); transition: transform .12s, border-color .12s; display: block; }
.card.link:hover { transform: translateY(-2px); border-color: var(--accent); }
.card.link p { color: var(--ink2); margin: 0; font-size: .93rem; }
.card.accent { border-left: 4px solid var(--accent); background: linear-gradient(90deg, var(--accent2), var(--card) 40%); }
.card.question { border-left: 4px solid var(--gold); }
.stat b { display: block; font-family: var(--serif); font-size: 2rem; color: var(--accent); }
.stat span { color: var(--muted); font-size: .88rem; }
.btn { display: inline-flex; align-items: center; gap: .3rem; padding: .5rem .95rem; border-radius: 9px; border: 1px solid var(--line); background: var(--card); color: var(--ink); font: 500 .93rem var(--sans); text-decoration: none; cursor: pointer; }
.btn:hover { border-color: var(--accent); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.primary:hover { filter: brightness(1.08); }
.btn.ghost { background: transparent; }
.btn.small { padding: .3rem .7rem; font-size: .85rem; }
.btn:disabled { opacity: .45; cursor: default; }
.pill { display: inline-block; padding: .05rem .55rem; border-radius: 99px; font-size: .74rem; background: var(--accent2); color: var(--accent); font-weight: 600; margin-right: .3rem; }
.pill.ok { background: var(--okbg); color: var(--ok); } .pill.mid { background: var(--gold2); color: var(--mid); } .pill.ko { background: var(--kobg); color: var(--ko); }
.ok { color: var(--ok); } .mid { color: var(--mid); } .ko { color: var(--ko); }
.muted { color: var(--muted); } .small { font-size: .86rem; } .dim { opacity: .3; } .hidden { display: none !important; }
.warn { background: var(--gold2); border: 1px solid #ecd59a; border-radius: 10px; padding: .6rem .9rem; color: var(--ink); }
.info { background: var(--accent2); border-radius: 10px; padding: .6rem .9rem; }
.crumbs { margin: 0; font-size: .85rem; color: var(--muted); }
.crumbs a { color: var(--muted); }
.prose { max-width: 78ch; }
.prose table, .card table:not(.tableau) { border-collapse: collapse; margin: .8rem 0; font-size: .93rem; }
.prose th, .prose td, .card table:not(.tableau) td, .card table:not(.tableau) th { border: 1px solid var(--line); padding: .35rem .6rem; text-align: left; }
pre { background: #1e2533; color: #e7ecf3; padding: .9rem 1rem; border-radius: 10px; overflow-x: auto; font-size: .86rem; line-height: 1.5; }
:not(pre) > code { background: var(--accent2); padding: .05rem .3rem; border-radius: 5px; font-size: .88em; }
mjx-container[display="true"] { overflow-x: auto; overflow-y: hidden; padding: .2rem 0; }
.tabs { display: flex; gap: .3rem; border-bottom: 1px solid var(--line); margin-bottom: 1.2rem; overflow-x: auto; }
.tab { border: 0; background: none; padding: .6rem .9rem; font: 500 .95rem var(--sans); color: var(--ink2); cursor: pointer; border-bottom: 3px solid transparent; white-space: nowrap; }
.tab.on { color: var(--accent); border-bottom-color: var(--accent); }
.pager { display: flex; justify-content: space-between; gap: 1rem; margin-top: 2rem; flex-wrap: wrap; }
.flash { position: relative; min-height: 220px; perspective: 1200px; cursor: pointer; max-width: 640px; }
.flash .face { position: absolute; inset: 0; display: grid; place-items: center; text-align: center; padding: 1.5rem; border-radius: 16px; border: 1px solid var(--line); background: var(--card); backface-visibility: hidden; transition: transform .45s; font-size: 1.08rem; overflow: auto; }
.flash .back { transform: rotateY(180deg); background: var(--accent2); }
.flash.flip .front { transform: rotateY(-180deg); } .flash.flip .back { transform: rotateY(0); }
.flash-ctl { display: flex; gap: .6rem; align-items: center; margin: .9rem 0; }
.qn { text-transform: uppercase; letter-spacing: .07em; font-size: .72rem; color: var(--gold); font-weight: 600; margin-bottom: .3rem; }
.opts { display: grid; gap: .45rem; margin-top: .6rem; }
.opt { text-align: left; padding: .55rem .8rem; border-radius: 9px; border: 1px solid var(--line); background: var(--card); color: var(--ink); font: .95rem var(--sans); cursor: pointer; }
.opt p { margin: 0; }
.opt:hover { border-color: var(--accent); }
.opt.sel { border-color: var(--accent); background: var(--accent2); }
.opt.right { background: var(--okbg); border-color: var(--ok); } .opt.wrong { background: var(--kobg); border-color: var(--ko); } .opt.dim { opacity: .55; }
.answer .opts { grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); }
.expl { margin-top: .6rem; font-size: .93rem; }
.filters { display: flex; flex-wrap: wrap; gap: .8rem; align-items: end; margin: 1rem 0; }
.filters label, .row label { display: flex; flex-direction: column; font-size: .8rem; color: var(--muted); gap: .2rem; }
label.inline { flex-direction: row; align-items: center; gap: .4rem; font-size: .9rem; }
select, input, textarea { font: .95rem var(--sans); padding: .45rem .6rem; border: 1px solid var(--line); border-radius: 8px; background: var(--card); color: var(--ink); }
textarea { width: 100%; resize: vertical; }
select { max-width: 100%; }
input.num { width: 7.5rem; } input.wide { width: 16rem; } #addin { width: 100%; }
.lbl2 { display: block; font-size: .84rem; color: var(--muted); margin: .6rem 0 .25rem; }
.ex-meta { display: flex; align-items: center; gap: .3rem; flex-wrap: wrap; font-size: .75rem; color: var(--gold); margin-bottom: .4rem; }
.helpbar, .donebar, .qhelp, .submitbar { display: flex; flex-wrap: wrap; gap: .5rem; align-items: center; margin: 1rem 0; }
.donebar { border-top: 1px solid var(--line); padding-top: 1rem; }
.hint { background: var(--gold2); border-radius: 10px; padding: .55rem .9rem; margin: .5rem 0; }
.hint p { margin: .2rem 0; }
.step { border: 1px solid var(--line); border-radius: var(--r); background: var(--card); margin: .8rem 0; overflow: hidden; }
.step-h { display: flex; align-items: center; gap: .55rem; padding: .5rem .9rem; background: var(--accent2); font-weight: 600; font-size: .92rem; }
.step-n { display: grid; place-items: center; width: 24px; height: 24px; border-radius: 50%; background: var(--accent); color: #fff; font-size: .78rem; }
.step-c { padding: .2rem 1rem; }
.tag { font-size: .7rem; background: var(--gold2); color: var(--mid); padding: .05rem .4rem; border-radius: 5px; }
.tab-wrap { overflow-x: auto; padding: 0 1rem .6rem; }
.tableau { border-collapse: collapse; font-family: var(--mono); font-size: .9rem; margin: .4rem 0; }
.tableau th, .tableau td { border: 1px solid var(--line); padding: .3rem .6rem; text-align: center; min-width: 3.1rem; }
.tableau th { background: var(--paper); font-weight: 500; }
.tableau .lbl { background: var(--paper); font-weight: 600; }
.tableau .rhs { border-left: 2px solid var(--ink2); }
.tableau .zrow td { border-bottom: 2px solid var(--ink2); background: color-mix(in srgb, var(--gold2) 60%, transparent); }
.tableau .pc { background: color-mix(in srgb, var(--accent2) 85%, transparent); }
.tableau .pr td { background: color-mix(in srgb, var(--accent2) 85%, transparent); }
.tableau td.pivot { background: var(--accent); color: #fff; font-weight: 700; }
.tableau .neg { color: var(--ko); font-weight: 600; }
.tableau tr.added td { box-shadow: inset 0 0 0 9999px color-mix(in srgb, var(--kobg) 50%, transparent); }
.tableau .ratio { color: var(--muted); border-left: 2px dashed var(--line); }
.tableau .ratio.min { color: var(--accent); font-weight: 700; }
.fr { display: inline-flex; flex-direction: column; align-items: center; vertical-align: middle; line-height: 1; font-size: .82em; }
.fr sup, .fr sub { font-size: 1em; vertical-align: baseline; position: static; }
.fr > span { display: none; } .fr sup { border-bottom: 1px solid currentColor; padding: 0 .1em; }
.basic-sol { padding: 0 1rem .8rem; font-size: .86rem; color: var(--ink2); }
table.rules td { padding: .25rem .7rem; }
.svg-scroll { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--r); background: var(--card); padding: .5rem; }
.bbtree .edge { stroke: var(--muted); stroke-width: 1.5; }
.bbtree .elab { font: 12px var(--mono); fill: var(--ink2); }
.bbnode rect { fill: var(--card); stroke: var(--ink2); stroke-width: 1.5; }
.bbnode .nname { font: 600 13px var(--sans); fill: var(--ink); } .bbnode .nval { font: 12px var(--mono); fill: var(--ink2); }
.bbnode.exp rect { fill: var(--accent2); stroke: var(--accent); }
.bbnode.int rect { fill: var(--okbg); stroke: var(--ok); }
.bbnode.cut rect { fill: var(--gold2); stroke: var(--mid); stroke-dasharray: 4 3; }
.bbnode.inf rect { fill: var(--kobg); stroke: var(--ko); stroke-dasharray: 2 3; }
.bbnode.best rect { stroke-width: 3.5; stroke: var(--ok); }
.legend { display: flex; flex-wrap: wrap; gap: .5rem; font-size: .8rem; margin: .5rem 0; align-items: center; }
.lg { padding: .05rem .5rem; border-radius: 6px; border: 1px solid; }
.lg.exp { background: var(--accent2); border-color: var(--accent); } .lg.int { background: var(--okbg); border-color: var(--ok); } .lg.cut { background: var(--gold2); border-color: var(--mid); border-style: dashed; } .lg.inf { background: var(--kobg); border-color: var(--ko); border-style: dotted; } .lg.best { border-width: 3px; border-color: var(--ok); }
.bblog li { margin: .45rem 0; } .bblog p { margin: .1rem 0; }
.flow .fe { stroke: var(--muted); stroke-width: 1.6; } .flow .fe.used { stroke: var(--accent); stroke-width: 2.4; } .flow .fe.cut { stroke: var(--ko); stroke-width: 3; }
.flow .arh { fill: var(--muted); }
.flow .fl { font: 12px var(--mono); fill: var(--ink); paint-order: stroke; stroke: var(--card); stroke-width: 4px; } .flow .fl.sat { fill: var(--ko); font-weight: 700; }
.fn circle { fill: var(--card); stroke: var(--ink2); stroke-width: 1.6; } .fn.inS circle { fill: var(--accent2); stroke: var(--accent); } .fn text { font: 600 13px var(--sans); fill: var(--ink); }
.exq-h { display: flex; align-items: center; gap: .6rem; flex-wrap: wrap; margin-bottom: .4rem; }
.qnum { font-family: var(--serif); font-weight: 700; font-size: 1.15rem; color: var(--accent); }
.qtitle { font-weight: 600; } .pts { margin-left: auto; font-size: .8rem; color: var(--muted); }
.notes { min-height: 90px; margin: .6rem 0; font-family: var(--mono); font-size: .88rem; }
.answer { border-top: 1px dashed var(--line); padding-top: .7rem; margin-top: .4rem; }
.answer label { display: inline-flex; flex-direction: column; margin-right: 1rem; font-size: .8rem; color: var(--muted); }
.chk { margin-left: .6rem; }
.qsol { border-top: 2px solid var(--accent); margin-top: 1rem; padding-top: .6rem; }
.checklist { list-style: none; padding: 0; } .checklist li { margin: .3rem 0; } .checklist label { display: flex; gap: .5rem; align-items: flex-start; cursor: pointer; } .checklist input { margin-top: .35rem; }
.checklist p { margin: 0; }
details.reveal summary { cursor: pointer; font-weight: 600; color: var(--accent); padding: .6rem 0; }
.exam-top { position: sticky; top: 56px; z-index: 10; display: flex; justify-content: space-between; align-items: center; gap: 1rem; background: var(--paper); padding: .4rem 0; border-bottom: 1px solid var(--line); }
.exam-top h1 { font-size: 1.4rem; margin: 0; }
.timer { font: 600 1.6rem var(--mono); padding: .3rem .8rem; border-radius: 10px; background: var(--card); border: 1px solid var(--line); }
.timer.soon { color: var(--mid); border-color: var(--mid); } .timer.late { color: #fff; background: var(--ko); }
.gradetab { width: 100%; border-collapse: collapse; } .gradetab td, .gradetab th { border-bottom: 1px solid var(--line); padding: .45rem .5rem; text-align: left; }
.final-grade { display: flex; align-items: baseline; gap: 1rem; margin: 1rem 0 .3rem; } .final-grade b { font: 700 2.4rem var(--serif); }
.pattern { border-collapse: collapse; width: 100%; font-size: .9rem; background: var(--card); } .pattern td, .pattern th { border: 1px solid var(--line); padding: .45rem .6rem; } .pattern th { background: var(--accent2); text-align: left; }
.sorttab td { padding: .25rem .5rem; vertical-align: middle; } .cell { display: inline-grid; place-items: center; min-width: 2.2rem; height: 2.2rem; margin: 1px; border: 1px solid var(--line); border-radius: 6px; font: 500 .9rem var(--mono); background: var(--card); }
.cell.done { background: var(--okbg); border-color: var(--ok); } .cell.hl { background: var(--accent); color: #fff; border-color: var(--accent); }
.oral li { margin: .4rem 0; } .oral-timer { font: 600 2rem var(--mono); color: var(--accent); margin: .6rem 0; } .oral-timer.late { color: var(--ko); }
.bars { display: grid; gap: .4rem; } .bar { display: grid; grid-template-columns: 220px 1fr 50px; gap: .7rem; align-items: center; text-decoration: none; color: var(--ink); font-size: .9rem; }
.bar i { height: 10px; border-radius: 6px; background: var(--line); display: block; } .bar i.ok { background: var(--ok); } .bar i.mid { background: var(--mid); } .bar i.ko { background: var(--ko); }
@media (max-width: 560px) { .bar { grid-template-columns: 1fr 70px 40px; } .exam-top h1 { font-size: 1.1rem; } .timer { font-size: 1.2rem; } }
@media print { .nav, .top, .helpbar, .qhelp, .submitbar, .notes { display: none; } .main { margin: 0; } }
.answer .checklist label { display: flex; flex-direction: row; font-size: .95rem; color: var(--ink); margin: 0; }
.answer label { white-space: nowrap; }
.hint { display: flex; gap: .5rem; align-items: flex-start; } .hint p:first-child { margin-top: .2rem; }

/* ---------- Piano di studio ---------- */
.pbar { height: 12px; border-radius: 99px; background: var(--line); overflow: hidden; margin: .4rem 0 .2rem; }
.pbar i { display: block; height: 100%; background: var(--accent); border-radius: 99px; transition: width .3s; }
.plist { list-style: none; padding: 0; margin: .4rem 0; display: grid; gap: .5rem; }
.ptask { display: flex; gap: .7rem; align-items: flex-start; background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: .6rem .8rem; }
.ptask input[type=checkbox] { width: 1.15rem; height: 1.15rem; margin-top: .2rem; accent-color: var(--accent); flex: none; cursor: pointer; }
.ptask a { font-weight: 600; text-decoration: none; }
.ptask a:hover { text-decoration: underline; }
.ptask.done { opacity: .6; } .ptask.done a { text-decoration: line-through; }
.pwhy { font-size: .85rem; color: var(--ink2); margin-top: .2rem; }
.plist.compact { gap: .3rem; } .plist.compact .ptask { padding: .35rem .6rem; font-size: .92rem; }
.pcal { display: grid; gap: .35rem; }
.pday { border: 1px solid var(--line); border-radius: 10px; background: var(--card); padding: .1rem .8rem; }
.pday summary { cursor: pointer; display: grid; grid-template-columns: 110px 1fr auto; gap: .6rem; padding: .45rem 0; align-items: center; }
.pday.today { border-color: var(--accent); box-shadow: 0 0 0 2px var(--accent2); }
.pday.past.ok summary b { color: var(--ok); } .pday.past.ko summary b { color: var(--ko); }
.pday.exam { padding: .6rem .8rem; border-color: var(--gold); background: var(--gold2); }
.ptag { font-size: .82rem; color: var(--muted); }
.pform { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 1rem; }
.pform label { display: flex; flex-direction: column; gap: .3rem; font-size: .85rem; color: var(--muted); }
.pform select, .pform input { font: 500 1rem var(--sans); padding: .45rem .6rem; border-radius: 9px; border: 1px solid var(--line); background: var(--paper); color: var(--ink); }
.prest { border: 0; padding: 0; margin: 1rem 0 0; display: flex; flex-wrap: wrap; gap: .4rem .9rem; }
.prest legend { font-size: .85rem; color: var(--muted); margin-bottom: .3rem; }
.prest label { display: flex; gap: .3rem; align-items: center; }
.planback { margin: 0 0 .5rem; font-size: .9rem; }
@media (max-width: 600px) { .pday summary { grid-template-columns: 90px 1fr auto; font-size: .9rem; } }