:root{
  --bg:#f5f6fb; --surface:#ffffff; --surface2:#eef0f8; --text:#1b2133; --muted:#69728a; --line:#e0e4f0;
  --accent:#4f6bff; --accent-ink:#ffffff; --accent-soft:#e6ebff;
  --again:#e5484d; --hard:#f08c2e; --good:#2fa66a; --easy:#3a82f7; --fire:#ff7a1a;
  --radius:14px; --shadow:0 1px 2px rgba(20,30,60,.06),0 6px 20px rgba(20,30,60,.06);
}
@media (prefers-color-scheme: dark){
  :root{ --bg:#0f1220; --surface:#171b2d; --surface2:#1f2438; --text:#e9ecf7; --muted:#8e97b3; --line:#283049;
    --accent:#7189ff; --accent-ink:#0b1030; --accent-soft:#222b55; --shadow:0 1px 2px rgba(0,0,0,.3),0 6px 20px rgba(0,0,0,.25); }
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;font-family:system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;background:var(--bg);color:var(--text);line-height:1.5}
h1,h2,h3{line-height:1.25;margin:0}
h2{font-size:1.1rem;margin:28px 0 12px}
a{color:var(--accent)}
.boot{text-align:center;margin-top:30vh;color:var(--muted)}
.muted{color:var(--muted)}.small{font-size:.85rem}
.hidden{display:none!important}
.row{display:flex;gap:10px;align-items:center;flex-wrap:wrap}
.grow{flex:1}
.spacer{flex:1}

button,.btn,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;background:var(--accent);color:var(--accent-ink);border:0;border-radius:10px;padding:9px 16px;font-weight:600;text-decoration:none}
.btn:hover{filter:brightness(1.08)}
.btn:disabled{opacity:.55;cursor:not-allowed}
.btn.ghost{background:transparent;color:var(--text);border:1px solid var(--line)}
.btn.ghost:hover{background:var(--surface2)}
.btn.danger{background:var(--again);color:#fff}
.btn.small{padding:5px 10px;font-size:.85rem;font-weight:500}
.btn.icon{padding:5px 9px}
input,select,textarea{width:100%;background:var(--surface);border:1px solid var(--line);border-radius:10px;padding:10px 12px}
input:focus,select:focus,textarea:focus{outline:2px solid var(--accent);outline-offset:-1px}
textarea{resize:vertical;min-height:90px}
label.field{display:block;margin:12px 0 4px;font-size:.88rem;font-weight:600}

/* ---------- login ---------- */
.auth-wrap{min-height:100vh;display:grid;place-items:center;padding:20px}
.auth-card{width:min(420px,100%);background:var(--surface);border:1px solid var(--line);border-radius:20px;padding:28px;box-shadow:var(--shadow)}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;font-size:1.2rem}
.brand .logo{display:grid;place-items:center;width:36px;height:36px;border-radius:10px;background:var(--accent);color:var(--accent-ink);font-size:1.1rem}
.tabs{display:flex;background:var(--surface2);border-radius:10px;padding:4px;margin:20px 0 6px}
.tabs button{flex:1;border:0;background:transparent;padding:8px;border-radius:8px;color:var(--muted);font-weight:600}
.tabs button.active{background:var(--surface);color:var(--text);box-shadow:var(--shadow)}
.divider{display:flex;align-items:center;gap:10px;color:var(--muted);font-size:.85rem;margin:16px 0}
.divider::before,.divider::after{content:"";flex:1;height:1px;background:var(--line)}
.btn.google{width:100%;background:var(--surface);color:var(--text);border:1px solid var(--line)}
.msg{margin-top:12px;font-size:.9rem;padding:10px 12px;border-radius:10px}
.msg.err{background:rgba(229,72,77,.12);color:var(--again)}
.msg.ok{background:rgba(47,166,106,.14);color:var(--good)}
.setup{max-width:640px;margin:8vh auto;padding:0 20px}
.setup code,.setup pre{background:var(--surface2);border-radius:8px;padding:2px 6px}
.setup pre{padding:12px;overflow:auto}

/* ---------- topo ---------- */
.top{position:sticky;top:0;z-index:20;background:color-mix(in srgb,var(--surface) 92%,transparent);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
.top-in{max-width:1100px;margin:0 auto;padding:10px 16px;display:flex;align-items:center;gap:14px;flex-wrap:wrap}
.nav{display:flex;gap:4px;overflow-x:auto}
.nav a{padding:7px 12px;border-radius:9px;color:var(--muted);text-decoration:none;font-weight:600;white-space:nowrap}
.nav a:hover{background:var(--surface2)}
.nav a.active{background:var(--accent-soft);color:var(--accent)}
.nav a.soon{opacity:.55;pointer-events:none}
.nav a.soon::after{content:"em breve";margin-left:6px;font-size:.62rem;text-transform:uppercase;letter-spacing:.04em;background:var(--surface2);padding:2px 6px;border-radius:99px}
.chip{display:flex;align-items:center;gap:8px;padding:5px 6px 5px 12px;background:var(--surface2);border-radius:99px;font-weight:600;font-size:.9rem}
.streak{color:var(--fire);font-weight:800}
.avatar{display:grid;place-items:center;width:30px;height:30px;border-radius:50%;background:var(--accent);color:var(--accent-ink);font-weight:800;font-size:.85rem}
main{max-width:1100px;margin:0 auto;padding:20px 16px 60px}

/* ---------- início ---------- */
.hero{display:flex;gap:16px;align-items:center;flex-wrap:wrap;background:linear-gradient(135deg,var(--accent),#8b5cf6);color:#fff;border-radius:20px;padding:22px 24px;box-shadow:var(--shadow)}
.hero h1{font-size:1.4rem}
.hero p{margin:4px 0 0;opacity:.9}
.hero .btn{background:#fff;color:#2d3a8c}
.stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:12px;margin-top:16px}
.stat{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:14px 16px;box-shadow:var(--shadow)}
.stat b{display:block;font-size:1.8rem;line-height:1.2}
.stat small{color:var(--muted)}
.cols{display:grid;grid-template-columns:1fr 1fr;gap:16px}
@media(max-width:760px){.cols{grid-template-columns:1fr}}
.panel{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:16px;box-shadow:var(--shadow)}
.panel h3{font-size:1rem;margin-bottom:10px}
.rank{list-style:none;margin:0;padding:0}
.rank li{display:flex;gap:10px;align-items:center;padding:8px 0;border-top:1px solid var(--line)}
.rank li:first-child{border-top:0}
.rank a{flex:1;color:inherit;text-decoration:none;min-width:0}
.rank a span{display:block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.pill{font-size:.8rem;font-weight:700;padding:2px 9px;border-radius:99px;background:var(--surface2)}
.pill.bad{background:rgba(229,72,77,.14);color:var(--again)}
.pill.ok{background:rgba(47,166,106,.15);color:var(--good)}
.heat{display:grid;grid-auto-flow:column;grid-template-rows:repeat(7,14px);gap:4px;overflow-x:auto;padding-bottom:4px}
.heat i{width:14px;height:14px;border-radius:4px;background:var(--surface2)}
.heat i.l1{background:color-mix(in srgb,var(--accent) 30%,var(--surface2))}
.heat i.l2{background:color-mix(in srgb,var(--accent) 55%,var(--surface2))}
.heat i.l3{background:color-mix(in srgb,var(--accent) 80%,var(--surface2))}
.heat i.l4{background:var(--accent)}
.empty{text-align:center;color:var(--muted);padding:26px 10px}

/* ---------- flashcards ---------- */
.split{display:grid;grid-template-columns:300px 1fr;gap:16px;align-items:start}
@media(max-width:820px){.split{grid-template-columns:1fr}}
.tree{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:10px;box-shadow:var(--shadow)}
.tree ul{list-style:none;margin:0;padding:0}
.tree ul ul{margin-left:14px;border-left:1px dashed var(--line);padding-left:6px}
.node{display:flex;align-items:center;gap:4px;border-radius:9px;padding:3px 4px}
.node:hover{background:var(--surface2)}
.node.sel{background:var(--accent-soft)}
.node .tog{width:22px;height:22px;border:0;background:transparent;color:var(--muted);border-radius:6px;flex:none}
.node .tog:hover{background:var(--line)}
.node a{flex:1;min-width:0;display:flex;gap:6px;align-items:center;color:inherit;text-decoration:none;padding:4px 2px}
.node a .nm{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.node .cnt{margin-left:auto;font-size:.75rem;color:var(--muted);white-space:nowrap}
.node .cnt b{color:var(--accent)}
.crumbs{font-size:.88rem;color:var(--muted);margin-bottom:6px}
.fhead{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin-bottom:14px}
.fhead h2{margin:0;font-size:1.35rem}
.cardrow{display:flex;gap:10px;align-items:flex-start;background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:10px 12px;margin:8px 0}
.cardrow .txt{flex:1;min-width:0}
.cardrow .q{font-weight:600;white-space:pre-wrap;word-break:break-word}
.cardrow .a{color:var(--muted);font-size:.9rem;white-space:pre-wrap;word-break:break-word;margin-top:2px;max-height:4.5em;overflow:hidden}
.cardrow .meta{font-size:.75rem;color:var(--muted);margin-top:4px}

/* ---------- estudo ---------- */
.study{max-width:720px;margin:0 auto}
.study-top{display:flex;align-items:center;gap:12px;margin-bottom:12px}
.progress{height:8px;background:var(--surface2);border-radius:99px;overflow:hidden;flex:1}
.progress i{display:block;height:100%;background:var(--accent);transition:width .25s}
.flash{background:var(--surface);border:1px solid var(--line);border-radius:22px;min-height:260px;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:28px;text-align:center;box-shadow:var(--shadow);cursor:pointer}
.flash .side{font-size:.72rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);margin-bottom:10px}
.flash .content{font-size:1.35rem;white-space:pre-wrap;word-break:break-word}
.flash.back{border-color:var(--accent)}
.answers{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-top:14px}
@media(max-width:520px){.answers{grid-template-columns:repeat(2,1fr)}}
.ans{border:0;border-radius:12px;padding:10px 6px;color:#fff;font-weight:700;display:flex;flex-direction:column;gap:2px;align-items:center}
.ans small{font-weight:500;opacity:.9}
.ans.again{background:var(--again)}.ans.hard{background:var(--hard)}.ans.good{background:var(--good)}.ans.easy{background:var(--easy)}
.ans:hover{filter:brightness(1.07)}
.doubt{margin-top:16px}
.video{margin-top:10px;position:relative;padding-top:56.25%;border-radius:14px;overflow:hidden;background:#000}
.video iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.done{text-align:center;padding:40px 10px}
.done .big{font-size:3rem}

/* ---------- janelas e avisos ---------- */
.overlay{position:fixed;inset:0;background:rgba(10,14,30,.55);display:grid;place-items:center;padding:16px;z-index:50}
.modal{width:min(560px,100%);max-height:92vh;overflow:auto;background:var(--surface);border-radius:18px;padding:22px;box-shadow:0 20px 60px rgba(0,0,0,.35)}
.modal h3{font-size:1.1rem;margin-bottom:4px}
.modal .actions{display:flex;gap:8px;justify-content:flex-end;margin-top:18px;flex-wrap:wrap}
#toasts{position:fixed;left:50%;bottom:20px;transform:translateX(-50%);display:flex;flex-direction:column;gap:8px;z-index:80}
.toast{background:var(--text);color:var(--bg);padding:10px 16px;border-radius:10px;box-shadow:var(--shadow);font-size:.9rem}
.toast.err{background:var(--again);color:#fff}