:root{
  --fs: 16px;
  --bg:#f4f5f9; --panel:#ffffff; --panel2:#fbfbfd; --text:#141821; --muted:#6b7280;
  --border:#e4e7ef; --accent:#d81e3f; --accent2:#a3122e; --soft:#ffe9ee;
  --ok:#128a4a; --ok-soft:#e6f7ee; --bad:#c02b2b; --bad-soft:#fdeaea;
  --warn:#b06a00; --warn-soft:#fff5e0;
  --shadow:0 8px 26px rgba(20,24,33,.07); --r:1rem;
}
body.dark{
  --bg:#0d1015; --panel:#161b23; --panel2:#12161d; --text:#e8ecf4; --muted:#9aa4b8;
  --border:#242c3a; --accent:#ff5773; --accent2:#ff8fa3; --soft:#2a1620;
  --ok:#3ddc84; --ok-soft:#12291d; --bad:#ff6b6b; --bad-soft:#2b1616;
  --warn:#ffc46b; --warn-soft:#2b2110;
  --shadow:0 8px 26px rgba(0,0,0,.4);
}
html{font-size:var(--fs)}
*,*::before,*::after{box-sizing:border-box}
body{margin:0;font-family:system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif;
  background:var(--bg);color:var(--text);-webkit-font-smoothing:antialiased;
  transition:background .2s,color .2s;overflow-wrap:anywhere}
button{font:inherit}
#app{max-width:78rem;margin:0 auto;padding:0 1rem 4rem}

/* topbar */
.topbar{display:flex;align-items:center;justify-content:space-between;gap:.75rem;
  padding:1.1rem 0 1rem;flex-wrap:wrap}
.brand{display:flex;align-items:center;gap:.75rem;min-width:0}
.flag{font-size:1.9rem;line-height:1}
.brand h1{font-size:1.15rem;margin:0;letter-spacing:-.02em;white-space:nowrap}
.brand p{margin:.1rem 0 0;font-size:.72rem;color:var(--muted);font-weight:600}
.nav{display:flex;gap:.25rem;background:var(--panel);border:1px solid var(--border);
  border-radius:999px;padding:.2rem}
.nav button{border:0;background:transparent;color:var(--muted);padding:.45rem .95rem;
  border-radius:999px;font-size:.82rem;font-weight:800;cursor:pointer}
.nav button.active{background:var(--accent);color:#fff}
.controls{display:flex;align-items:center;gap:.4rem}
.seg{display:inline-flex;background:var(--panel);border:1px solid var(--border);
  border-radius:999px;padding:.15rem;gap:.1rem}
.seg button{border:0;background:transparent;color:var(--muted);padding:.4rem .8rem;
  border-radius:999px;font-size:.75rem;font-weight:800;cursor:pointer}
.seg button.active{background:var(--accent);color:#fff}
.icon-btn{width:2.3rem;height:2.3rem;border-radius:.7rem;border:1px solid var(--border);
  background:var(--panel);color:var(--text);font-size:1rem;cursor:pointer;
  display:grid;place-items:center}
.icon-btn:hover{border-color:var(--accent);color:var(--accent)}

/* layout */
.layout{display:grid;grid-template-columns:17rem 1fr;gap:1.2rem;align-items:start}
@media(max-width:880px){.layout{grid-template-columns:1fr}}

/* sidebar */
.sidebar{background:var(--panel);border:1px solid var(--border);border-radius:var(--r);
  overflow:hidden;position:sticky;top:1rem;box-shadow:var(--shadow)}
.side-head{display:flex;align-items:center;justify-content:space-between;
  padding:.8rem 1rem;border-bottom:1px solid var(--border);font-size:.72rem;
  font-weight:800;text-transform:uppercase;letter-spacing:.08em;color:var(--muted)}
.side-count{background:var(--soft);color:var(--accent);padding:.1rem .55rem;
  border-radius:99px;font-size:.7rem;letter-spacing:0}
.side-scroll{max-height:calc(100vh - 9rem);overflow-y:auto;padding:.35rem}
.side-level{padding:.85rem .6rem .35rem;font-size:.7rem;font-weight:800;
  letter-spacing:.09em;text-transform:uppercase;color:var(--accent);
  position:sticky;top:0;background:var(--panel);z-index:2}
.side-item{display:flex;align-items:center;gap:.5rem;width:100%;text-align:left;
  border:0;background:transparent;color:var(--text);padding:.45rem .6rem;
  border-radius:.6rem;cursor:pointer;font-size:.8rem;line-height:1.3}
.side-item:hover{background:var(--panel2)}
.side-item.active{background:var(--accent);color:#fff}
.side-item.active .si-n{background:rgba(255,255,255,.22);color:#fff;border-color:transparent}
.si-n{flex:0 0 auto;min-width:1.6rem;height:1.4rem;border-radius:.4rem;
  background:var(--panel2);color:var(--muted);font-size:.7rem;font-weight:800;
  display:grid;place-items:center;border:1px solid var(--border)}
.si-t{flex:1;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;font-weight:600}
.si-ok{color:var(--ok);font-weight:900;font-size:.8rem}
.side-item.active .si-ok{color:#fff}

/* lesson */
.content{min-width:0}
.lesson{background:var(--panel);border:1px solid var(--border);border-radius:var(--r);
  padding:1.6rem 1.7rem 1.9rem;box-shadow:var(--shadow)}
.lesson-top{display:flex;align-items:center;justify-content:space-between;
  gap:.6rem;flex-wrap:wrap;margin-bottom:.6rem}
.lesson-meta{display:flex;align-items:center;gap:.55rem}
.badge{background:var(--accent);color:#fff;font-size:.7rem;font-weight:900;
  padding:.2rem .55rem;border-radius:.45rem;letter-spacing:.04em}
.lnum{font-size:.75rem;font-weight:800;color:var(--muted);text-transform:uppercase;
  letter-spacing:.07em}
.tag-done{background:var(--ok-soft);color:var(--ok);font-size:.72rem;font-weight:800;
  padding:.25rem .7rem;border-radius:99px}
.lesson-title{font-size:clamp(1.35rem,3.6vw,1.95rem);margin:0 0 .35rem;
  letter-spacing:-.025em;line-height:1.2}
.lesson-focus{margin:0 0 1.3rem;color:var(--muted);font-size:.9rem;line-height:1.5;font-weight:600}

.para{font-size:.95rem;line-height:1.65;margin:0 0 1.2rem}
.blk{margin:0 0 1.6rem}
.blk-h{font-size:.78rem;font-weight:900;text-transform:uppercase;letter-spacing:.09em;
  color:var(--accent);margin:0 0 .7rem}
.tip{display:flex;gap:.7rem;background:var(--warn-soft);border:1px solid var(--warn);
  border-radius:.8rem;padding:.85rem 1rem;margin:0 0 1.4rem;font-size:.88rem;line-height:1.6}
.tip-ico{font-size:1.05rem;line-height:1.3}

.vocab{display:flex;flex-direction:column;gap:.35rem}
.vrow{display:flex;align-items:center;gap:.85rem;background:var(--panel2);
  border:1px solid var(--border);border-radius:.75rem;padding:.65rem .85rem;
  cursor:pointer;text-align:left;color:var(--text);width:100%}
.vrow:hover{border-color:var(--accent);background:var(--soft)}
.vpl{font-weight:800;font-size:.92rem;flex:1;min-width:0}
.vtr{color:var(--muted);font-size:.85rem;text-align:right;flex:1;min-width:0;font-weight:600}
.vspk{font-size:.78rem;opacity:.4}
.vrow:hover .vspk{opacity:1}
@media(max-width:560px){
  .vrow{flex-wrap:wrap;gap:.2rem}
  .vtr{text-align:left;flex-basis:100%;order:3}
  .vspk{order:2}
}

.tbl-wrap{overflow-x:auto;border:1px solid var(--border);border-radius:.75rem}
.tbl{width:100%;border-collapse:collapse;font-size:.83rem;min-width:26rem}
.tbl th{background:var(--panel2);text-align:left;padding:.65rem .85rem;font-size:.68rem;
  font-weight:900;text-transform:uppercase;letter-spacing:.07em;color:var(--muted);
  border-bottom:1px solid var(--border);white-space:nowrap}
.tbl td{padding:.65rem .85rem;border-bottom:1px solid var(--border);vertical-align:top;line-height:1.45}
.tbl tr:last-child td{border-bottom:0}
.tbl td:first-child{font-weight:800;white-space:nowrap;color:var(--accent)}
.tbl td:last-child{color:var(--muted);font-weight:600}

.gram-body{font-size:.92rem;line-height:1.68;margin-bottom:.7rem}
.gram-body strong{color:var(--accent);font-weight:800}
.ex-list{display:flex;flex-direction:column;gap:.35rem;margin-top:.25rem}
.ex-row{display:flex;align-items:center;gap:.85rem;background:var(--soft);
  border:1px solid transparent;border-radius:.65rem;padding:.6rem .85rem;
  cursor:pointer;text-align:left;color:var(--text);width:100%}
.ex-row:hover{border-color:var(--accent)}
.ex-pl{font-weight:800;font-size:.88rem;flex:1;min-width:0}
.ex-tr{color:var(--muted);font-size:.83rem;text-align:right;flex:1;min-width:0;font-weight:600}
@media(max-width:560px){
  .ex-row{flex-wrap:wrap;gap:.15rem}
  .ex-tr{text-align:left;flex-basis:100%}
}

.dlg{display:flex;flex-direction:column;gap:.55rem}
.dlg-row{display:flex;gap:.6rem;align-items:flex-start}
.dlg-spk{flex:0 0 auto;width:1.55rem;height:1.55rem;border-radius:50%;background:var(--accent);
  color:#fff;font-size:.7rem;font-weight:900;display:grid;place-items:center;margin-top:.2rem}
.dlg-line{flex:1;min-width:0;background:var(--panel2);border:1px solid var(--border);
  border-radius:.7rem;padding:.6rem .85rem;cursor:pointer;text-align:left;color:var(--text)}
.dlg-line:hover{border-color:var(--accent)}
.dlg-pl{display:block;font-weight:800;font-size:.88rem;margin-bottom:.1rem}
.dlg-tr{display:block;color:var(--muted);font-size:.78rem;font-weight:600}

/* exercises */
.exs{display:flex;flex-direction:column;gap:.8rem}
.ex{background:var(--panel2);border:1px solid var(--border);border-radius:.8rem;padding:.9rem 1rem}
.ex-q{font-size:.92rem;font-weight:700;margin-bottom:.7rem;line-height:1.5}
.opts{display:grid;grid-template-columns:1fr 1fr;gap:.45rem}
@media(max-width:560px){.opts{grid-template-columns:1fr}}
.opt{border:1.5px solid var(--border);background:var(--panel);color:var(--text);
  padding:.65rem .85rem;border-radius:.65rem;font-size:.86rem;font-weight:600;
  cursor:pointer;text-align:left}
.opt:hover:not(:disabled){border-color:var(--accent)}
.opt.correct{background:var(--ok-soft);border-color:var(--ok);color:var(--ok)}
.opt.wrong{background:var(--bad-soft);border-color:var(--bad);color:var(--bad)}
.opt:disabled{cursor:default}
.type-row{display:flex;gap:.5rem}
.type-in{flex:1;min-width:0;padding:.7rem .85rem;border-radius:.65rem;
  border:1.5px solid var(--border);background:var(--panel);color:var(--text);
  font-size:.95rem;font-weight:600;outline:none}
.type-in:focus{border-color:var(--accent)}
.dia{display:flex;gap:.3rem;flex-wrap:wrap;margin-top:.5rem}
.dia button{width:2.1rem;height:2.1rem;border-radius:.5rem;border:1px solid var(--border);
  background:var(--panel);color:var(--text);font-size:.9rem;font-weight:700;cursor:pointer}
.dia button:hover{border-color:var(--accent);color:var(--accent)}
.fb{margin-top:.7rem;padding:.65rem .85rem;border-radius:.65rem;font-size:.83rem;font-weight:700}
.fb.good{background:var(--ok-soft);color:var(--ok)}
.fb.mid{background:var(--warn-soft);color:var(--warn)}
.fb.bad{background:var(--bad-soft);color:var(--bad)}

.btn{border:1px solid var(--border);background:var(--panel);color:var(--text);
  padding:.65rem 1rem;border-radius:.7rem;font-size:.86rem;font-weight:700;cursor:pointer}
.btn:hover:not(:disabled){border-color:var(--accent);color:var(--accent)}
.btn.primary{background:var(--accent);border-color:var(--accent);color:#fff}
.btn.primary:hover:not(:disabled){background:var(--accent2);color:#fff}
.btn.ok{background:var(--ok-soft);border-color:var(--ok);color:var(--ok)}
.btn.danger{background:var(--bad-soft);border-color:var(--bad);color:var(--bad)}
.btn:disabled{opacity:.4;cursor:not-allowed}
.lesson-nav{display:flex;align-items:center;justify-content:space-between;gap:.6rem;
  margin-top:1.6rem;padding-top:1.2rem;border-top:1px solid var(--border);flex-wrap:wrap}
.lesson-nav .btn{flex:1;min-width:7rem}

.pending{background:var(--panel2);border:1px dashed var(--border);border-radius:.8rem;
  padding:1.5rem;text-align:center;color:var(--muted);font-size:.88rem;line-height:1.6}
.pending-focus{margin-top:.8rem;color:var(--text);font-weight:700;font-size:.9rem}

/* practice hub */
.practice-wrap{background:var(--panel);border:1px solid var(--border);
  border-radius:var(--r);padding:1.6rem 1.7rem;box-shadow:var(--shadow)}
.practice-wrap h2{margin:0 0 .3rem;font-size:1.4rem;letter-spacing:-.02em}
.practice-wrap .sub{margin:0 0 1.4rem;color:var(--muted);font-size:.88rem;font-weight:600}
.mode-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:.7rem;margin-bottom:1.4rem}
@media(max-width:700px){.mode-grid{grid-template-columns:1fr}}
.mode-card{background:var(--panel2);border:1.5px solid var(--border);border-radius:.9rem;
  padding:1rem;cursor:pointer;text-align:left;color:var(--text)}
.mode-card:hover{border-color:var(--accent)}
.mode-card.on{border-color:var(--accent);background:var(--soft)}
.mode-card .emoji{font-size:1.6rem;display:block;margin-bottom:.3rem}
.mode-card .name{font-weight:800;font-size:.95rem;display:block;margin-bottom:.2rem}
.mode-card .desc{font-size:.78rem;color:var(--muted);font-weight:600;line-height:1.4}
.scope-box{background:var(--panel2);border:1px solid var(--border);border-radius:.8rem;
  padding:1rem;margin-bottom:1.2rem}
.scope-box h3{margin:0 0 .7rem;font-size:.78rem;font-weight:900;text-transform:uppercase;
  letter-spacing:.08em;color:var(--muted)}
.scope-opt{display:flex;align-items:center;gap:.6rem;padding:.45rem 0;cursor:pointer;font-size:.9rem}
.scope-opt input{width:1.1rem;height:1.1rem;accent-color:var(--accent)}
.scope-opt .dim{color:var(--muted);font-size:.78rem;margin-left:auto;font-weight:600}

.session{background:var(--panel);border:1px solid var(--border);border-radius:var(--r);
  padding:1.6rem 1.7rem;box-shadow:var(--shadow)}
.session-top{display:flex;align-items:center;justify-content:space-between;
  gap:.7rem;margin-bottom:1rem;flex-wrap:wrap}
.session-score{font-size:.8rem;font-weight:800;color:var(--muted)}
.session-score b{color:var(--accent)}
.bar{height:.5rem;background:var(--border);border-radius:99px;overflow:hidden;margin-bottom:1.2rem}
.bar span{display:block;height:100%;background:linear-gradient(90deg,var(--accent),var(--accent2));
  border-radius:99px;transition:width .3s}
.session-q{font-size:clamp(1.2rem,3.4vw,1.7rem);font-weight:800;letter-spacing:-.02em;
  margin:0 0 1.1rem;line-height:1.25}
.session-q small{display:block;font-size:.72rem;font-weight:800;color:var(--muted);
  text-transform:uppercase;letter-spacing:.09em;margin-bottom:.35rem}
.session-audio{background:var(--soft);border:0;border-radius:.7rem;padding:.6rem 1rem;
  font-size:.85rem;font-weight:800;color:var(--accent);cursor:pointer;margin-bottom:.9rem}
.session-nav{display:flex;gap:.6rem;margin-top:1rem}

/* settings overlay */
.overlay{position:fixed;inset:0;background:rgba(8,10,15,.55);z-index:50;
  display:flex;align-items:flex-start;justify-content:center;padding:2rem 1rem;overflow-y:auto}
.panel{background:var(--panel);border:1px solid var(--border);border-radius:1rem;
  box-shadow:var(--shadow);width:100%;max-width:36rem;padding:1.4rem 1.5rem 1.6rem}
.panel-head{display:flex;align-items:center;justify-content:space-between;margin-bottom:1.1rem}
.panel-head h2{margin:0;font-size:1.2rem;letter-spacing:-.02em}
.sec{margin-bottom:1.5rem}
.sec h3{margin:0 0 .7rem;font-size:.78rem;font-weight:900;text-transform:uppercase;
  letter-spacing:.09em;color:var(--accent)}
.sec .help{font-size:.78rem;color:var(--muted);line-height:1.5;margin:.35rem 0 .7rem}
.row{display:flex;align-items:center;gap:.7rem;flex-wrap:wrap}
.row label{font-size:.85rem;font-weight:600}
input[type=range]{width:100%;accent-color:var(--accent)}
select{width:100%;padding:.6rem .7rem;border-radius:.6rem;border:1.5px solid var(--border);
  background:var(--panel2);color:var(--text);font-size:.85rem;font-weight:600}
textarea{width:100%;min-height:11rem;padding:.7rem;border-radius:.6rem;
  border:1.5px solid var(--border);background:var(--panel2);color:var(--text);
  font-family:ui-monospace,Menlo,Consolas,monospace;font-size:.72rem;line-height:1.5;
  resize:vertical}
.file-list{display:flex;flex-direction:column;gap:.4rem;margin-bottom:.7rem}
.file-row{display:flex;align-items:center;gap:.6rem;background:var(--panel2);
  border:1px solid var(--border);border-radius:.6rem;padding:.55rem .7rem;font-size:.8rem}
.file-row .name{font-weight:800;flex:1;min-width:0;overflow:hidden;text-overflow:ellipsis;
  white-space:nowrap}
.file-row .meta{color:var(--muted);font-size:.72rem;font-weight:600}
.file-row .mini{border:1px solid var(--border);background:transparent;color:var(--text);
  border-radius:.4rem;padding:.2rem .45rem;font-size:.7rem;font-weight:700;cursor:pointer}
.file-row .mini:hover{border-color:var(--accent);color:var(--accent)}
.file-row .mini.danger:hover{border-color:var(--bad);color:var(--bad)}
.fs-preview{background:var(--panel2);border:1px solid var(--border);border-radius:.6rem;
  padding:.8rem 1rem;margin-top:.5rem;font-size:1rem;line-height:1.5}
.toast{position:fixed;bottom:1.2rem;left:50%;transform:translateX(-50%);
  background:var(--text);color:var(--bg);padding:.7rem 1.1rem;border-radius:.7rem;
  font-size:.83rem;font-weight:700;z-index:100;box-shadow:var(--shadow);
  opacity:0;transition:opacity .25s;pointer-events:none}
.toast.on{opacity:1}

/* mobile lesson picker */
.mobile-lessons-btn{display:none}
@media(max-width:880px){
  .sidebar{display:none}
  .mobile-lessons-btn{display:block;width:100%;margin-bottom:1rem}
}
@media(max-width:560px){
  .lesson{padding:1.2rem 1rem 1.4rem}
  .practice-wrap,.session{padding:1.2rem 1rem}
  .topbar{padding:.9rem 0 .7rem}
  .brand h1{font-size:1rem}
  .brand p{display:none}
  .nav button{padding:.4rem .7rem;font-size:.75rem}
}

footer{margin-top:2rem;text-align:center;font-size:.72rem;color:var(--muted);line-height:1.7}
/* Settings Tabs */
.settings-tabs{display:flex;gap:.25rem;background:var(--panel2);border:1px solid var(--border);border-radius:.7rem;padding:.25rem;margin-bottom:1.2rem;overflow-x:auto}
.settings-tabs button{flex:1;border:0;background:transparent;color:var(--muted);padding:.6rem .4rem;border-radius:.5rem;font:inherit;font-size:.8rem;font-weight:700;cursor:pointer;white-space:nowrap;transition:.15s}
.settings-tabs button.active{background:var(--accent);color:#fff;box-shadow:0 2px 4px rgba(0,0,0,.1)}
.settings-tabs button:hover:not(.active){color:var(--text)}
.help-card{background:var(--panel2);border:1px solid var(--border);border-radius:.8rem;padding:1rem;margin-bottom:1rem}
.help-card h4{margin:0 0 .5rem;color:var(--accent);font-size:.95rem}
.help-card ol{margin:0;padding-left:1.2rem;font-size:.85rem;line-height:1.6;color:var(--text)}
.help-card li{margin-bottom:.4rem}
.help-card code{background:var(--bg);padding:2px 4px;border-radius:4px;font-size:.8rem}