:root{
  --bg:#f7f5f0;--card:#fff;--fg:#1d1f23;--mut:#666b73;--line:#e3e0d8;
  --acc:#1f4fa8;--acc-fg:#fff;--me:#e4ecfb;--tl:#1f4fa8;--tlbg:#eef3fd;
  --ok:#1d7a3a;--bad:#b3261e;--warn:#b26a00;--code:#f0ede6
}
@media (prefers-color-scheme:dark){:root{
  --bg:#15171b;--card:#1f2228;--fg:#e9e7e2;--mut:#9aa0a8;--line:#30343b;
  --acc:#7ea6ff;--acc-fg:#0d1320;--me:#26324a;--tl:#a9c2ff;--tlbg:#232c3d;
  --ok:#5cc17e;--bad:#ff7a70;--warn:#e0a54a;--code:#2a2e35
}}
*{box-sizing:border-box}
html,body{height:100%}
body{margin:0;background:var(--bg);color:var(--fg);font:16px/1.5 system-ui,-apple-system,"Segoe UI",sans-serif;height:100dvh;overflow:hidden}
[hidden]{display:none !important}
button,input,select,textarea{font:inherit;color:inherit}
button{border:1px solid var(--line);background:var(--card);border-radius:10px;padding:8px 12px;cursor:pointer;min-height:40px}
button:disabled{opacity:.45;cursor:default}
button.primary{background:var(--acc);border-color:var(--acc);color:var(--acc-fg)}
button.big{padding:12px 22px;font-size:1.05rem}
.mut{color:var(--mut)}.small{font-size:.85rem}.err{color:var(--bad)}
code{background:var(--code);padding:1px 5px;border-radius:4px;font-size:.9em}
h1{font-size:1.5rem;margin:.2em 0 .4em}
.card h2{font-size:1.05rem;margin:0 0 10px}.card h3{font-size:.95rem;margin:12px 0 4px}
a{color:var(--acc)}

/* screens before sign-in */
.screen:not(#main){height:100dvh;overflow-y:auto;padding:24px 16px}
.screen:not(#main) .card{max-width:480px;margin:0 auto}
.intro{text-align:center}
.intro form{text-align:left;margin-top:16px}
.intro .big{width:100%}
.intro #haveAccount{width:100%}
.logo{width:72px;height:72px}
.or{text-align:center;margin:12px 0}
.code{font:600 1.25rem/1.4 ui-monospace,SFMono-Regular,Menlo,monospace;letter-spacing:.04em;background:var(--code);
  padding:10px 12px;border-radius:10px;text-align:center;overflow-wrap:anywhere;margin:10px 0;display:block}
fieldset{border:1px solid var(--line);border-radius:10px;margin:0 0 12px;padding:10px 12px}
legend{padding:0 4px;color:var(--mut);font-size:.9rem}
.seg{display:flex;gap:16px;flex-wrap:wrap;margin-bottom:10px}
.seg label{display:flex;gap:6px;align-items:center;margin:0}

label{display:block;margin:0 0 12px}
label>span:first-child{display:block}
label input:not([type=checkbox]):not([type=radio]),label select{display:block;width:100%;margin-top:4px;padding:8px 10px;border-radius:10px;border:1px solid var(--line);background:var(--bg)}
label.check{display:flex;gap:8px;align-items:flex-start}
label.check>span:first-child{display:inline}
label.check input{margin-top:5px}
.row{display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.row input{flex:1;min-width:0;padding:8px 10px;border-radius:10px;border:1px solid var(--line);background:var(--bg)}

/* main screen */
#main{display:flex;flex-direction:column;height:100dvh}
header{display:flex;align-items:center;justify-content:space-between;gap:8px;
  padding:calc(env(safe-area-inset-top) + 8px) 16px 8px;border-bottom:1px solid var(--line)}
.brand{font-weight:700;font-size:1.05rem;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.brand select{font-weight:700;border:0;background:transparent;padding:4px 0;max-width:46vw}
.chip.end{margin-left:auto}
header button{white-space:nowrap}
.modes{display:flex;border:1px solid var(--line);border-radius:999px;overflow:hidden;flex:none}
.modes button{border:0;border-radius:0;min-height:34px;padding:4px 12px;background:transparent;font-size:.9rem}
.modes button.on{background:var(--acc);color:var(--acc-fg)}
@media (max-width:430px){.modes button{padding:4px 8px;font-size:.8rem}.brand{font-size:.95rem}}

.tabs{display:flex;gap:4px;padding:6px 16px;border-bottom:1px solid var(--line);overflow-x:auto}
.tabs button{border:0;background:transparent;min-height:34px;padding:4px 10px;border-radius:8px;color:var(--mut);white-space:nowrap}
.tabs button.on{color:var(--fg);background:var(--card);box-shadow:0 0 0 1px var(--line)}
.badge{display:inline-block;min-width:1.4em;padding:0 5px;border-radius:999px;background:var(--acc);color:var(--acc-fg);font-size:.75rem;line-height:1.4em;text-align:center}

.pane{flex:1;overflow-y:auto;padding:16px;max-width:760px;width:100%;margin:0 auto}
#lesson{display:flex;flex-direction:column;padding:0}
.card{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:16px;margin:0 0 16px}

/* chat */
.chat{flex:1;overflow-y:auto;padding:16px;display:flex;flex-direction:column;gap:10px}
.msg{max-width:88%;padding:10px 14px;border-radius:14px;overflow-wrap:anywhere}
.msg p{margin:.3em 0}.msg p:first-child{margin-top:0}.msg p:last-child{margin-bottom:0}
.msg ul,.msg ol{margin:.3em 0;padding-left:1.3em}
.msg table{border-collapse:collapse;display:block;overflow-x:auto}
.msg th,.msg td{border:1px solid var(--line);padding:3px 8px}
.msg.teacher{align-self:flex-start;background:var(--card);border:1px solid var(--line);border-bottom-left-radius:4px}
.msg.learner{align-self:flex-end;background:var(--me);border-bottom-right-radius:4px}
.msg.learner .spoken{font-size:.75rem;color:var(--mut);display:block}
.msg.sys{align-self:center;background:transparent;color:var(--mut);font-size:.9rem;text-align:center}
.msg .say{margin-top:6px;border:0;background:transparent;padding:2px 6px;min-height:0;color:var(--mut);font-size:.85rem}
.tl{color:var(--tl);background:var(--tlbg);border-radius:5px;padding:0 3px;cursor:pointer;font-weight:500}
.typing::after{content:"▍";animation:blink 1s steps(1) infinite}
@keyframes blink{50%{opacity:0}}
.startbox{padding:24px 16px;text-align:center}
.evaluation{align-self:stretch}
.evaluation ul{margin:4px 0;padding-left:1.3em}
.evaluation details{margin-top:10px}
.facts{display:grid;grid-template-columns:auto 1fr;gap:4px 12px;margin:0}
.facts dt{color:var(--mut)}.facts dd{margin:0}

.composer{border-top:1px solid var(--line);padding:8px 12px calc(env(safe-area-inset-bottom) + 8px);background:var(--bg)}
.tools{display:flex;align-items:center;gap:8px;margin-bottom:6px;min-height:30px}
.chip{min-height:30px;padding:2px 10px;font-size:.85rem;border-radius:999px}
.inputrow{display:flex;gap:8px;align-items:flex-end}
.inputrow textarea{flex:1;min-height:44px;max-height:30vh;resize:none;padding:10px 12px;border-radius:12px;border:1px solid var(--line);background:var(--card)}
.inputrow button{min-width:44px;min-height:44px}
.mic{font-size:1.15rem}
.mic.rec{background:var(--bad);border-color:var(--bad);color:#fff;animation:pulse 1.2s infinite}
.mic.busy{opacity:.6}
@keyframes pulse{50%{box-shadow:0 0 0 6px color-mix(in srgb,var(--bad) 25%,transparent)}}
body.voice .inputrow .mic{flex:1;min-height:56px;font-size:1.4rem}
body.voice .inputrow textarea{flex:0 1 40%}

/* vocabulary */
.vq{font-size:1.5rem;font-weight:600;margin:8px 0 4px}
.vsub{color:var(--mut);margin-bottom:12px}
.vans{font-size:1.2rem;margin:12px 0}
.vok{color:var(--ok)}.vbad{color:var(--bad)}
.progress{height:6px;background:var(--line);border-radius:3px;overflow:hidden;margin-bottom:12px}
.progress>div{height:100%;background:var(--acc)}

/* more */
.devices{list-style:none;margin:0 0 10px;padding:0}
.devices li{display:flex;justify-content:space-between;align-items:center;gap:8px;padding:6px 0;border-bottom:1px solid var(--line)}