:root{--bg:#f6f6f7;--card:#fff;--ink:#111827;--muted:#6b7280;--brand:#0f766e;--brand-2:#115e59;--brand-soft:#ccfbf1;--warn:#b45309;--warn-bg:#fef3c7;--err:#b91c1c;--line:#e5e7eb;--bubble-ai:#fff;--bubble-me:#0f766e;--radius:14px;--safe-b:env(safe-area-inset-bottom,0px)}
*{box-sizing:border-box}html{-webkit-text-size-adjust:100%}
body{margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans TC","PingFang TC","Microsoft JhengHei",sans-serif;background:var(--bg);color:var(--ink);font-size:16px;line-height:1.55;min-height:100dvh}
button{font:inherit;cursor:pointer}input,textarea,select{font:inherit}
.hidden{display:none!important}
.app{max-width:720px;margin:0 auto;min-height:100dvh;display:flex;flex-direction:column}
.topbar{position:sticky;top:0;z-index:5;background:#fff;color:var(--ink);padding:10px 14px;display:flex;align-items:center;gap:10px;min-height:54px;border-bottom:1px solid var(--line)}
.topbar h1{font-size:18px;margin:0;flex:1;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;font-weight:600}
.topbar button{background:#f1f3f5;color:var(--ink);border:0;border-radius:12px;padding:8px 12px;min-height:40px;font-weight:500}
.topbar button.primary{background:var(--brand);color:#fff;font-weight:600}
.disclaimer{background:var(--warn-bg);color:var(--warn);font-size:13px;padding:7px 14px;text-align:center;border-bottom:1px solid #fde68a}
main{flex:1;display:flex;flex-direction:column}
.screen{padding:16px 14px calc(24px + var(--safe-b));flex:1}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:16px;margin-bottom:14px}
.card h2{font-size:18px;margin:0 0 8px}
.card p.muted{margin:0 0 10px}
.muted{color:var(--muted);font-size:14px}
.field{margin-bottom:12px}.field label{display:block;font-size:14px;color:var(--muted);margin-bottom:4px}
.field input,.field textarea,.field select{width:100%;padding:12px;border:1px solid #cbd5e1;border-radius:10px;font-size:16px;background:#fff}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;border:0;border-radius:12px;padding:12px 16px;min-height:46px;font-size:16px;background:var(--brand);color:#fff;font-weight:600}
.btn.block{width:100%}.btn.secondary{background:#e2e8f0;color:var(--ink);font-weight:500}.btn.ghost{background:transparent;color:var(--brand)}
.btn:disabled{opacity:.5;cursor:default}
.error{color:var(--err);font-size:14px;margin:6px 0}
.login-wrap{display:flex;align-items:center;justify-content:center;min-height:calc(100dvh - 90px)}
.login-wrap .card{width:100%;max-width:380px}
.brand{text-align:center;margin-bottom:12px}.brand .logo{width:56px;height:56px;border-radius:16px;margin:0 auto 8px;display:block}
.brand h2{margin:0;font-size:20px}
.unit{display:block;width:100%;text-align:left;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:16px;margin-bottom:12px;color:var(--ink)}
.unit .t{font-size:18px;font-weight:600}.unit .d{color:var(--muted);font-size:14px;margin-top:4px}
.tasks{display:grid;gap:10px}
.task{display:flex;align-items:center;gap:12px;width:100%;text-align:left;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:14px;min-height:64px;color:var(--ink)}
.task .no{width:40px;height:40px;border-radius:12px;background:var(--brand-soft);color:var(--brand-2);display:flex;align-items:center;justify-content:center;font-weight:700;flex-shrink:0}
.task .name{font-size:17px;font-weight:600;flex:1}
.task .state{font-size:12px;padding:3px 8px;border-radius:999px;background:#e2e8f0;color:var(--muted)}
.task .state.active{background:#dbeafe;color:#1d4ed8}.task .state.completed{background:#dcfce7;color:#15803d}
.chat{flex:1;display:flex;flex-direction:column;min-height:0}
.msgs{flex:1;overflow-y:auto;padding:14px 12px 8px;display:flex;flex-direction:column;gap:12px;-webkit-overflow-scrolling:touch}
.msg{max-width:88%;padding:11px 14px;border-radius:16px;white-space:pre-wrap;word-break:break-word;font-size:16px;line-height:1.6}
.msg.ai{align-self:flex-start;background:var(--bubble-ai);border:1px solid var(--line);border-bottom-left-radius:6px}
.msg.me{align-self:flex-end;background:var(--bubble-me);color:#fff;border-bottom-right-radius:6px}
.msg.sys{align-self:center;background:transparent;color:var(--muted);font-size:13px;padding:4px 10px;text-align:center}
.msg.ai b,.msg.ai strong{font-weight:700}
.cite{display:inline-block;font-size:12px;line-height:18px;padding:0 6px;margin:0 1px;border-radius:999px;background:var(--brand-soft);color:var(--brand-2);border:0;vertical-align:1px;cursor:pointer}
.sources{margin-top:8px;padding-top:8px;border-top:1px dashed var(--line);font-size:13px;color:var(--muted)}
.sources .src{margin-top:4px}
.sources .src .q{display:block;color:var(--ink);background:#f8fafc;border-left:3px solid var(--brand);padding:6px 8px;border-radius:6px;margin-top:2px;white-space:pre-wrap;max-height:120px;overflow:auto}
.typing::after{content:"▍";animation:blink 1s steps(1) infinite;color:var(--brand)}
@keyframes blink{50%{opacity:0}}
.composer{position:sticky;bottom:0;background:var(--bg);padding:8px 10px calc(8px + var(--safe-b));border-top:1px solid var(--line);display:flex;gap:8px;align-items:flex-end}
.composer textarea{flex:1;resize:none;max-height:140px;min-height:46px;padding:12px;border:1px solid #cbd5e1;border-radius:14px;font-size:16px;background:#fff}
.composer button{min-width:60px;min-height:46px;border-radius:14px;border:0;background:var(--brand);color:#fff;font-weight:600}
.composer button:disabled{opacity:.5}
.quick{display:flex;gap:8px;overflow-x:auto;padding:6px 10px 0;scrollbar-width:none}.quick::-webkit-scrollbar{display:none}
.quick button{flex-shrink:0;border:1px solid var(--line);background:#fff;border-radius:999px;padding:7px 12px;font-size:14px;color:var(--brand-2)}
.modal{position:fixed;inset:0;background:rgba(0,0,0,.45);display:flex;align-items:flex-end;justify-content:center;z-index:20}
.modal .sheet{background:#fff;width:100%;max-width:720px;max-height:88dvh;border-radius:18px 18px 0 0;padding:16px 16px calc(16px + var(--safe-b));overflow:auto}
.sheet h3{margin:0 0 10px;font-size:18px}
.summary{white-space:pre-wrap;background:#f8fafc;border:1px solid var(--line);border-radius:10px;padding:12px;font-size:15px;line-height:1.6}
.row{display:flex;gap:8px;margin-top:12px}.row .btn{flex:1}
.toast{position:fixed;left:50%;bottom:calc(90px + var(--safe-b));transform:translateX(-50%);background:#111827;color:#fff;padding:10px 16px;border-radius:999px;font-size:14px;z-index:30;opacity:0;transition:opacity .2s;pointer-events:none}
.toast.show{opacity:1}
.history li{padding:8px 0;border-bottom:1px solid var(--line);font-size:14px;display:flex;justify-content:space-between;gap:8px}
.history li a{color:var(--brand);text-decoration:none}
.install-tip{font-size:13px;color:var(--muted);text-align:center;margin-top:16px}
@media (min-width:720px){.msg{max-width:78%}}

/* ---- 教材單元卡（lesson card）---- */
.hello{font-size:16px;color:var(--muted);margin:2px 0 12px}
.lesson{display:block;width:100%;text-align:left;background:#fff;border:1px solid var(--line);border-radius:22px;padding:18px 18px 14px;margin-bottom:16px;color:var(--ink);box-shadow:0 1px 2px rgba(0,0,0,.03)}
.lesson-btn{cursor:pointer}
.lesson-head{display:flex;align-items:flex-start;justify-content:space-between;gap:10px;margin-bottom:12px}
.eyebrow{font-size:15px;color:var(--muted);margin-bottom:4px}
.lesson-title{font-size:26px;line-height:1.3;font-weight:800;margin:0;letter-spacing:-.01em}
.pill{flex-shrink:0;font-size:14px;color:#374151;background:#eef0f2;border-radius:999px;padding:5px 11px;margin-top:4px;white-space:nowrap}
.cover{display:block;width:100%;aspect-ratio:16/10;object-fit:cover;border-radius:16px;margin:4px 0 10px;background:#eef2f1}
.cover-sm{aspect-ratio:16/7}
.cover-ph{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:8px;background:linear-gradient(135deg,#e6f4f1,#f3f7f6);color:var(--brand-2);font-weight:700;font-size:18px}
.caption{font-size:15px;line-height:1.6;color:#4b5563;margin:0 0 10px}
.progress-line{display:flex;justify-content:space-between;font-size:14px;color:var(--muted);border-top:1px solid var(--line);padding-top:10px;margin-top:4px}
.h-flow{font-size:21px;font-weight:800;margin:14px 0 8px}
.flow{list-style:none;margin:0;padding:0}
.flow li{margin:0 0 10px}
.step{display:flex;align-items:flex-start;gap:8px;width:100%;text-align:left;background:#fff;border:1px solid var(--line);border-radius:16px;padding:14px 12px;color:var(--ink);min-height:64px}
.step:active{background:#f8fafc}
.step-no{font-size:20px;font-weight:800;line-height:1.35;min-width:28px}
.step-body{flex:1;display:flex;flex-direction:column;gap:3px}
.step-title{font-size:19px;font-weight:700;line-height:1.35}
.step-min{font-size:13px;font-weight:500;color:var(--muted);margin-left:8px;white-space:nowrap}
.step-obj{font-size:14px;color:#4b5563;line-height:1.5}
.state{font-size:12px;padding:4px 9px;border-radius:999px;background:#e2e8f0;color:var(--muted);white-space:nowrap;margin-top:4px}
.state.active{background:#dbeafe;color:#1d4ed8}.state.completed{background:#dcfce7;color:#15803d}.state.go{background:var(--brand-soft);color:var(--brand-2)}
.history{list-style:none;padding:0;margin:0}