:root{--navy:#0F2A4A;--navy2:#1B3D66;--blue:#1F5FD1;--amber:#F5B700;--bg:#F4F6FA;--line:#E2E8F0;--muted:#5B6B80;--ok:#166534;--okbg:#E7F8EE;--warn:#9A3412;--warnbg:#FFF1E8;--ybg:#FFF4CC;--ytx:#6B4A00}
*{box-sizing:border-box}
html,body{margin:0;height:100%}
body{font-family:'Be Vietnam Pro',system-ui,-apple-system,sans-serif;background:var(--bg);color:var(--navy);-webkit-text-size-adjust:100%}
button,input,textarea,select{font:inherit;color:inherit}
a{color:var(--blue)}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}
#toast{position:fixed;left:50%;bottom:calc(84px + env(safe-area-inset-bottom));transform:translateX(-50%);background:var(--navy);color:#fff;padding:10px 16px;border-radius:12px;font-size:14px;opacity:0;pointer-events:none;transition:opacity .2s;z-index:50;max-width:90vw;text-align:center}
#toast.show{opacity:1}

/* khung chính */
.shell{display:flex;min-height:100vh}
.side{display:none;width:230px;flex-shrink:0;background:var(--navy);color:#fff;padding:18px 12px;flex-direction:column;gap:4px;position:sticky;top:0;height:100vh}
.side .brand{font-weight:700;font-size:17px;padding:4px 10px 16px}
.side a{display:flex;align-items:center;gap:10px;padding:11px 12px;border-radius:10px;color:#DCE6F5;text-decoration:none;font-size:14px}
.side a.on{background:var(--navy2);color:#fff;font-weight:600}
.side .foot{margin-top:auto;font-size:12px;color:#9FB2CC;padding:8px 10px}
.main{flex:1;min-width:0;display:flex;flex-direction:column;padding-bottom:calc(68px + env(safe-area-inset-bottom))}
.tabs{position:fixed;left:0;right:0;bottom:0;background:#fff;border-top:1px solid var(--line);display:grid;grid-template-columns:repeat(5,1fr);padding:6px 4px calc(8px + env(safe-area-inset-bottom));z-index:20}
.tabs a{display:flex;flex-direction:column;align-items:center;gap:2px;font-size:11px;color:var(--muted);text-decoration:none;min-height:44px;justify-content:center;position:relative}
.tabs a.on{color:var(--blue);font-weight:600}
.tabs .dot,.side .dot{position:absolute;top:2px;right:calc(50% - 18px);min-width:18px;height:18px;border-radius:9px;background:#C2410C;color:#fff;font-size:11px;display:flex;align-items:center;justify-content:center;padding:0 5px;font-weight:700}
.side .dot{position:static;margin-left:auto}
@media(min-width:900px){.side{display:flex}.tabs{display:none}.main{padding-bottom:0}}

.top{background:var(--navy);color:#fff;padding:calc(12px + env(safe-area-inset-top)) 16px 14px;display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.top h1{margin:0;font-size:19px;flex:1;min-width:140px}
.pill{display:inline-flex;align-items:center;gap:6px;background:var(--navy2);border-radius:999px;padding:6px 11px;font-size:12px;font-weight:600;color:#fff;border:0;cursor:pointer;min-height:32px}
.led{width:8px;height:8px;border-radius:50%;background:#94A3B8;display:inline-block}
.led.on{background:#3DDC84}.led.off{background:#F87171}
.page{padding:14px;display:flex;flex-direction:column;gap:14px;max-width:1100px;width:100%}
@media(min-width:900px){.top{padding:16px 24px}.page{padding:20px 24px}}

.card{background:#fff;border-radius:16px;padding:16px}
.card h2{margin:0 0 10px;font-size:16px}
.muted{color:var(--muted)}
.small{font-size:12px}
.row{display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.grow{flex:1;min-width:0}
.btn{border:0;border-radius:12px;min-height:44px;padding:0 16px;font-size:14px;font-weight:700;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;gap:6px}
.btn-blue{background:var(--blue);color:#fff}
.btn-amber{background:var(--amber);color:var(--navy)}
.btn-ghost{background:#fff;border:1px solid #D5DCE6;font-weight:600}
.btn-warn{background:var(--warnbg);color:var(--warn);border:1px solid #FDBA8C;font-weight:600}
.btn-sm{min-height:36px;font-size:13px;padding:0 12px;border-radius:10px}
.btn:disabled{opacity:.5;cursor:default}
label.f{display:block;font-size:12px;font-weight:600;color:var(--muted);margin:12px 0 4px}
input.i,textarea.i,select.i{width:100%;border:1px solid #D5DCE6;border-radius:10px;padding:10px 12px;background:#fff;font-size:15px}
textarea.i{line-height:1.45;resize:vertical}
.hint{font-size:12px;color:var(--muted);line-height:1.45;margin:6px 0 0}
.seg{display:flex;flex-wrap:wrap;gap:6px}
.seg button{border:1px solid #D5DCE6;background:#fff;border-radius:999px;padding:7px 13px;font-size:13px;font-weight:600;cursor:pointer;min-height:36px}
.seg button.on{background:var(--navy);border-color:var(--navy);color:#fff}
.sw{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:10px 0;border-bottom:1px solid var(--line)}
.sw:last-child{border-bottom:0}
.sw .t b{display:block;font-size:14px}
.sw .t span{font-size:12px;color:var(--muted)}
.toggle{width:50px;height:30px;border-radius:15px;border:0;background:#C5CEDA;position:relative;cursor:pointer;flex-shrink:0}
.toggle::after{content:'';position:absolute;top:3px;left:3px;width:24px;height:24px;border-radius:50%;background:#fff;transition:left .15s}
.toggle.on{background:var(--blue)}.toggle.on::after{left:23px}

.stats{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:8px}
.stat{background:#fff;border-radius:12px;padding:10px 6px;text-align:center}
.stat b{display:block;font-size:20px}
.stat span{font-size:11px;color:var(--muted)}
.stat.y{background:var(--ybg)}.stat.y b{color:#8A5A00}
.stat.o b{color:#C2410C}

/* danh sách chat */
.list{background:#fff;border-radius:16px;overflow:hidden}
.ci{display:flex;gap:12px;align-items:flex-start;padding:12px 14px;border-bottom:1px solid #EEF2F7;text-decoration:none;color:inherit}
.ci:last-child{border-bottom:0}
.ci:hover{background:#F8FAFC}
.av{width:42px;height:42px;border-radius:50%;background:#DCE6F5;display:flex;align-items:center;justify-content:center;font-weight:700;font-size:14px;flex-shrink:0;position:relative}
.av .ch{position:absolute;right:-2px;bottom:-2px;width:18px;height:18px;border-radius:6px;font-size:10px;font-weight:700;color:#fff;display:flex;align-items:center;justify-content:center;border:2px solid #fff}
.ch.zalo{background:#0068FF}.ch.messenger{background:#7B3FE4}
.ci .b{flex:1;min-width:0;display:flex;flex-direction:column;gap:3px}
.ci .l1{display:flex;justify-content:space-between;gap:8px}
.ci .nm{font-weight:600;font-size:14px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.ci .tm{font-size:11px;color:var(--muted);flex-shrink:0}
.ci .lt{font-size:13px;color:var(--muted);overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.tags{display:flex;gap:4px;flex-wrap:wrap}
.tag{font-size:10px;font-weight:700;border-radius:6px;padding:2px 7px}
.t-y{background:var(--ybg);color:var(--ytx)}.t-o{background:var(--warnbg);color:var(--warn)}.t-g{background:var(--okbg);color:var(--ok)}.t-n{background:#EEF2F7;color:#475569}.t-b{background:#E5F0FF;color:#0B4BB3}.t-r{background:#FEE2E2;color:#991B1B}
.empty{padding:28px 16px;text-align:center;color:var(--muted);font-size:14px}

/* màn chat */
.chat{display:flex;flex-direction:column;height:calc(100vh - 68px - env(safe-area-inset-bottom))}
@media(min-width:900px){.chat{height:100vh}}
.chat .hd{background:#fff;border-bottom:1px solid var(--line);padding:calc(8px + env(safe-area-inset-top)) 10px 8px 4px;display:flex;align-items:center;gap:8px}
.back{width:44px;height:44px;display:flex;align-items:center;justify-content:center;border:0;background:none;cursor:pointer;text-decoration:none;color:var(--navy)}
.chat .hd .nm{font-weight:700;font-size:16px}
.chat .hd .sub{font-size:12px;color:var(--muted)}
.msgs{flex:1;overflow-y:auto;padding:14px;display:flex;flex-direction:column;gap:8px;background:#F8FAFC}
.m{display:flex;flex-direction:column;gap:2px;max-width:82%}
.m.kh{align-self:flex-start;align-items:flex-start}
.m.out{align-self:flex-end;align-items:flex-end}
.m .bb{padding:9px 13px;font-size:15px;line-height:1.45;white-space:pre-wrap;word-break:break-word}
.m.kh .bb{background:#fff;border:1px solid var(--line);border-radius:16px 16px 16px 4px}
.m.out .bb{background:#DCE8FF;border-radius:16px 16px 4px 16px}
.m.out.staff .bb{background:#E3F4EC}
.m .mt{font-size:11px;color:var(--muted)}
.m.failed .mt{color:#B91C1C;font-weight:600}
.day{align-self:center;font-size:11px;color:var(--muted);margin:6px 0}
.banner{margin:10px 12px 0;border-radius:12px;padding:10px 12px;font-size:13px;line-height:1.45;display:flex;flex-direction:column;gap:8px}
.banner.o{background:var(--warnbg);color:#7C2D12}
.banner.r{background:#FEE2E2;color:#7F1D1D}
.banner.b{background:#E5F0FF;color:#0B3A8C}
.dock{background:#fff;border-top:1px solid var(--line);padding:10px 12px calc(10px + env(safe-area-inset-bottom) * 0);display:flex;flex-direction:column;gap:8px}
.draft{border:2px solid var(--amber);border-radius:14px;padding:10px;display:flex;flex-direction:column;gap:8px}
.draft .why{font-size:12px;color:#334155;background:#F1F5F9;border-radius:8px;padding:6px 8px}
.order{border:2px solid var(--amber);border-radius:14px;padding:12px;margin:10px 12px 0;background:#fff;display:flex;flex-direction:column;gap:6px}
.order.done{border-color:#86D1A6}
.kv{display:flex;justify-content:space-between;gap:10px;font-size:13px}
.kv span:first-child{color:var(--muted)}
.kv span:last-child{font-weight:600;text-align:right}
.composer{display:flex;gap:8px;align-items:flex-end}
.composer textarea{flex:1;min-height:44px;max-height:140px}

/* đăng nhập */
.login{min-height:100vh;display:flex;align-items:center;justify-content:center;padding:20px;background:var(--navy)}
.login .card{width:100%;max-width:380px;padding:24px}
.login h1{margin:0 0 4px;font-size:22px}

table.t{width:100%;border-collapse:collapse;font-size:13px}
table.t th,table.t td{padding:8px 6px;border-bottom:1px solid var(--line);text-align:left;vertical-align:top}
table.t th{font-size:12px;color:var(--muted);font-weight:600}
.lesson{display:flex;gap:8px;align-items:flex-start;padding:8px 0;border-bottom:1px solid var(--line);font-size:13px;line-height:1.45}
.lesson:last-child{border-bottom:0}
.code{font-family:ui-monospace,Menlo,Consolas,monospace;font-size:18px;font-weight:700;letter-spacing:1px;background:#F1F5F9;border-radius:10px;padding:10px 12px;display:inline-block;user-select:all}
.typing{display:inline-flex;gap:4px;padding:12px 14px;background:#fff;border:1px solid var(--line);border-radius:16px;align-self:flex-start}
.typing i{width:7px;height:7px;border-radius:50%;background:#94A3B8;animation:bl 1.2s infinite}
.typing i:nth-child(2){animation-delay:.2s}.typing i:nth-child(3){animation-delay:.4s}
@keyframes bl{0%,60%,100%{opacity:.3}30%{opacity:1}}
.chips{display:flex;gap:6px;overflow-x:auto;padding-bottom:2px}
.chip{flex-shrink:0;border:1px solid #C9D6EA;background:#F5F8FD;border-radius:999px;padding:7px 12px;font-size:13px;cursor:pointer;min-height:36px}
.grid2{display:grid;grid-template-columns:repeat(auto-fit,minmax(300px,1fr));gap:14px}

.autobtn{display:inline-flex;align-items:center;gap:8px;background:var(--navy2);color:#fff;border:0;border-radius:999px;padding:5px 8px 5px 14px;font-size:13px;font-weight:600;cursor:pointer;min-height:40px}
.autobtn b{font-size:12px;min-width:30px;text-align:left}
.autobtn.on{background:var(--amber);color:var(--navy)}
.autobtn.locked{opacity:.75}
.autobtn .mini{width:38px;height:22px;border-radius:11px;background:#5B6B80;position:relative;flex-shrink:0}
.autobtn .mini::after{content:'';position:absolute;top:3px;left:3px;width:16px;height:16px;border-radius:50%;background:#fff;transition:left .15s}
.autobtn .mini.on{background:var(--navy)}.autobtn .mini.on::after{left:19px}
.updbar{display:block;width:100%;border:0;background:#16A34A;color:#fff;font:inherit;font-size:14px;font-weight:700;padding:calc(10px + env(safe-area-inset-top)) 14px 10px;cursor:pointer;text-align:center}
@media(max-width:480px){.top .pill{font-size:11px;padding:5px 9px}.autobtn{font-size:12px;padding-left:10px}}