:root{
  --bg:#f7f8fc;--surface:#fff;--surface-2:#f9fafb;--text:#101828;--muted:#667085;--border:#e4e7ec;
  --primary:#6c5ce7;--primary-dark:#5848d8;--teal:#16b8a6;--green:#12b76a;--warning:#f79009;--danger:#f04438;
  --sidebar:268px;--shadow:0 14px 38px rgba(16,24,40,.08);--shadow-sm:0 7px 20px rgba(16,24,40,.06);
}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif;background:var(--bg);color:var(--text);-webkit-font-smoothing:antialiased}
body.dark{--bg:#0b1120;--surface:#111827;--surface-2:#182132;--text:#f9fafb;--muted:#98a2b3;--border:#263449;--shadow:0 14px 38px rgba(0,0,0,.28);--shadow-sm:0 7px 20px rgba(0,0,0,.22)}
a{text-decoration:none;color:inherit}button,input,select,textarea{font:inherit}.container{width:min(1180px,calc(100% - 40px));margin:auto}.hidden{display:none!important}
.muted{color:var(--muted)}.danger{color:var(--danger)}.success{color:var(--green)}
.btn{border:0;border-radius:13px;padding:11px 17px;font-weight:760;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;gap:8px;transition:.18s;white-space:nowrap}
.btn:hover{transform:translateY(-1px)}.btn:disabled{opacity:.55;cursor:not-allowed;transform:none}
.btn-primary{background:linear-gradient(135deg,var(--primary),#8b76f3);color:#fff;box-shadow:0 8px 18px rgba(108,92,231,.22)}
.btn-teal{background:var(--teal);color:#fff}.btn-secondary{background:var(--surface);color:var(--text);border:1px solid var(--border)}.btn-danger{background:#fff1f0;color:#b42318;border:1px solid #fecdca}.dark .btn-danger{background:#301b1c;color:#fda29b;border-color:#5b292a}
.icon-btn{width:42px;height:42px;border-radius:12px;border:1px solid var(--border);background:var(--surface);color:var(--text);cursor:pointer;display:grid;place-items:center}
.pill{display:inline-flex;align-items:center;padding:6px 10px;border-radius:999px;background:#f1efff;color:#5948d8;font-size:12px;font-weight:820}.pill.teal{background:#e9fbf8;color:#0e8174}.pill.green{background:#ecfdf3;color:#027a48}.pill.orange{background:#fff7e8;color:#b54708}
.card{background:var(--surface);border:1px solid var(--border);border-radius:20px;padding:22px;box-shadow:var(--shadow-sm)}
.input,.select,.textarea{width:100%;border:1px solid var(--border);background:var(--surface);color:var(--text);border-radius:12px;padding:12px 13px;outline:none}.input:focus,.select:focus,.textarea:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(108,92,231,.11)}
.form-row{margin-top:15px}.form-row label{display:block;font-size:13px;font-weight:760;margin-bottom:7px}.check{display:flex;align-items:center;gap:8px;color:var(--muted);font-size:14px}.inline{display:flex;align-items:center;justify-content:space-between;gap:12px}.stack{display:flex;flex-direction:column;gap:12px}
.topnav{height:76px;background:rgba(255,255,255,.9);backdrop-filter:blur(16px);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:30}.dark .topnav{background:rgba(17,24,39,.9)}
.topnav .container{height:100%;display:flex;align-items:center;justify-content:space-between}.brand img{width:170px;display:block}.navlinks{display:flex;gap:24px;align-items:center;color:var(--muted);font-weight:670}.navlinks a:hover{color:var(--text)}
.hero{padding:76px 0 66px}.hero-grid{display:grid;grid-template-columns:1.04fr .96fr;gap:58px;align-items:center}.hero h1{font-size:clamp(42px,6vw,74px);line-height:1.02;letter-spacing:-3px;margin:17px 0}.hero p{font-size:18px;line-height:1.7;color:var(--muted);max-width:650px}.grad{background:linear-gradient(135deg,var(--primary),var(--teal));-webkit-background-clip:text;color:transparent}.hero-actions{display:flex;gap:11px;flex-wrap:wrap;margin-top:26px}.hero-art img{width:100%;filter:drop-shadow(0 18px 30px rgba(76,62,178,.10))}
.section{padding:66px 0}.section-title{font-size:35px;letter-spacing:-1.2px;margin:0 0 10px}.section-sub{margin:0 0 30px;color:var(--muted);line-height:1.7}
.grid-2{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.grid-3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}.grid-4{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:15px}
.course-card{padding:0;overflow:hidden}.course-card img{width:100%;height:220px;object-fit:cover;display:block}.course-card .body{padding:22px}.course-card h3{margin:12px 0 8px}.course-card p{line-height:1.6}
.feature-icon{width:46px;height:46px;border-radius:13px;display:grid;place-items:center;background:#f2f0ff;font-size:20px;margin-bottom:14px}.dark .feature-icon{background:#211d3e}
.footer{border-top:1px solid var(--border);padding:27px 0;color:var(--muted);margin-top:38px}
.auth-wrap{min-height:100vh;display:grid;grid-template-columns:.94fr 1.06fr}.auth-side{padding:58px;display:flex;align-items:center;justify-content:center;background:linear-gradient(145deg,#101828,#1d2939);color:#fff;position:relative;overflow:hidden}.auth-side:after{content:"";position:absolute;width:390px;height:390px;border-radius:50%;background:linear-gradient(135deg,var(--primary),var(--teal));filter:blur(95px);opacity:.3;right:-80px;bottom:-100px}.auth-copy{max-width:520px;position:relative;z-index:1}.auth-copy img{width:190px;filter:brightness(0) invert(1)}.auth-copy h1{font-size:47px;line-height:1.05;letter-spacing:-2px;margin:32px 0 16px}.auth-copy p{color:#d0d5dd;line-height:1.75;font-size:17px}.auth-main{display:flex;align-items:center;justify-content:center;padding:34px}.auth-card{width:min(470px,100%);background:var(--surface);border:1px solid var(--border);border-radius:24px;padding:30px;box-shadow:var(--shadow)}.auth-card h2{font-size:29px;margin:0 0 7px}.auth-footer{text-align:center;color:var(--muted);font-size:14px;margin-top:18px}
.app{min-height:100vh}.sidebar{position:fixed;inset:0 auto 0 0;width:var(--sidebar);background:var(--surface);border-right:1px solid var(--border);padding:20px 15px;z-index:40}.sidebar .brand{padding:1px 10px 20px}.side-label{font-size:10px;text-transform:uppercase;letter-spacing:1.45px;color:var(--muted);font-weight:850;padding:0 13px 7px}.side-nav{display:flex;flex-direction:column;gap:5px}.side-link{padding:11px 13px;border-radius:12px;color:var(--muted);font-weight:690;display:flex;gap:11px;align-items:center}.side-link:hover,.side-link.active{background:var(--surface-2);color:var(--text)}.side-link.active{box-shadow:inset 3px 0 0 var(--primary)}
.sidebar-bottom{position:absolute;left:15px;right:15px;bottom:17px}.student-mini{display:flex;align-items:center;gap:10px;padding:10px;border:1px solid var(--border);border-radius:13px;background:var(--surface-2)}.avatar{width:40px;height:40px;border-radius:50%;display:grid;place-items:center;background:linear-gradient(135deg,var(--primary),var(--teal));color:#fff;font-weight:850;flex:0 0 auto}
.main{margin-left:var(--sidebar);min-height:100vh}.appbar{height:72px;border-bottom:1px solid var(--border);background:var(--surface);display:flex;align-items:center;justify-content:space-between;padding:0 27px;position:sticky;top:0;z-index:25}.appbar h3{margin:0;font-size:18px}.appbar-actions{display:flex;align-items:center;gap:9px}.content{padding:27px}
.welcome{display:flex;align-items:center;justify-content:space-between;gap:22px;padding:28px;border-radius:23px;background:linear-gradient(135deg,#101828,#312e81);color:#fff;overflow:hidden;position:relative}.welcome:after{content:"";position:absolute;width:230px;height:230px;border-radius:50%;background:#16b8a6;filter:blur(44px);opacity:.20;right:-45px;top:-90px}.welcome h1{margin:0 0 7px;font-size:32px;letter-spacing:-.7px}.welcome p{margin:0;color:#d0d5dd}.welcome .btn{position:relative;z-index:2}
.stats{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px;margin:20px 0}.stat{background:var(--surface);border:1px solid var(--border);border-radius:17px;padding:18px;box-shadow:var(--shadow-sm)}.stat b{font-size:25px;display:block;margin:6px 0}.progress{height:8px;background:#eaecf0;border-radius:999px;overflow:hidden}.dark .progress{background:#344054}.progress span{display:block;height:100%;background:linear-gradient(90deg,var(--primary),var(--teal));border-radius:999px}
.lesson-list{display:flex;flex-direction:column}.lesson{display:flex;align-items:center;justify-content:space-between;gap:13px;padding:15px 0;border-bottom:1px solid var(--border)}.lesson:last-child{border-bottom:0}.lesson-left{display:flex;align-items:center;gap:12px}.lesson-num{width:37px;height:37px;border-radius:11px;display:grid;place-items:center;background:#f1efff;color:#5948d8;font-weight:850}
.chat-fab{position:fixed;right:22px;bottom:22px;z-index:60;border:0;background:linear-gradient(135deg,var(--primary),var(--teal));color:#fff;border-radius:999px;padding:13px 17px;box-shadow:0 13px 28px rgba(108,92,231,.3);font-weight:800}
.chat-shell{max-width:980px;margin:0 auto;background:var(--surface);border:1px solid var(--border);border-radius:20px;overflow:hidden;box-shadow:var(--shadow)}.chat-head{height:76px;padding:0 18px;border-bottom:1px solid var(--border);display:flex;align-items:center;gap:11px}.status-dot{width:8px;height:8px;border-radius:50%;background:#12b76a;display:inline-block}.chat-log{height:calc(100vh - 252px);min-height:420px;overflow:auto;padding:20px;background:linear-gradient(180deg,rgba(108,92,231,.025),transparent)}.msg{max-width:70%;padding:11px 13px;border-radius:15px;margin:7px 0;line-height:1.5;white-space:pre-wrap;overflow-wrap:anywhere}.msg.me{margin-left:auto;background:linear-gradient(135deg,var(--primary),#8b76f3);color:#fff;border-bottom-right-radius:5px}.msg.teacher{background:var(--surface-2);color:var(--text);border:1px solid var(--border);border-bottom-left-radius:5px}.msg small{display:block;font-size:11px;opacity:.67;margin-top:5px}.chat-empty{height:100%;display:grid;place-items:center;color:var(--muted);text-align:center;padding:30px}.chat-compose{display:flex;gap:9px;padding:13px;border-top:1px solid var(--border);background:var(--surface)}.chat-compose .input{flex:1}
.profile-grid{display:grid;grid-template-columns:315px minmax(0,1fr);gap:20px}.profile-card{text-align:center}.avatar-xl{width:104px;height:104px;border-radius:50%;margin:6px auto 15px;display:grid;place-items:center;background:linear-gradient(135deg,var(--primary),var(--teal));color:#fff;font-size:32px;font-weight:850}.teacher-access{margin-top:18px;text-align:left;background:linear-gradient(135deg,#f8f7ff,#effcf9);border:1px solid #e5e1ff;border-radius:17px;padding:18px}.dark .teacher-access{background:linear-gradient(135deg,#1b1831,#132925);border-color:#342d5c}.teacher-access img{width:100%;max-height:150px;object-fit:contain;margin-bottom:8px}
.settings-group{margin-bottom:19px}.settings-group h4{margin:0 0 11px}
.modal-backdrop{position:fixed;inset:0;background:rgba(16,24,40,.58);backdrop-filter:blur(4px);z-index:100;display:grid;place-items:center;padding:18px}.modal{width:min(430px,100%);background:var(--surface);border:1px solid var(--border);border-radius:20px;padding:24px;box-shadow:0 24px 60px rgba(0,0,0,.24)}.modal h3{margin-top:0}.modal-actions{display:flex;justify-content:flex-end;gap:9px;margin-top:18px}
.table-wrap{overflow:auto}.table{width:100%;border-collapse:collapse;min-width:720px}.table th,.table td{text-align:left;padding:12px;border-bottom:1px solid var(--border);font-size:13px}.table th{font-size:11px;text-transform:uppercase;letter-spacing:.6px;color:var(--muted)}.table tr:hover td{background:var(--surface-2)}
.teacher-layout{min-height:100vh;background:var(--bg)}.teacher-sidebar{position:fixed;inset:0 auto 0 0;width:250px;background:#101828;color:#fff;padding:20px 14px;z-index:40}.teacher-sidebar .brand img{width:165px;filter:brightness(0) invert(1)}.teacher-sidebar .side-label{color:#98a2b3;margin-top:20px}.teacher-sidebar .side-link{color:#b8c0cc}.teacher-sidebar .side-link:hover,.teacher-sidebar .side-link.active{background:#1d2939;color:#fff}.teacher-main{margin-left:250px}.teacher-topbar{height:72px;background:var(--surface);border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;padding:0 25px;position:sticky;top:0;z-index:25}.teacher-content{padding:25px}.teacher-panel{display:none}.teacher-panel.active{display:block}.teacher-kicker{font-size:12px;color:var(--primary);font-weight:850;text-transform:uppercase;letter-spacing:1px;margin-bottom:7px}.teacher-title{font-size:30px;letter-spacing:-.8px;margin:0}.teacher-sub{color:var(--muted);margin:7px 0 22px}
.inbox-layout{display:grid;grid-template-columns:330px minmax(0,1fr);gap:16px;height:calc(100vh - 147px)}.conversation-list{background:var(--surface);border:1px solid var(--border);border-radius:18px;overflow:hidden;display:flex;flex-direction:column}.conversation-list-head{padding:15px;border-bottom:1px solid var(--border)}.conversation-scroll{overflow:auto}.conversation-item{padding:13px 14px;border-bottom:1px solid var(--border);cursor:pointer;display:flex;gap:10px;align-items:flex-start}.conversation-item:hover,.conversation-item.active{background:var(--surface-2)}.conversation-item.active{box-shadow:inset 3px 0 0 var(--primary)}.conversation-meta{min-width:0;flex:1}.conversation-meta b{display:block;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.conversation-preview{font-size:12px;color:var(--muted);white-space:nowrap;overflow:hidden;text-overflow:ellipsis;margin-top:3px}.unread-badge{min-width:20px;height:20px;padding:0 6px;border-radius:999px;background:var(--primary);color:#fff;font-size:11px;font-weight:850;display:grid;place-items:center}
.teacher-chat{background:var(--surface);border:1px solid var(--border);border-radius:18px;overflow:hidden;display:flex;flex-direction:column}.teacher-chat-head{height:69px;padding:0 16px;border-bottom:1px solid var(--border);display:flex;align-items:center;gap:10px}.teacher-chat-log{flex:1;overflow:auto;padding:18px}.teacher-chat-compose{display:flex;gap:9px;padding:12px;border-top:1px solid var(--border)}
.badge-row{display:flex;gap:7px;flex-wrap:wrap}.empty-state{padding:40px;text-align:center;color:var(--muted)}.empty-state .big{font-size:42px;margin-bottom:8px}
.announcement{padding:16px;border:1px solid var(--border);border-radius:14px;background:var(--surface-2)}.announcement h4{margin:0 0 6px}.announcement p{margin:0;line-height:1.6}.announcement small{display:block;color:var(--muted);margin-top:7px}
.toast{position:fixed;right:22px;top:88px;z-index:200;background:#101828;color:white;padding:12px 16px;border-radius:12px;box-shadow:var(--shadow);opacity:0;transform:translateY(-8px);pointer-events:none;transition:.2s}.toast.show{opacity:1;transform:translateY(0)}
.mobile-menu{display:none}
@media(max-width:1020px){
.hero-grid,.auth-wrap,.profile-grid{grid-template-columns:1fr}.auth-side{display:none}.grid-3{grid-template-columns:1fr 1fr}.grid-4,.stats{grid-template-columns:1fr 1fr}
.sidebar{transform:translateX(-100%);transition:.2s}.sidebar.open{transform:translateX(0)}.main{margin-left:0}.mobile-menu{display:grid}
.teacher-sidebar{transform:translateX(-100%);transition:.2s}.teacher-sidebar.open{transform:translateX(0)}.teacher-main{margin-left:0}.inbox-layout{grid-template-columns:290px minmax(0,1fr)}
}
@media(max-width:700px){
.container{width:min(100% - 26px,1180px)}.navlinks{display:none}.hero{padding:52px 0}.hero h1{letter-spacing:-2px}.grid-2,.grid-3,.grid-4,.stats{grid-template-columns:1fr}.section{padding:52px 0}
.content,.teacher-content{padding:17px}.appbar,.teacher-topbar{padding:0 14px}.welcome{align-items:flex-start;flex-direction:column;padding:22px}.welcome h1{font-size:27px}.course-card img{height:190px}
.auth-main{padding:17px}.auth-card{padding:23px 19px}.chat-log{height:calc(100vh - 225px);min-height:360px}.msg{max-width:87%}
.inbox-layout{grid-template-columns:1fr;height:auto}.conversation-list{max-height:300px}.teacher-chat{height:560px}.teacher-title{font-size:26px}
}

.toast[data-type="error"]{background:#b42318}
.auth-card .success{color:#027a48}
.system-value{overflow-wrap:anywhere}