/* WoWoChinese Video Lecture — Business UI */
:root{
  --primary:#2563eb; --primary-h:#1d4ed8; --primary-l:#eff6ff;
  --border:#e2e8f0; --bg:#f1f5f9; --card:#fff;
  --sidebar-bg:#f8fafc; --sidebar-text:#475569; --sidebar-active:#2563eb;
  --text1:#1e293b; --text2:#475569; --text3:#94a3b8;
  --success:#16a34a; --danger:#dc2626; --warn:#d97706;
  --radius:6px; --shadow:0 1px 3px rgba(0,0,0,.08);
}
*{box-sizing:border-box;margin:0;padding:0;}
body{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI','Noto Sans KR',sans-serif;
     font-size:14px;color:var(--text1);background:var(--bg);}

/* ── Layout ── */
.app{display:flex;height:100vh;overflow:hidden;}
.sidebar{width:220px;background:var(--sidebar-bg);display:flex;flex-direction:column;
         flex-shrink:0;overflow-y:auto;transition:width .2s ease,overflow .2s;}
.sidebar.collapsed{width:0;overflow:hidden;border-right:none;}

/* 사이드바 토글 버튼 */
.sb-collapse-btn{background:none;border:1px solid var(--border);border-radius:4px;
                  cursor:pointer;font-size:11px;color:var(--text3);padding:3px 6px;
                  flex-shrink:0;transition:all .1s;line-height:1;}
.sb-collapse-btn:hover{background:var(--border);color:var(--text1);}
.sb-show-btn{display:flex;align-items:center;justify-content:center;
             background:#fff;border:1px solid var(--border);border-radius:var(--radius);
             cursor:pointer;font-size:15px;color:var(--text2);padding:4px 8px;
             transition:all .1s;line-height:1;}
.sb-show-btn:hover{background:var(--bg);}
.main{flex:1;display:flex;flex-direction:column;overflow:hidden;}
.topbar{background:#fff;border-bottom:1px solid var(--border);padding:0 24px;
        height:52px;display:flex;align-items:center;justify-content:space-between;flex-shrink:0;}
.content{flex:1;overflow-y:auto;padding:24px;}

/* ── Sidebar ── */
.sidebar{border-right:1px solid var(--border);background:#fff;}
.sidebar-brand{padding:16px 18px;border-bottom:1px solid var(--border);
               display:flex;align-items:center;gap:8px;justify-content:space-between;
               background:#fff;}
.sidebar-brand .name{font-size:13px;font-weight:700;color:var(--primary);}
.sidebar-brand .sub{font-size:11px;color:var(--text3);margin-top:2px;}
.sidebar-nav{padding:8px 0;flex:1;}
.nav-section{padding:8px 8px 4px;margin:2px 6px 0;font-size:11px;font-weight:700;
             color:var(--text3);letter-spacing:.06em;text-transform:uppercase;}
/* ── 기본 메뉴 아이템 ── */
.nav-item{display:flex;align-items:center;gap:8px;padding:7px 12px;
          margin:1px 6px;border-radius:var(--radius);
          color:#374151;text-decoration:none;font-size:13px;
          transition:background .12s,color .12s;cursor:pointer;
          border-left:3px solid transparent;}
/* hover: 살짝 회색 배경, 진한 텍스트 */
.nav-item:hover{background:#f3f4f6;color:#111827;}
/* active: 파란 배경 + 왼쪽 강조선 */
.nav-item.active{
    background:#eff6ff;
    color:#1d4ed8;
    font-weight:600;
    border-left:3px solid #2563eb;
}
/* active 상태에서 hover해도 그대로 유지 */
.nav-item.active:hover{background:#dbeafe;color:#1d4ed8;}
.nav-item .icon{font-size:15px;width:18px;text-align:center;flex-shrink:0;}
.sidebar-footer{padding:14px 18px;border-top:1px solid var(--border);
                font-size:12px;background:#fff;}
.sidebar-footer .teacher-name{color:var(--text1);font-weight:600;}
.sidebar-footer .teacher-role{color:var(--text3);font-size:11px;margin-top:2px;}

/* ── Topbar ── */
.topbar-title{font-size:14px;font-weight:600;color:var(--text1);}
.topbar-right{display:flex;align-items:center;gap:12px;}
.topbar-user{font-size:12px;color:var(--text2);}
.topbar-logout{font-size:12px;color:var(--text3);text-decoration:none;
               padding:4px 10px;border:1px solid var(--border);border-radius:var(--radius);
               transition:all .1s;}
.topbar-logout:hover{background:var(--bg);color:var(--text1);}

/* ── Cards ── */
.card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);
      box-shadow:var(--shadow);margin-bottom:16px;}
.card-header{padding:14px 18px;border-bottom:1px solid var(--border);
             display:flex;align-items:center;justify-content:space-between;}
.card-title{font-size:13px;font-weight:600;color:var(--text1);}
.card-body{padding:16px 18px;}
.card-footer{padding:12px 18px;border-top:1px solid var(--border);background:#fafafa;}

/* ── Stat Grid ── */
.stat-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(160px,1fr));gap:14px;margin-bottom:20px;}
.stat-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);
           padding:16px 18px;box-shadow:var(--shadow);}
.stat-label{font-size:11px;font-weight:600;color:var(--text3);text-transform:uppercase;
            letter-spacing:.05em;margin-bottom:8px;}
.stat-value{font-size:24px;font-weight:700;color:var(--text1);}
.stat-sub{font-size:11px;color:var(--text3);margin-top:3px;}

/* ── Tables ── */
.table-wrap{overflow-x:auto;}
table.data-table{width:100%;border-collapse:collapse;font-size:13px;}
table.data-table th{background:var(--bg);padding:9px 12px;text-align:left;
                    font-weight:600;font-size:11px;text-transform:uppercase;
                    letter-spacing:.04em;color:var(--text3);border-bottom:1px solid var(--border);}
table.data-table td{padding:10px 12px;border-bottom:1px solid #f1f5f9;
                    color:var(--text1);vertical-align:middle;}
table.data-table tr:last-child td{border-bottom:none;}
table.data-table tr:hover td{background:#fafafa;}

/* ── Buttons ── */
.btn{display:inline-flex;align-items:center;gap:5px;padding:7px 14px;border-radius:var(--radius);
     font-size:13px;font-weight:500;cursor:pointer;border:none;transition:all .1s;text-decoration:none;}
.btn-primary{background:var(--primary);color:#fff;}
.btn-primary:hover{background:var(--primary-h);}
.btn-secondary{background:var(--bg);color:var(--text2);border:1px solid var(--border);}
.btn-secondary:hover{background:var(--border);color:var(--text1);}
.btn-danger{background:var(--danger);color:#fff;}
.btn-success{background:var(--success);color:#fff;}
.btn-sm{padding:4px 10px;font-size:12px;}
.btn-xs{padding:3px 8px;font-size:11px;}

/* ── Badges ── */
.badge{padding:2px 8px;border-radius:10px;font-size:11px;font-weight:600;display:inline-block;}
.badge-ok{background:#f0fdf4;color:#166534;border:1px solid #bbf7d0;}
.badge-warn{background:#fffbeb;color:#92400e;border:1px solid #fde68a;}
.badge-danger{background:#fef2f2;color:#991b1b;border:1px solid #fecaca;}
.badge-blue{background:var(--primary-l);color:var(--primary);border:1px solid #bfdbfe;}
.badge-gray{background:var(--bg);color:var(--text2);border:1px solid var(--border);}

/* ── Forms ── */
.form-group{margin-bottom:14px;}
.form-label{display:block;font-size:12px;font-weight:600;color:var(--text2);margin-bottom:5px;}
.form-control{width:100%;border:1px solid var(--border);border-radius:var(--radius);
              padding:8px 11px;font-size:13px;outline:none;background:#fff;
              color:var(--text1);transition:border-color .15s;}
.form-control:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.06);}
select.form-control{cursor:pointer;}
textarea.form-control{resize:vertical;min-height:80px;}

/* ── Progress Bar ── */
.progress-bar{background:var(--border);border-radius:4px;height:8px;overflow:hidden;}
.progress-fill{height:100%;background:var(--primary);border-radius:4px;transition:width .3s;}

/* ── Utilities ── */
.text-muted{color:var(--text3);}
.text-primary{color:var(--primary);}
.text-success{color:var(--success);}
.text-danger{color:var(--danger);}
.fw-600{font-weight:600;}
.flex{display:flex;} .flex-1{flex:1;} .items-center{align-items:center;}
.justify-between{justify-content:space-between;} .gap-2{gap:8px;} .gap-3{gap:12px;}
.flex-wrap{flex-wrap:wrap;}
.mb-4{margin-bottom:16px;} .mt-2{margin-top:8px;} .mt-4{margin-top:16px;}
.grid-2{display:grid;grid-template-columns:1fr 1fr;gap:14px;}
.grid-3{display:grid;grid-template-columns:1fr 1fr 1fr;gap:14px;}

/* ── Alert ── */
.alert{padding:12px 16px;border-radius:var(--radius);font-size:13px;margin-bottom:14px;}
.alert-error{background:#fef2f2;color:#991b1b;border:1px solid #fecaca;}
.alert-success{background:#f0fdf4;color:#166534;border:1px solid #bbf7d0;}

/* ── Modal overlay ── */
.modal-overlay{position:fixed;inset:0;background:rgba(0,0,0,.5);z-index:9000;
               display:flex;align-items:center;justify-content:center;}
.modal{background:#fff;border-radius:10px;width:90%;max-width:520px;
       max-height:90vh;overflow-y:auto;box-shadow:0 8px 32px rgba(0,0,0,.15);}
.modal-header{padding:16px 20px;border-bottom:1px solid var(--border);
              display:flex;align-items:center;justify-content:space-between;}
.modal-title{font-size:15px;font-weight:700;}
.modal-close{background:none;border:none;font-size:20px;cursor:pointer;color:var(--text3);}
.modal-body{padding:20px;}
.modal-footer{padding:14px 20px;border-top:1px solid var(--border);
              display:flex;justify-content:flex-end;gap:8px;}

/* ── Live dot ── */
.live-dot{display:inline-block;width:8px;height:8px;border-radius:50%;
          background:#dc2626;animation:pulse 1.5s infinite;vertical-align:middle;}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:.4}}

/* ── Responsive ── */
@media(max-width:768px){
  .sidebar{display:none;}
  .grid-2,.grid-3{grid-template-columns:1fr;}
  .content{padding:14px;}
}