:root{
  --brand:#4f46e5;
  --brand-600:#4338ca;
  --bg:#f4f6fb;
  --card:#ffffff;
  --ink:#1f2430;
  --muted:#6b7280;
  --line:#e6e8ef;
  --sidebar-w:264px;
  --radius:16px;
  --shadow:0 6px 24px rgba(20,23,40,.06);
  --shadow-lg:0 12px 40px rgba(20,23,40,.12);
}
*{box-sizing:border-box}
body{
  margin:0;font-family:'Segoe UI',system-ui,-apple-system,Roboto,Helvetica,Arial,sans-serif;
  background:var(--bg);color:var(--ink);font-size:15px;
}
a{text-decoration:none;color:var(--brand)}
.brand-gradient{background:linear-gradient(135deg,var(--brand),#7c3aed)}

/* ---------- Layout ---------- */
.app-layout{display:flex;min-height:100vh}
.app-main{flex:1;display:flex;flex-direction:column;min-width:0}

/* ---------- Sidebar ---------- */
.sidebar{
  width:var(--sidebar-w);flex-shrink:0;background:#0f1222;color:#c9cddb;
  display:flex;flex-direction:column;position:sticky;top:0;height:100vh;
}
.sidebar-brand{display:flex;align-items:center;gap:12px;padding:22px 20px;font-weight:700;color:#fff;font-size:1.05rem}
.brand-mark{width:38px;height:38px;border-radius:11px;display:grid;place-items:center;background:linear-gradient(135deg,var(--brand),#7c3aed);font-size:1.2rem;color:#fff}
.brand-logo{width:38px;height:38px;border-radius:11px;object-fit:cover;background:#fff}
.brand-text{white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.sidebar-nav{flex:1;overflow-y:auto;padding:8px 12px;display:flex;flex-direction:column;gap:2px}
.sidebar-nav a{display:flex;align-items:center;gap:12px;padding:11px 14px;border-radius:12px;color:#aab0c4;font-weight:500;transition:.15s}
.sidebar-nav a i{font-size:1.15rem;width:22px;text-align:center}
.sidebar-nav a:hover{background:rgba(255,255,255,.06);color:#fff}
.sidebar-nav a.active{background:linear-gradient(135deg,var(--brand),#7c3aed);color:#fff;box-shadow:0 6px 18px rgba(79,70,229,.4)}
.sidebar-section{padding:16px 14px 6px;font-size:.72rem;letter-spacing:.08em;text-transform:uppercase;color:#5b6178;font-weight:700}
.sidebar-footer{padding:14px 12px;border-top:1px solid rgba(255,255,255,.06)}
.sidebar-footer a{display:flex;align-items:center;gap:12px;padding:10px 14px;border-radius:12px;font-weight:500}
.sidebar-footer a:hover{background:rgba(239,68,68,.12)}

/* ---------- Topbar ---------- */
.topbar{display:flex;align-items:center;gap:14px;padding:16px 26px;background:var(--card);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:20}
.topbar-title{font-size:1.25rem;font-weight:700;margin:0;flex:1}
.topbar-right{display:flex;align-items:center;gap:14px}
.btn-icon{background:transparent;border:none;font-size:1.5rem;color:var(--ink);cursor:pointer}
.user-chip{display:flex;align-items:center;gap:10px;background:var(--bg);border:1px solid var(--line);border-radius:999px;padding:5px 14px 5px 6px;cursor:pointer;font-weight:600;color:var(--ink)}
.avatar-sm{width:32px;height:32px;border-radius:50%;background:linear-gradient(135deg,var(--brand),#7c3aed);color:#fff;display:grid;place-items:center;font-weight:700;overflow:hidden}
.avatar-sm img{width:100%;height:100%;object-fit:cover}

/* ---------- Content ---------- */
.content{padding:26px;flex:1}
.app-footer{padding:18px 26px;color:var(--muted);font-size:.85rem;border-top:1px solid var(--line);background:var(--card)}

/* ---------- Cards ---------- */
.card{border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);background:var(--card)}
.card-header{background:transparent;border-bottom:1px solid var(--line);font-weight:700;padding:16px 20px}
.card-body{padding:20px}

/* ---------- Stat cards ---------- */
.stat-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:18px}
.stat-card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:20px;box-shadow:var(--shadow);display:flex;align-items:center;gap:16px;transition:.2s}
.stat-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg)}
.stat-ico{width:52px;height:52px;border-radius:14px;display:grid;place-items:center;font-size:1.5rem;color:#fff;flex-shrink:0}
.stat-card .value{font-size:1.7rem;font-weight:800;line-height:1}
.stat-card .label{color:var(--muted);font-size:.85rem;margin-top:4px}
.bg-indigo{background:linear-gradient(135deg,#4f46e5,#7c3aed)}
.bg-green{background:linear-gradient(135deg,#059669,#10b981)}
.bg-amber{background:linear-gradient(135deg,#d97706,#f59e0b)}
.bg-rose{background:linear-gradient(135deg,#e11d48,#f43f5e)}
.bg-sky{background:linear-gradient(135deg,#0284c7,#0ea5e9)}

/* ---------- Course cards ---------- */
.course-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:20px}
.course-card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow);transition:.2s;display:flex;flex-direction:column}
.course-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg)}
.course-cover{position:relative;height:150px;overflow:hidden;background:linear-gradient(135deg,var(--brand),#7c3aed);display:flex;align-items:center;justify-content:center;color:#fff;font-size:2.6rem;flex:0 0 auto}
.course-cover img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;display:block}
.course-body{position:relative;background:var(--card);padding:18px;flex:1;display:flex;flex-direction:column;min-height:0}
.course-body h3{font-size:1.05rem;margin:0 0 6px;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}
.course-body p{color:var(--muted);font-size:.88rem;flex:1;display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden}
.progress{height:8px;border-radius:999px;background:var(--line)}
.progress-bar{background:linear-gradient(135deg,var(--brand),#7c3aed)}

/* ---------- Buttons ---------- */
.btn-primary{background:var(--brand);border-color:var(--brand)}
.btn-primary:hover{background:var(--brand-600);border-color:var(--brand-600)}
.btn-outline-primary{color:var(--brand);border-color:var(--brand)}
.btn-outline-primary:hover{background:var(--brand);border-color:var(--brand)}
.btn{border-radius:11px;font-weight:600;padding:.5rem 1rem}
.btn-sm{border-radius:9px}

/* ---------- Tables ---------- */
.table{--bs-table-bg:transparent;vertical-align:middle}
.table thead th{color:var(--muted);font-size:.78rem;letter-spacing:.04em;text-transform:uppercase;border-bottom:2px solid var(--line)}
.badge-soft{padding:.4em .7em;border-radius:8px;font-weight:600;font-size:.75rem}
.badge-active{background:#dcfce7;color:#166534}
.badge-inactive{background:#fee2e2;color:#991b1b}
.badge-admin{background:#ede9fe;color:#5b21b6}
.badge-user{background:#e0f2fe;color:#075985}

/* ---------- Lesson viewer ---------- */
.lesson-list .lesson-item{display:flex;align-items:center;gap:14px;padding:14px 16px;border:1px solid var(--line);border-radius:12px;margin-bottom:10px;background:var(--card);transition:.15s}
.lesson-list .lesson-item:hover{border-color:var(--brand);box-shadow:var(--shadow)}
.lesson-ico{width:42px;height:42px;border-radius:11px;display:grid;place-items:center;background:var(--bg);color:var(--brand);font-size:1.2rem;flex-shrink:0}
.lesson-done{color:#10b981}
.viewer-frame{width:100%;min-height:70vh;border:1px solid var(--line);border-radius:12px}
.viewer-media{width:100%;border-radius:12px;background:#000}

/* ---------- Visor de PDF (PDF.js) ---------- */
.pdf-viewer{border:1px solid var(--line);border-radius:12px;overflow:hidden;background:#525659}
.pdf-toolbar{display:flex;align-items:center;gap:8px;flex-wrap:wrap;padding:8px 10px;background:#f8f9fb;border-bottom:1px solid var(--line)}
.pdf-toolbar .btn{--bs-btn-padding-y:.2rem;--bs-btn-padding-x:.5rem}
.pdf-pages{max-height:78vh;overflow:auto;-webkit-overflow-scrolling:touch;padding:14px;display:flex;flex-direction:column;align-items:center;gap:14px}
.pdf-page{height:auto;background:#fff;border-radius:4px;box-shadow:0 4px 16px rgba(0,0,0,.35)}
.pdf-ph{width:100%;max-width:900px;display:flex;align-items:center;justify-content:center;background:#6b6f76;border-radius:4px;color:#fff}
.pdf-fallback{padding:32px 20px;text-align:center;color:#fff}

/* ---------- Visor de Office (carga diferida) ---------- */
.office-embed{border:1px solid var(--line);border-radius:12px;overflow:hidden;background:#fff}
.office-ph{padding:40px 20px;text-align:center}
.office-ph i{font-size:3rem;color:var(--brand)}
.office-loading{padding:40px 20px;text-align:center;color:var(--muted)}
@media (max-width:576px){
  .pdf-pages{max-height:70vh;padding:8px}
  .pdf-toolbar #pdfInfo{width:100%;order:-1}
}

/* ---------- Auth pages ---------- */
.auth-wrap{min-height:100vh;display:grid;place-items:center;padding:24px;background:linear-gradient(135deg,#0f1222,#312e81)}
.auth-card{width:100%;max-width:430px;background:var(--card);border-radius:22px;box-shadow:var(--shadow-lg);padding:38px 34px}
.auth-logo{width:64px;height:64px;border-radius:18px;display:grid;place-items:center;margin:0 auto 18px;background:linear-gradient(135deg,var(--brand),#7c3aed);color:#fff;font-size:1.8rem}
.auth-logo img{width:100%;height:100%;object-fit:cover;border-radius:18px}
.auth-card h1{font-size:1.4rem;text-align:center;margin:0 0 4px}
.auth-card .sub{text-align:center;color:var(--muted);margin-bottom:26px}
.form-control,.form-select{border-radius:11px;padding:.6rem .85rem;border-color:var(--line)}
.form-control:focus,.form-select:focus{border-color:var(--brand);box-shadow:0 0 0 .2rem rgba(79,70,229,.15)}
.form-label{font-weight:600;font-size:.88rem}

/* ---------- Empty state ---------- */
.empty{text-align:center;padding:60px 20px;color:var(--muted)}
.empty i{font-size:3rem;opacity:.4;display:block;margin-bottom:12px}

/* ---------- Responsive ---------- */
.sidebar-backdrop{display:none}
@media (max-width:991.98px){
  .sidebar{position:fixed;left:0;top:0;z-index:1050;transform:translateX(-100%);transition:transform .25s;box-shadow:var(--shadow-lg)}
  .sidebar.open{transform:translateX(0)}
  .sidebar-backdrop.show{display:block;position:fixed;inset:0;background:rgba(0,0,0,.4);z-index:1040}
}
@media (max-width:575.98px){
  .content{padding:16px}
  .topbar{padding:14px 16px}
}