:root{
  --bg:#f6f8fb;
  --card:#ffffff;
  --muted:#6b7280;
  --accent:#2563eb;
  --accent-600:#1e40af;
  --success:#16a34a;
  --danger:#ef4444;
  --glass: rgba(255,255,255,0.6);
  --radius:12px;
  --shadow: 0 6px 18px rgba(16,24,40,0.06);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
  color-scheme: light;
}

*{box-sizing:border-box;}
html,body{height:100%;}
body{
  margin:0;
  background:linear-gradient(180deg, var(--bg) 0%, #eef2ff 100%);
  color:#0f172a;
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
  line-height:1.4;
}

.container{
  max-width:1000px;
  margin:0 auto;
  padding:20px;
}

/* Header */
.site-header{
  background:transparent;
  padding:14px 0;
  border-bottom:1px solid rgba(15,23,42,0.04);
  backdrop-filter: blur(6px);
}
.brand{
  margin:0;
  display:inline-block;
  font-weight:600;
  font-size:20px;
  color:var(--accent-600);
}
.site-header .container{display:flex;align-items:center;justify-content:space-between;}

/* Footer */
.site-footer{
  margin-top:40px;
  padding:16px 0;
  text-align:center;
  color:var(--muted);
  font-size:13px;
}

/* Buttons */
.btn{
  display:inline-flex;
  align-items:center;
  gap:8px;
  padding:8px 12px;
  border-radius:8px;
  background:var(--accent);
  color:#fff;
  border:none;
  cursor:pointer;
  font-weight:600;
  transition: transform .12s ease, box-shadow .12s ease, background-color .12s ease;
  box-shadow: 0 6px 14px rgba(37,99,235,0.12);
}
.btn:hover{ transform: translateY(-2px); box-shadow: 0 10px 22px rgba(37,99,235,0.14); }
.btn:active{ transform: translateY(0); }

.btn-ghost{
  background:transparent;
  color:var(--accent-600);
  box-shadow:none;
  padding:6px 10px;
  border-radius:8px;
  border:1px solid transparent;
}
.btn-ghost:hover{ background:rgba(37,99,235,0.06); box-shadow:none; transform:none; }

/* Layout - home grid */
.grid{
  display:grid;
  grid-template-columns: repeat(auto-fill, minmax(260px,1fr));
  gap:18px;
  margin-top:18px;
}

/* Course Card */
.card{
  background:var(--card);
  border-radius:var(--radius);
  padding:16px;
  box-shadow:var(--shadow);
  display:flex;
  flex-direction:column;
  gap:12px;
  transition: transform .12s ease, box-shadow .12s ease;
  cursor:pointer;
}
.card:hover{
  transform: translateY(-6px);
  box-shadow: 0 18px 40px rgba(16,24,40,0.08);
}

.card .meta{
  display:flex;
  justify-content:space-between;
  align-items:center;
}
.card h3{ margin:0; font-size:16px; }
.card p{ margin:0; color:var(--muted); font-size:13px; }

/* Progress bar */
.progress-wrap{
  background:linear-gradient(90deg,#f3f4f6,#f8fafc);
  border-radius:999px;
  height:10px;
  overflow:hidden;
}
.progress{
  height:100%;
  background:linear-gradient(90deg,var(--accent),#7c3aed);
  width:0%;
  transition: width 320ms ease;
}

/* Small badge */
.badge{
  display:inline-flex;
  align-items:center;
  gap:8px;
  padding:6px 10px;
  border-radius:999px;
  font-weight:600;
  font-size:12px;
}
.badge.success{ background:rgba(22,163,74,0.12); color:var(--success); }
.badge.pulse{
  animation: pulse 1600ms infinite;
}
@keyframes pulse{
  0%{ box-shadow:0 0 0 0 rgba(37,99,235,0.12); }
  70%{ box-shadow:0 0 0 10px rgba(37,99,235,0); }
  100%{ box-shadow:0 0 0 0 rgba(37,99,235,0); }
}

/* Detail view */
.detail{
  display:grid;
  grid-template-columns: 1fr 320px;
  gap:18px;
  margin-top:18px;
}
.panel{
  background:var(--card);
  padding:16px;
  border-radius:12px;
  box-shadow:var(--shadow);
}
.lessons{ display:flex; flex-direction:column; gap:8px; }
.lesson{
  display:flex;
  gap:12px;
  align-items:center;
  padding:10px;
  border-radius:8px;
  transition: background .12s ease;
}
.lesson:hover{ background:rgba(15,23,42,0.02); }
.lesson .title{ font-weight:600; }
.lesson .meta{ font-size:13px; color:var(--muted); }

/* Smaller utilities */
.row{ display:flex; gap:12px; align-items:center; }
.space-between{ display:flex; justify-content:space-between; align-items:center; }
.muted{ color:var(--muted); font-size:13px; }
.small{ font-size:13px; }

.empty{
  text-align:center;
  color:var(--muted);
  padding:36px;
  border-radius:10px;
  background:linear-gradient(180deg, rgba(255,255,255,0.6), rgba(255,255,255,0.4));
}

/* Responsive */
@media (max-width:880px){
  .detail{ grid-template-columns: 1fr; }
  .card{ cursor:default; }
}