* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: #0d1117;
  color: #fff;
}
.hidden { display: none !important; }
.center {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}
.card {
  background: #161b22;
  border: 1px solid #30363d;
  border-radius: 16px;
  padding: 20px;
  box-shadow: 0 10px 30px rgba(0,0,0,.25);
}
.login-card { width: 100%; max-width: 420px; }
input, textarea {
  width: 100%;
  margin: 8px 0;
  padding: 13px;
  border: 1px solid #30363d;
  border-radius: 10px;
  background: #0d1117;
  color: #fff;
  outline: none;
}
textarea { min-height: 80px; resize: vertical; }
button {
  width: 100%;
  margin-top: 10px;
  padding: 13px;
  border: 0;
  border-radius: 10px;
  background: #238636;
  color: white;
  font-size: 16px;
  font-weight: bold;
  cursor: pointer;
}
button:hover { filter: brightness(1.1); }
button.secondary { background: #30363d; width: auto; padding: 10px 16px; }
button.danger { background: #da3633; }
button.warn { background: #8957e5; }
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 20px;
  background: #161b22;
  border-bottom: 1px solid #30363d;
}
header h2 { margin: 0; }
main { padding: 20px; max-width: 1200px; margin: auto; }
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 15px;
  margin-bottom: 15px;
}
.videos {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(290px, 1fr));
  gap: 16px;
}
.video-card h3 { margin-top: 0; }
.video-box {
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #000;
  border-radius: 12px;
  overflow: hidden;
  margin: 12px 0;
}
.video-box video, .video-box iframe {
  width: 100%;
  height: 100%;
  border: 0;
}
.user-row {
  display: grid;
  grid-template-columns: 1fr auto auto;
  gap: 8px;
  align-items: center;
  border-top: 1px solid #30363d;
  padding: 12px 0;
}
.user-row button { width: auto; margin: 0; padding: 8px 10px; font-size: 13px; }
.muted { color: #8b949e; }
.small { font-size: 13px; }
.hint {
  margin-top: 16px;
  background: #0d1117;
  border: 1px dashed #30363d;
  border-radius: 12px;
  padding: 12px;
  color: #c9d1d9;
  font-size: 14px;
}
.msg { color: #ff7b72; min-height: 20px; }
@media (max-width: 600px) {
  header { gap: 10px; }
  .user-row { grid-template-columns: 1fr; }
  button.secondary { width: 100%; }
}