:root{
  --edu-ink:#071b4d;
  --edu-blue:#0754d8;
  --edu-red:#ff2f57;
  --edu-line:#dbe7f5;
}

body.edu-activity-shell{
  margin:0;
  min-height:100vh;
  background:#f4fbff;
  color:var(--edu-ink);
  font-family:Arial, Helvetica, sans-serif;
}

.edu-shell-header{
  background:#fff;
  border-bottom:1px solid var(--edu-line);
  box-shadow:0 6px 18px rgba(7,27,77,.08);
  position:relative;
  z-index:30;
}

.edu-shell-bar{
  max-width:1500px;
  margin:0 auto;
  min-height:70px;
  padding:10px 22px;
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:18px;
}

.edu-shell-brand{
  display:flex;
  align-items:center;
  gap:12px;
  color:var(--edu-ink);
  min-width:220px;
}

.edu-shell-logo{
  width:46px;
  height:46px;
  border-radius:12px;
  background:linear-gradient(135deg,#ffffff,#eef6ff);
  border:1px solid #cfe0f4;
  display:flex;
  align-items:center;
  justify-content:center;
  font-size:27px;
  box-shadow:0 8px 18px rgba(7,27,77,.10);
}

.edu-shell-title strong{
  display:block;
  font-size:26px;
  line-height:1;
  letter-spacing:0;
}

.edu-shell-title span{
  display:block;
  margin-top:3px;
  color:var(--edu-red);
  font-weight:bold;
  font-size:14px;
}

.edu-shell-context{
  flex:1;
  min-width:240px;
  text-align:center;
  line-height:1.25;
}

.edu-shell-context strong{
  display:block;
  font-size:17px;
  color:var(--edu-ink);
}

.edu-shell-context span{
  display:block;
  margin-top:3px;
  font-size:13px;
  color:#526581;
  font-weight:bold;
}

.edu-shell-actions{
  display:flex;
  align-items:center;
  justify-content:flex-end;
  gap:10px;
  min-width:150px;
}

.edu-shell-actions a{
  color:var(--edu-ink);
  text-decoration:none;
  font-weight:bold;
  border-radius:999px;
  padding:10px 14px;
  line-height:1;
}

.edu-shell-actions .edu-primary{
  background:var(--edu-blue);
  color:#fff;
}

.edu-shell-actions .edu-danger{
  background:#ffe8ee;
  color:#c61135;
}

.edu-activity-main{
  max-width:1500px;
  margin:8px auto 0;
  padding:0 12px 8px;
  position:relative;
  z-index:5;
}

.edu-activity-frame{
  background:#fff;
  border:1px solid #dce8f7;
  border-radius:18px;
  box-shadow:0 18px 40px rgba(7,27,77,.16);
  padding:8px;
  overflow:hidden;
}

.edu-activity-frame .pcllim{
  margin-left:auto;
  margin-right:auto;
}

.edu-activity-scale{
  transform-origin:top center;
  margin-left:auto;
  margin-right:auto;
}

.edu-activity-frame.is-scaled{
  overflow:hidden;
}

.edu-activity-frame.is-scaled .pcllim{
  margin-left:0;
  margin-right:0;
}

.edu-shell-footer{
  background:#e8f2ff;
  border-top:1px solid #d7e6f7;
  color:#34476d;
  padding:10px 22px;
}

.edu-shell-footer-inner{
  max-width:1500px;
  margin:0 auto;
  display:grid;
  grid-template-columns:repeat(4,auto);
  justify-content:space-between;
  align-items:center;
  gap:14px;
  font-size:15px;
}

@media(max-width:850px){
  .edu-shell-bar{
    align-items:flex-start;
    flex-direction:column;
  }

  .edu-shell-context{
    text-align:left;
  }

  .edu-shell-actions{
    min-width:0;
    width:100%;
    justify-content:flex-start;
    flex-wrap:wrap;
  }

  .edu-shell-footer-inner{
    grid-template-columns:1fr;
  }
}

@media(max-width:560px){
  .edu-shell-bar{
    padding:12px 16px;
  }

  .edu-shell-title strong{
    font-size:22px;
  }

  .edu-shell-context{
    min-width:0;
  }

  .edu-activity-main{
    padding-left:8px;
    padding-right:8px;
  }

  .edu-activity-frame{
    border-radius:14px;
    padding:6px;
  }
}