body {
    display: flex;
    min-height: 100vh;
    flex-direction: column;
}
main {
    flex: 1;
}
footer {
    background: #f8f9fa;
    padding: 1rem 0;
    text-align: center;
}
#container{
width:960px;
height:400px;
background:#ccc;
margin:0 auto;
}

#help_panel{
position:absolute;
left:0;
right:0;

background:red;
color:white;
}
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    z-index: 9999;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    color: #fff;
    font-size: 1.5em;
    text-align: center;
}
.spinner {
    width: 50px;
    height: 50px;
    border: 8px solid rgba(255, 255, 255, 0.3);
    border-top: 8px solid #fff;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 20px;
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}
.blur {
    filter: blur(5px);
}