canvas{ 
  display: block; 
  vertical-align: bottom; 
} 
#particles-js{ 
  position:absolute; 
  width: 100%; 
  height: 100%; 
  background-color: #ffffff; 
  background-repeat: no-repeat; 
  background-size: cover; 
  background-position: 50% 50%; 
  inset: 0;
  z-index: 0;
}
.polygon-bg {
  position: relative;
  min-height: 60vh;     /*最低限の見た目を確保 */
  padding: 40px 0px; /* ← 高さは中身で決まる */
  overflow: hidden;
}
.polygon-bg-content {
  position: relative;
  z-index: 1;
} 
#mainContent-fd {
	width: 100%;
	/*max-width: 1100px;*/
	margin-left: auto;
	margin-right: auto;	
}
div.h2-fd {
	margin-bottom:0;
}
footer {
	margin-top:0px;
}