<button class="ccb-corner" aria-label="Close modal"><span></span><span></span></button>

.ccb-corner {
  width: 48px; height: 48px;
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 50%;
  background: rgba(255,255,255,0.06);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
  position: relative; cursor: pointer; overflow: hidden;
  transition: background 0.25s, border-color 0.25s;
}
.ccb-corner::before {
  content: ''; position: absolute; inset: -50%;
  background: radial-gradient(circle at center, rgba(124,108,255,0.4) 0%, transparent 60%);
  opacity: 0; transition: opacity 0.3s;
}
.ccb-corner:hover { background: rgba(255,255,255,0.1); border-color: rgba(124,108,255,0.4); }
.ccb-corner:hover::before { opacity: 1; }
.ccb-corner span {
  position: absolute; top: 50%; left: 50%;
  width: 18px; height: 2px;
  background: #f0eeff; border-radius: 2px;
  z-index: 1;
  transition: background 0.25s, transform 0.3s;
}
.ccb-corner span:nth-child(1) { transform: translate(-50%,-50%) rotate(45deg); }
.ccb-corner span:nth-child(2) { transform: translate(-50%,-50%) rotate(-45deg); }
.ccb-corner:hover span { background: #fff; }
.ccb-corner:hover span:nth-child(1) { transform: translate(-50%,-50%) rotate(135deg); }
.ccb-corner:hover span:nth-child(2) { transform: translate(-50%,-50%) rotate(-135deg); }