Checkbox in the form of a circle with a mark in the form of a bird inside

checked cirсle

// Non-standard checkbox type: circle + birdie marker
// Подробнее - https://paulund.co.uk/how-to-style-a-checkbox-with-css

			input[type="checkbox"] {
				position: absolute;
				opacity: 0;
				+ label {
					position: relative;
					cursor: pointer;
					padding: 0 0 0 22px;
					margin-bottom: 0;
					opacity: 1;
					a {
						opacity: 0.3;
					}
					&:before {
						content: '';
						position: absolute;
						left: 0;
						top: 5px;
						width: 14px;
						height: 14px;
						border-radius: 100%;
						border: 1px solid #fff;
						opacity: 0.3;
						background: transparent;
						box-shadow:inset 0 2px 3px rgba(0,0,0,.2);
					}
					&:after {
						content: "";
						position: absolute;
					}
				}
				&:checked {
					+ label:after {
						content: "√";
						position: absolute;
						opacity: 0.7;
						color: #fff;
						font-size: 24px;
						top: -1px;
						left: 1px;	
					}
				}
			} // end input[type="checkbox"]