A CSS file which uses the clip-path property, allowing you to make complex shapes in CSS basically using polygons. Summarized from https://bennettfeely.com/clippy/

clip-path.css

/**
 * CSS file created using Bennett Feely's clip-path generator <https://bennettfeely.com/clippy/>
 */

.clipped-parallelogram {
  -webkit-clip-path: polygon(25% 0%, 100% 0%, 75% 100%, 0% 100%);
  clip-path: polygon(25% 0%, 100% 0%, 75% 100%, 0% 100%);
}

.clipped-trapezoid {
  -webkit-clip-path: polygon(20% 0%, 80% 0%, 100% 100%, 0% 100%);
  clip-path: polygon(20% 0%, 80% 0%, 100% 100%, 0% 100%);
}

.clipped-diamond {
  -webkit-clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);
  clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);
}

.clipped-left {
  -webkit-clip-path: polygon(25% 0%, 100% 1%, 100% 100%, 25% 100%, 0% 50%);
  clip-path: polygon(25% 0%, 100% 1%, 100% 100%, 25% 100%, 0% 50%);
}

.clipped-right {
  -webkit-clip-path: polygon(0% 0%, 75% 0%, 100% 50%, 75% 100%, 0% 100%);
  clip-path: polygon(0% 0%, 75% 0%, 100% 50%, 75% 100%, 0% 100%);
}

.clipped-message-balloon {
  -webkit-clip-path: polygon(0% 0%, 100% 0%, 100% 75%, 75% 75%, 75% 100%, 50% 75%, 0% 75%);
  clip-path: polygon(0% 0%, 100% 0%, 100% 75%, 75% 75%, 75% 100%, 50% 75%, 0% 75%);
}

.clipped-octagon {
  -webkit-clip-path: polygon(30% 0%, 70% 0%, 100% 30%, 100% 70%, 70% 100%, 30% 100%, 0% 70%, 0% 30%);
  clip-path: polygon(30% 0%, 70% 0%, 100% 30%, 100% 70%, 70% 100%, 30% 100%, 0% 70%, 0% 30%);
}

.clipped-pentagon {
  -webkit-clip-path: polygon(50% 0%, 100% 38%, 82% 100%, 18% 100%, 0% 38%);
  clip-path: polygon(50% 0%, 100% 38%, 82% 100%, 18% 100%, 0% 38%);
}

.clipped-triangle {
  -webkit-clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
  clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
}

.clipped-star {
  -webkit-clip-path: polygon(50% 0%, 61% 35%, 98% 35%, 68% 57%, 79% 91%, 50% 70%, 21% 91%, 32% 57%, 2% 35%, 39% 35%);
  clip-path: polygon(50% 0%, 61% 35%, 98% 35%, 68% 57%, 79% 91%, 50% 70%, 21% 91%, 32% 57%, 2% 35%, 39% 35%);
}

.clipped-cross {
  -webkit-clip-path: polygon(10% 25%, 35% 25%, 35% 0%, 65% 0%, 65% 25%, 90% 25%, 90% 50%, 65% 50%, 65% 100%, 35% 100%, 35% 50%, 10% 50%);
  clip-path: polygon(10% 25%, 35% 25%, 35% 0%, 65% 0%, 65% 25%, 90% 25%, 90% 50%, 65% 50%, 65% 100%, 35% 100%, 35% 50%, 10% 50%);
}

.clipped-rabbet {
  -webkit-clip-path: polygon(0% 15%, 15% 15%, 15% 0%, 85% 0%, 85% 15%, 100% 15%, 100% 85%, 85% 85%, 85% 100%, 15% 100%, 15% 85%, 0% 85%);
  clip-path: polygon(0% 15%, 15% 15%, 15% 0%, 85% 0%, 85% 15%, 100% 15%, 100% 85%, 85% 85%, 85% 100%, 15% 100%, 15% 85%, 0% 85%);
}

.clipped-elipse {
  -webkit-clip-path: ellipse(25% 40% at 50% 50%);
  clip-path: ellipse(25% 40% at 50% 50%);
}