CSS -

Shapes

Here are some basic CSS shapes.

Triangles

.triangle-up {
    width: 0;
    height: 0;
    border-left: 50px solid transparent;
    border-right: 50px solid transparent;
    border-bottom: 100px solid red;
}

.triangle-right {
    width: 0;
    height: 0;
    border-top: 50px solid transparent;
    border-left: 100px solid red;
    border-bottom: 50px solid transparent;
}

.triangle-topleft {
    width: 0;
    height: 0;
    border-top: 100px solid red;
    border-right: 100px solid transparent;
}

.triangle-bottomleft {
    width: 0;
    height: 0;
    border-bottom: 100px solid red;
    border-right: 100px solid transparent;
}

Other basic

.trapezoid {
    border-bottom: 100px solid red;
    border-left: 50px solid transparent;
    border-right: 50px solid transparent;
    height: 0;
    width: 100px;
}

.parallelogram {
    width: 150px;
    height: 100px;
    -webkit-transform: skew(20deg);
    -moz-transform: skew(20deg);
    -o-transform: skew(20deg);
    background: red;
}

.pentagon {
    position: relative;
    width: 54px;
    border-width: 50px 18px 0;
    border-style: solid;
    border-color: red transparent;
}
.pentagon:before {
    content: '';
    position: absolute;
    height: 0;
    width: 0;
    top: -85px;
    left: -18px;
    border-width: 0 45px 35px;
    border-style: solid;
    border-color: transparent transparent red;
}

.octagon {
    width: 100px;
    height: 100px;
    background: red;
    position: relative;
}
.octagon:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    border-bottom: 29px solid red;
    border-left: 29px solid white;
    border-right: 29px solid white;
    width: 42px;
    height: 0;
}
.octagon:after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    border-top: 29px solid red;
    border-left: 29px solid white;
    border-right: 29px solid white;
    width: 42px;
    height: 0;
}

Symbols

.diamond {
    width: 0;
    height: 0;
    border: 50px solid transparent;
    border-bottom-color: red;
    position: relative;
    top: -50px;
}
.diamond:after {
    content: '';
    position: absolute;
    left: -50px;
    top: 50px;
    width: 0;
    height: 0;
    border: 50px solid transparent;
    border-top-color: red;
}

.cut-diamond {
    border-style: solid;
    border-color: transparent transparent red transparent;
    border-width: 0 25px 25px 25px;
    height: 0;
    width: 50px;
    position: relative;
    margin: 20px 0 50px 0;
}
.cut-diamond:after {
    content: '';
    position: absolute;
    top: 25px;
    left: -25px;
    width: 0;
    height: 0;
    border-style: solid;
    border-color: red transparent transparent transparent;
    border-width: 70px 50px 0 50px;
}

.heart {
    position: relative;
    width: 100px;
    height: 90px;
}
.heart:before,
.heart:after {
    position: absolute;
    content: '';
    left: 50px;
    top: 0;
    width: 50px;
    height: 80px;
    background: red;
    -moz-border-radius: 50px 50px 0 0;
    border-radius: 50px 50px 0 0;
    -webkit-transform: rotate(-45deg);
    -moz-transform: rotate(-45deg);
    -ms-transform: rotate(-45deg);
    -o-transform: rotate(-45deg);
    transform: rotate(-45deg);
    -webkit-transform-origin: 0 100%;
    -moz-transform-origin: 0 100%;
    -ms-transform-origin: 0 100%;
    -o-transform-origin: 0 100%;
    transform-origin: 0 100%;
}
.heart:after {
    left: 0;
    -webkit-transform: rotate(45deg);
    -moz-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    transform: rotate(45deg);
    -webkit-transform-origin: 100% 100%;
    -moz-transform-origin: 100% 100%;
    -ms-transform-origin: 100% 100%;
    -o-transform-origin: 100% 100%;
    transform-origin :100% 100%;
}

Badges

.burst-8 {
    background: red;
    width: 80px;
    height: 80px;
    position: relative;
    text-align: center;
    -webkit-transform: rotate(20deg);
    -moz-transform: rotate(20deg);
    -ms-transform: rotate(20deg);
    -o-transform: rotate(20eg);
}
.burst-8:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    height: 80px;
    width: 80px;
    background: red;
    -webkit-transform: rotate(135deg);
    -moz-transform: rotate(135deg);
    -ms-transform: rotate(135deg);
    -o-transform: rotate(135deg);
}

.burst-12 {
    background: red;
    width: 80px;
    height: 80px;
    position: relative;
    text-align: center;
}
.burst-12:before,
.burst-12:after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    height: 80px;
    width: 80px;
    background: red;
}
.burst-12:before {
    -webkit-transform: rotate(30deg);
    -moz-transform: rotate(30deg);
    -ms-transform: rotate(30deg);
    -o-transform: rotate(30deg);
}
.burst-12:after {
    -webkit-transform: rotate(60deg);
    -moz-transform: rotate(60deg);
    -ms-transform: rotate(60deg);
    -o-transform: rotate(60deg);
}