body {
  display: -ms-flexbox;
  display: flex;
  -ms-flex-align: center;
  align-items: center;
  flex-wrap: wrap;
}

main {
  width: 100% !important;
}

.form-signin {
  max-width: 400px;
  width: 100%;
  padding: 15px;
  margin: auto;
  background-color: rgba(255,255,255,0.7);
  border-radius: .25rem;
  border: 1px solid rgba(0,0,0,.125);
}

.form-signin .form-control {
  position: relative;
  box-sizing: border-box;
  height: auto;
  padding: 10px;
  font-size: 16px;
}

.form-signin .form-control:focus {
  z-index: 2;
}
.form-signin-top {
  margin-bottom: -1px;
  border-bottom-right-radius: 0;
  border-bottom-left-radius: 0;
}

.form-signin-bottom {
  margin-bottom: 10px;
  border-top-left-radius: 0;
  border-top-right-radius: 0;

}

#captchaImage {
  width: 100%;
  max-height: 180px;
  border-top-left-radius: 4px;
  border-top-right-radius: 4px;
}

button.btn:nth-last-child(2) {
 border-radius: 0;
}
button.btn:nth-last-child(1) {
 border-top-left-radius: 0;
 border-bottom-left-radius: 0;
 border-top-right-radius: 0;
}