updating to 4.0

New design with breaking changes, gulp 4, all dependencies updated, dev environment changed, and many more changes

scss/_login.scss

@@ -0,0 +1,69 @@
+:root {
+  --input-padding-x: 0.75rem;
+  --input-padding-y: 0.75rem;
+}
+
+.card-login {
+  max-width: 25rem;
+}
+
+.card-register {
+  max-width: 40rem;
+}
+
+.form-label-group {
+  position: relative;
+}
+
+.form-label-group > input,
+.form-label-group > label {
+  padding: var(--input-padding-y) var(--input-padding-x);
+  height: auto;
+}
+
+.form-label-group > label {
+  position: absolute;
+  top: 0;
+  left: 0;
+  display: block;
+  width: 100%;
+  margin-bottom: 0;
+  /* Override default `<label>` margin */
+  line-height: 1.5;
+  color: #495057;
+  border: 1px solid transparent;
+  border-radius: 0.25rem;
+  transition: all 0.1s ease-in-out;
+}
+
+.form-label-group input::-webkit-input-placeholder {
+  color: transparent;
+}
+
+.form-label-group input:-ms-input-placeholder {
+  color: transparent;
+}
+
+.form-label-group input::-ms-input-placeholder {
+  color: transparent;
+}
+
+.form-label-group input::-moz-placeholder {
+  color: transparent;
+}
+
+.form-label-group input::placeholder {
+  color: transparent;
+}
+
+.form-label-group input:not(:placeholder-shown) {
+  padding-top: calc(var(--input-padding-y) + var(--input-padding-y) * (2 / 3));
+  padding-bottom: calc(var(--input-padding-y) / 3);
+}
+
+.form-label-group input:not(:placeholder-shown) ~ label {
+  padding-top: calc(var(--input-padding-y) / 3);
+  padding-bottom: calc(var(--input-padding-y) / 3);
+  font-size: 12px;
+  color: #777;
+}