style.css

/* popup */
.popup_wrapper {
    display: flex;
    flex: 1;
    flex-direction: column;
    width: 200px;
}

.popup_wrapper .popup_wrapper_header {
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
}

.popup_wrapper_content {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
}

.extension_ready {
    display: none;
}

.btn {
    position: relative;
    display: block;
    margin: 15px auto;
    padding: 0;
    overflow: hidden;
    border-width: 0;
    outline: none;
    border-radius: 2px;
    box-shadow: 0 1px 4px rgba(0, 0, 0, .6);
    background-color: #3498db;
    color: #ecf0f1;
    transition: background-color .3s;
}

.btn:hover, .btn:focus {
    background-color:dodgerblue;
}
  
.btn > * {
  position: relative;
}

.btn span {
  display: block;
  padding: 8px 24px;
  font-weight: bold;
  font-size: small;
}

.btn:before {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  display: block;
  width: 0;
  padding-top: 0;
  border-radius: 100%;
  background-color: rgba(236, 240, 241, .3);
  -webkit-transform: translate(-50%, -50%);
  -moz-transform: translate(-50%, -50%);
  -ms-transform: translate(-50%, -50%);
  -o-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
}

.btn:active:before {
  width: 120%;
  padding-top: 120%;
  transition: width .2s ease-out, padding-top .2s ease-out;
}

.warn,
.warn::before,
.warn::after
{
  position: relative;
  padding: 0;
  margin: 0;
}

.warn {
  font-size: 36px;
  color: transparent;
}

.warn.warning {
  display: inline-block;
  top: 0.225em;
  width: 1.15em;
  height: 1.15em;
  overflow: hidden;
  border: none;
  background-color: transparent;
  border-radius: 0.625em;
}

.warn.warning::before {
  content: "";
  display: block;
  top: -0.08em;
  left: 0.0em;
  position: absolute;
  border: transparent 0.6em solid;
  border-bottom-color: #fd3;
  border-bottom-width: 1em;
  border-top-width: 0;
  box-shadow: #999 0 1px 1px;
}

.warn.warning::after {
  display: block;
  position: absolute;
  top: 0.15em;
  left: 0;
  width: 100%;
  padding: 0 1px;
  text-align: center;
  font-family: "Garamond";
  content: "!";
  font-size: 0.65em;
  font-weight: bold;
  color: #333;
}

.tick-mark {
    position: relative;
    display: inline-block;
    width: 30px;
    height: 30px;
}

.tick-mark::before {
    position: absolute;
    left: 0;
    top: 50%;
    height: 50%;
    width: 3px;
    background-color: greenyellow;
    content: "";
    transform: translateX(10px) rotate(-45deg);
    transform-origin: left bottom;
}

.tick-mark::after {
    position: absolute;
    left: 0;
    bottom: 0;
    height: 3px;
    width: 100%;
    background-color: greenyellow;
    content: "";
    transform: translateX(10px) rotate(-45deg);
    transform-origin: left bottom;
}

/* 
*  GoSFU and MySchedule
*/
/* for Myschedule and GoSfu */
.rmp_instructor_wrapper {
    position: relative;
    margin: auto; 
    font-weight: bold;      /* font weight of instructor's name */
    text-decoration: underline;
    color: #3498db;          /* color of instructor's name */
}

.rmp_instructor_wrapper:hover{
    background-color: yellow;   /* highlight colour of instructor name when hover */
}

/* shows hover box */
.rmp_instructor_wrapper:hover .rating_box_wrapper {
    visibility: visible;
    opacity: 1;
    transform: none;
    transition-duration: 0.1s, 0.4s;    /* speed of transition */
}

/* hover box properties */
.rating_box_wrapper {
    display: flex;
    flex-direction: row;
    justify-content: center;
    align-items: center;
    min-width: 150px;
    position: absolute;
    text-align: left;
    color: black;
    visibility: hidden;    
    padding: 10px;
    background: #EEEEEE;          /* background colour of the hover box */
    border-radius: 12px;            /* border radius */
    border: #808080 solid 3px;    /* border colour and thickness */
    z-index: 999;                     /* to be in front of the schedule in myschedule */
    left: -160px;                   /* position of hover box */
    top: -155px;
    transition: opacity 0.25s ease-out, transform 0.25s ease-out;    /* first number: how fast it appears, 
                                                                        second number: how fast it moves diagonally 
                                                                        same number recommended */
    opacity: 0;
    transform: scale(0.95) translateY(1em) translateX(1em);          /* first number: how big the hoverbox starts 
                                                                        second and third number: how far it moves left and up */
}

/* hover box tail properties */
.rating_box_wrapper:after {
    content: '';
    position: absolute;
    border-style: solid;
    border-width: 10px 10px 0;                  /* tail of the hover box 
                                                   first number: length, second number width */
    border-color: #EEEEEE transparent;        /* same colour as the background */
    display: block;
    width: 0;
    z-index: 3;
    bottom: -10px;            /* position of the tail */
    left: 155px;
    
}

/* hover box tail border properties */
.rating_box_wrapper:before {
    content: '';
    position: absolute;
    border-style: solid;
    border-width: 12px 12px 0;        /* tail border (border-with of tail) + (border +- 1) */
    border-color: #808080 transparent;
    display: block;
    width: 0;
    z-index: 2;
    bottom: -15px;            /* has to have a right porportion with position of the tail */
    left: 153px;
}

.rating_item_wrapper {
    display: flex;
    flex-direction: column;
    margin: 0px 10px;
}

.rating_item_wrapper h3 {
    text-decoration: underline;
    text-align: center;
    margin-bottom: 5px;
    overflow: hidden;
}

.rating_item_wrapper p {
    margin: 1px 0px;
    font-weight: lighter;
}

.rating_item_wrapper b {
    font-weight: bolder;
    font-size: medium;
}

.rating_item_wrapper hr {
    margin: 3px 0px;
}

/* Loading Screen */
#logo {
    width: 300px;
    height: 300px;
}

.loading_wrapper {
    display: flex;
    flex: 1;
    flex-direction: column;
    justify-content: center;
    text-align: center;
    align-items: center;
    margin-top: 120px;
}

.loading_warning_header {
    padding: 20px 0px 0px 0px;
}

.loading_header {
    padding: 10px 0px 0px 0px;
}

#spinner {
    margin: 0 auto;
    border-radius: 50%;
    border: 5px solid rgba(0, 0, 0, 0.1);
    border-top-color: #3498db;
    width: 75px;
    height: 75px;
    animation: spin 1s linear infinite;
}
  @keyframes spin {
    to {
      transform: rotate(360deg);
    }
}