style.css

body {
    font-family: 'Montserrat', sans-serif;
    height: 100%;
    width: 100%;
    margin: 0;
    padding: 0;
    min-width: 400px;
}

header {
    height: 100px;
    width: 100%;
    background: -webkit-linear-gradient(left, #D2EBF0, #1CD3DD);
    background: linear-gradient(left, #D2EBF0, #1CD3DD);
    display: flex;
    align-items: center;
}

h1 {
    font-size: 2.5em;
    margin: 2em;
    font-style: italic;
}

.header_desc {
    font-size: 1em;
    margin-left: 2em;
}
.slider_wrapper {
  width: 100%;
  height: 65vh;
  position: relative;
  border: none;
  box-sizing: border-box;
  margin: 0 auto;
  padding: 0;
  display: flex;
  align-items: center;
  overflow: hidden;
}
img[name = "slider_item"] {
  position: relative;
  border: none;
  min-width: 100%;
  height: 100%;
  transition: 0.2s;
}
img {
  object-fit: hover;
}

/* popup */

.popup {
  width: 50%;
  height: 50vh;
  background: -webkit-linear-gradient(left, #D2EBF0, #1CD3DD);
  position: fixed;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  transition: 200ms ease-in-out;
  border: 1px solid black;
  z-index: 1;
  display: none;
}
.popup-content {
  display: flex;
}

#popup-btn {
  position: relative;
  left: 50%;
  transform: translate(-50%, 0);
  font-size: 30px;
  font-style: italic;
  margin-top: 3vh;
  margin-bottom: 3vh;
}
h2 {
  padding: 10px 15px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.close {
  cursor: pointer;
  font-size: 24px;
  margin-left: auto;
  font-weight: bold;
}
.popup-body p {
  font-size: 1.5rem;
  text-align: center;
}
footer {
  position: absolute;
  width: 100%;
  bottom: 0;
  height: 65px;
  background: #1CD3DD;
}
.footer_text {
  margin-left: 15%;
}