static/style.css

body {
  --text: hsl(0 0% 15%);
  padding: 2.5rem;
  font-family: sans-serif;
  color: var(--text);
}

body.dark-theme {
  --text: hsl(0 0% 90%);
  background-color: hsl(223 39% 7%);
}

main {
  max-width: 80rem;
  text-align: left;
}

section {
  display: flex;
  flex-direction: column;
  align-items: center;
}

a {
  color: var(--text);
}

form {
  width: 700px;
  margin: 0 auto;
}


button {
  cursor: pointer;
  align-items: center;
}

/*  */
/* Popup container */
.popup {
  position: relative;
  display: inline-block;
  cursor: pointer;
}

/* The actual popup (appears on top) */
.popup .popuptext {
  visibility: hidden;
  width: 160px;
  background-color: #555;
  color: #fff;
  text-align: center;
  border-radius: 6px;
  padding: 8px 0;
  position: absolute;
  z-index: 1;
  bottom: 125%;
  left: 50%;
  margin-left: -80px;
}

/* Popup arrow */
.popup .popuptext::after {
  content: "";
  position: absolute;
  top: 100%;
  left: 50%;
  margin-left: -5px;
  border-width: 5px;
  border-style: solid;
  border-color: #555 transparent transparent transparent;
}

/* Toggle this class when clicking on the popup container (hide and show the popup) */
.popup .show {
  visibility: visible;
  -webkit-animation: fadeIn 1s;
  animation: fadeIn 1s
}

/* The Modal (background) */
.modal {
  display: none; /* Hidden by default */
  position: fixed; /* Stay in place */
  z-index: 1; /* Sit on top */
  left: 0;
  top: 0;
  width: 100%; /* Full width */
  height: 100%; /* Full height */
  overflow: auto; /* Enable scroll if needed */
  background-color: rgb(0,0,0); /* Fallback color */
  background-color: rgba(0,0,0,0.4); /* Black w/ opacity */
}

/* Modal Content/Box */
.modal-content {
  background-color: #fefefe;
  margin: 15% auto; /* 15% from the top and centered */
  padding: 20px;
  border: 1px solid #888;
  width: 80%; /* Could be more or less, depending on screen size */
}

/* The Close Button */
.close {
  color: #aaa;
  float: right;
  font-size: 28px;
  font-weight: bold;
}

.close:hover,
.close:focus {
  color: black;
  text-decoration: none;
  cursor: pointer;
}