app/static/myStyles.css

body {
  background-image: url(images/background.png);
  background-size: cover;
  background-repeat: no-repeat;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100vh;
  margin: 0;
}

.brand-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-top: 13%;
  text-align: center;
}

.brand-container img {
  display: block;
  width: 130%;
  max-width: 1500px;
}

span {
  color: #f3f3f3;
  font-family: Arial, Helvetica, sans-serif;
  font-size: 30px;
  margin-top: 5%;
}

.buttons-container {
  display: flex;
  align-items: center;
  justify-content: center;
  padding-right: 0;
  margin-top: 10%;
}

label {
  cursor: pointer;
  margin: -3px;
}

input[type="file"] {
  display: none;
  margin: 0;
  padding: 0;
}

button {
  display: none;
}

label img {
  transition: transform 0.2s ease-in-out;
}

label:hover img {
  transform: scale(1.1);
}
/*loading screen*/

#loading-screen {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: url(images/background.png);
  background-size: cover;
  background-repeat: no-repeat;
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 9999;
}

.loading-spinner {
  border: 8px solid lightgray;
  border-top: 8px solid silver;
  border-radius: 50%;
  width: 50px;
  height: 50px;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}