:root {
  --primary-color: #252839;
  --secondary-color: #2b2e3f;
  --border-color: #4b4e5f;
  --text-color2: #f6f6f6;
}
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
body {
  background-color: var(--primary-color);
}

/* Projects */
#projects-container {
  display: grid;
  grid-template-columns: 1fr;
  justify-items: center;
  gap: 1rem;
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 1rem 50px 1rem;
}
.project-tile {
  position: relative;
  aspect-ratio: 16 / 9;
  width: 100%;
  max-width: 400px;
  border: 2px solid var(--border-color);
  border-radius: 8px;
  overflow: hidden;
  background-color: var(--secondary-color);
}
.project-image {
  position: absolute;
  inset: 0;
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center top;
}
.project-tile:nth-of-type(3) .project-image {
  object-position: left top;
}

/* Scroll-to-top */
#back-to-top {
  z-index: 999;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s ease, visibility 0.3s ease;
}
#back-to-top.show {
  opacity: 1;
  visibility: visible;
}
#arrow-circle {
  border-radius: 50%;
  font-size: clamp(2.8rem, 5vw, 3rem);
  color: var(--text-color2);
  background-color: var(--primary-color);
  opacity: 0.75;
}
#arrow-circle:hover {
  opacity: 1;
  transition: opacity 0.2s ease-in-out;
}

/* Responsiveness */
@media (min-width: 768px) {
  #projects-container {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    justify-items: stretch;
    padding: 50px 2rem;
  }
  .project-tile {
    width: 100%;
    max-width: unset;
  }
}