:root {
  /* Primary / Accent */
  --primary: #FACC15;

  /* Surfaces / Background */
  --surface: #000000;
  --background: #000000;

  /* Text shades */
  --text-primary: #f5f5f5;
  --text-secondary: #9ca3af;

  /* Search field */
  --search-background: #111111;
  --search-selected: #111111;

  /* Elevation shadows (dark-theme) */
  --elevation-low: 0 1px 3px rgba(255, 255, 255, 0.3),
    0 1px 1px rgba(255, 255, 255, 0.24);
  --elevation-medium: 0 1px 3px rgba(255, 255, 255, 0.4),
    0 1px 3px rgba(255, 255, 255, 0.24);
}

html {
  font-size: 10px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  background-color: var(--background);
  color: var(--text-primary);
  font-family: 'Roboto', sans-serif;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

/* header */
.gallery-header {
  position: sticky;
  top: 0;
  background-color: var(--surface);
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1rem 0 0.5rem;
  box-shadow: var(--elevation-low);
  z-index: 10;
}

.gallery-header h1 {
  margin: 0;
  font-size: 2rem;
  font-weight: 500;
  color: var(--primary);
}

.filter-container {
  margin-top: 1rem;
}

#search-input {
  width: 80%;
  max-width: 400px;
  padding: 0.8rem 1.2rem;
  font-size: 1.2rem;
  font-weight: 400;
  border: none;
  border-radius: 4px;
  background-color: var(--search-background);
  color: var(--text-primary);
  box-shadow: var(--elevation-low);
  transition: box-shadow 0.2s ease, background-color 0.2s ease;
}

#search-input::placeholder {
  color: var(--text-secondary);
}

#search-input:focus {
  outline: none;
  box-shadow: var(--elevation-medium);
  background-color: var(--search-selected);
}

/* gallery */
main#gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  grid-auto-rows: 150px;
  grid-auto-flow: dense;
  gap: 16px;
  padding: 24px;
  max-width: 1280px;
  margin: 0 auto;
}

.photo-item {
  position: relative;
  overflow: hidden;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

/* elevated card */
.photo-card {
  background-color: var(--surface);
  border-radius: 4px;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  width: 100%;
  height: 100%;
}

.photo-card:hover {
  transform: translateY(-4px);
}

.photo-card img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  cursor: pointer;
  transition: transform 0.2s ease;
}

.photo-card:hover img {
  transform: scale(1.02);
}

/* mosaics */
.photo-item.span2x2 {
  grid-column: span 2;
  grid-row: span 2;
}

.photo-item.span2x1 {
  grid-column: span 2;
}

.photo-item.span1x2 {
  grid-row: span 2;
}

/* captions */
.photo-info {
  margin-top: 8px;
  padding: 0 8px 8px;
  text-align: center;
}

.photo-info h3 {
  margin: 0 0 4px;
  font-size: 1.4rem;
  font-weight: 500;
  color: var(--text-primary);
}

.photo-info p {
  margin: 0;
  font-size: 1.2rem;
  font-weight: 300;
  color: var(--text-secondary);
  line-height: 1.4;
}

/* lightbox */
.lightbox {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.88);
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  z-index: 1000;
}

.lightbox.hidden {
  display: none;
}

.lightbox-close {
  position: absolute;
  top: 1.5rem;
  right: 1.5rem;
  font-size: 3.2rem;
  color: var(--text-primary);
  cursor: pointer;
  transition: color 0.2s ease;
}

.lightbox-close:hover {
  color: var(--primary);
}

.lightbox-img {
  max-width: 90%;
  max-height: 80%;
  border-radius: 4px;
  margin-bottom: 1rem;
}

.lightbox-caption {
  font-size: 1.6rem;
  color: var(--text-primary);
  text-align: center;
  max-width: 90%;
  padding: 0 1rem;
}

/* stuff */
@media (max-width: 1024px) {
  main#gallery {
    column-count: 3;
  }
}

@media (max-width: 768px) {
  main#gallery {
    column-count: 2;
  }
}

@media (max-width: 600px) {
  .gallery-header h1 {
    font-size: 2rem;
  }
  main#gallery {
    column-count: 1;
    padding: 16px;
    column-gap: 16px;
  }
  #search-input {
    width: 90%;
  }
}