/* Tokens. The only place colors are written; everything else uses var(). */

:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --surface: #ffffff;
  --text: #333333;
  --text-muted: #666666;
  --border: rgb(0 0 0 / 10%);
  --hover: #f0f0f0;
  --active: #e0e0e0;
  --pressed: #d0d0d0;
  --link: #007acc;
  --link-hover: #005599;
  --focus: #007acc;
  --toast-bg: rgb(64 64 64 / 95%);
  --toast-text: #f5f5f5;
  --success: #81c784;
  --error: #ef9a9a;
  --spinner-track: #f0f0f0;
  --spinner-head: #666666;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #121212;
    --surface: #1e1e1e;
    --text: #e6e6e6;
    --text-muted: #a3a3a3;
    --border: rgb(255 255 255 / 12%);
    --hover: #2a2a2a;
    --active: #333333;
    --pressed: #3d3d3d;
    --link: #4db3ff;
    --link-hover: #80c8ff;
    --focus: #4db3ff;
    --toast-bg: rgb(235 235 235 / 95%);
    --toast-text: #1f1f1f;
    --success: #2e7d32;
    --error: #c62828;
    --spinner-track: #2a2a2a;
    --spinner-head: #a3a3a3;
  }
}

/* Base */

html {
  background-color: var(--bg);
}

html,
body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  font-family:
    -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial,
    sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Stops double-tap zoom on controls; pinch zoom still works everywhere */
a,
button {
  touch-action: manipulation;
}

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

/* Layout */

.page {
  display: flex;
  flex-direction: column;
  max-width: 1024px;
  height: 100vh;
  height: 100dvh;
  margin-inline: auto;
}

.header {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: center;
  min-height: 44px; /* iOS touch target size */
  padding: max(15px, env(safe-area-inset-top))
    max(10px, env(safe-area-inset-right)) 15px
    max(10px, env(safe-area-inset-left));
  text-align: center;
  background-color: var(--surface);
  border-bottom: 1px solid var(--border);
}

.header h1 {
  margin: 0;
  color: var(--text);
  font-size: 20px;
  font-weight: 600;
}

.header-title {
  color: inherit;
  text-decoration: none;
  transition: opacity 0.2s ease;
  -webkit-tap-highlight-color: transparent;
}

.header-title:hover {
  opacity: 0.8;
}

.header-title:active {
  opacity: 0.6;
}

/* Zero height, so the buttons overflow the row instead of making the header taller */
.nav-arrows-left,
.header-controls {
  display: flex;
  align-items: center;
  gap: 8px;
  height: 0;
}

.nav-arrows-left {
  justify-self: start;
}

.header-controls {
  justify-self: end;
}

.footer {
  padding: 10px max(20px, env(safe-area-inset-right))
    max(15px, env(safe-area-inset-bottom)) max(20px, env(safe-area-inset-left));
  text-align: center;
  font-size: 13px;
  color: var(--text-muted);
  background-color: var(--surface);
}

.footer a {
  margin: 0 4px;
  color: var(--link);
  text-decoration: none;
  transition: color 0.2s ease;
}

.footer a:hover {
  color: var(--link-hover);
  text-decoration: underline;
}

/* Components */

.icon-button {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border: none;
  border-radius: 50%;
  background: none;
  color: var(--text-muted);
  text-decoration: none;
  cursor: pointer;
  transition:
    background-color 0.2s ease,
    color 0.2s ease;
  -webkit-tap-highlight-color: transparent;
}

.icon-button:hover {
  background-color: var(--hover);
  color: var(--text);
}

.icon-button:active {
  background-color: var(--active);
  transform: scale(0.95);
}

.notifications-button {
  position: relative;
  font-size: 18px; /* Sets the icon spans' line height, which centers the icons */
}

.notifications-button .notifications-on,
.notifications-button .notifications-off {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  transition: opacity 0.2s ease;
}

.user-profile {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 12px max(15px, env(safe-area-inset-right)) 12px
    max(15px, env(safe-area-inset-left));
  background-color: var(--surface);
}

.user-row {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.user-summary {
  display: flex;
  align-items: center;
  gap: 12px;
}

.user-profile img {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  object-fit: cover;
}

.user-info {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.user-name {
  margin: 0;
  font-size: 15px;
  font-weight: 600;
  line-height: 1.2;
  color: var(--text);
}

.user-username {
  margin: 0;
  font-size: 13px;
  line-height: 1.2;
  color: var(--text-muted);
  text-decoration: none;
  -webkit-tap-highlight-color: transparent;
}

.user-username:hover {
  color: var(--text);
  text-decoration: underline;
}

.right-section {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 4px;
}

.likes-count {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 16px;
  line-height: 1.2;
  color: var(--text-muted);
}

.likes-count svg {
  width: 18px;
  height: 18px;
  vertical-align: middle;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}

.tag {
  padding: 3px 6px;
  border-radius: 10px;
  font-size: 11px;
  line-height: 1.2;
  white-space: nowrap;
  color: var(--text-muted);
  text-decoration: none;
  background-color: var(--hover);
  -webkit-tap-highlight-color: transparent;
}

.tag:hover {
  background-color: var(--active);
  color: var(--text);
}

.tag:active {
  background-color: var(--pressed);
  transform: scale(0.95);
}

.photo-container {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding-inline: env(safe-area-inset-left) env(safe-area-inset-right);
  overflow: hidden;
  container-type: size;
}

.photo-container a {
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 5px;
  -webkit-tap-highlight-color: transparent;
}

.cat-image {
  max-width: 100%;
  /* The link's height is auto, so 100% would not limit tall photos. */
  max-height: 100cqh;
  margin: 0 8px;
  object-fit: contain;
  border-radius: 8px;
  -webkit-user-select: none;
  user-select: none;
}

.toast {
  position: fixed;
  top: max(70px, calc(env(safe-area-inset-top) + 15px));
  left: 50%;
  z-index: 1000;
  max-width: 85%;
  padding: 10px 16px;
  border-radius: 8px;
  font-size: 13px;
  text-align: center;
  color: var(--toast-text);
  background-color: var(--toast-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  opacity: 0;
  visibility: hidden;
  transform: translate(-50%, -8px);
  transition:
    opacity 0.3s ease,
    transform 0.3s ease,
    visibility 0.3s ease;
}

.toast.show {
  opacity: 1;
  visibility: visible;
  transform: translate(-50%, 0);
}

.toast.success {
  border-left: 4px solid var(--success);
}

.toast.error {
  border-left: 4px solid var(--error);
}

.loading-container {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  padding: 30px 15px;
}

.loading-spinner {
  position: relative;
  width: 50px;
  height: 50px;
}

.spinner {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 4px solid var(--spinner-track);
  border-top-color: var(--spinner-head);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.loading-text {
  font-size: 15px;
  line-height: 1.4;
  text-align: center;
  color: var(--text-muted);
}

.not-found {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 30px 15px;
  text-align: center;
}

.not-found img {
  width: 96px;
  height: 96px;
}

.not-found h2 {
  margin: 0;
  font-size: 20px;
  font-weight: 600;
  color: var(--text);
}

.not-found p {
  margin: 0;
  font-size: 15px;
  line-height: 1.4;
  color: var(--text-muted);
}

.not-found-link {
  margin-top: 8px;
  padding: 10px 18px;
  border-radius: 20px;
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  text-decoration: none;
  background-color: var(--hover);
  transition: background-color 0.2s ease;
  -webkit-tap-highlight-color: transparent;
}

.not-found-link:hover {
  background-color: var(--active);
}

.not-found-link:active {
  background-color: var(--pressed);
  transform: scale(0.95);
}

/* Larger screens */

@media (min-width: 1025px) {
  .header {
    min-height: auto;
    padding: max(20px, env(safe-area-inset-top))
      max(20px, env(safe-area-inset-right)) 20px
      max(20px, env(safe-area-inset-left));
  }

  .header h1 {
    font-size: 24px;
  }

  .footer {
    font-size: 14px;
  }

  .icon-button {
    width: 44px;
    height: 44px;
  }

  .notifications-button {
    font-size: 20px;
  }

  .user-profile {
    padding: 15px max(20px, env(safe-area-inset-right)) 15px
      max(20px, env(safe-area-inset-left));
  }

  .user-row {
    flex-direction: row;
    align-items: flex-start;
    justify-content: space-between;
  }

  .user-profile img {
    width: 40px;
    height: 40px;
  }

  .user-name {
    font-size: 16px;
  }

  .user-username {
    font-size: 14px;
  }

  .right-section {
    align-items: flex-end;
  }

  .likes-count svg {
    width: 20px;
    height: 20px;
  }

  .tags {
    gap: 6px;
  }

  .tag {
    padding: 4px 8px;
    border-radius: 12px;
    font-size: 12px;
  }

  .cat-image {
    margin: 0;
  }

  .toast {
    top: max(80px, calc(env(safe-area-inset-top) + 20px));
    max-width: 90%;
    padding: 12px 20px;
    font-size: 14px;
  }

  .loading-container {
    gap: 20px;
    padding: 40px 20px;
  }

  .loading-spinner {
    width: 60px;
    height: 60px;
  }

  .loading-text {
    font-size: 16px;
  }
}

/* Reduced motion. The spinner keeps turning: it is the only sign the page is working. */

@media (prefers-reduced-motion: reduce) {
  .header-title,
  .footer a,
  .icon-button,
  .notifications-button .notifications-on,
  .notifications-button .notifications-off,
  .tag,
  .not-found-link,
  .toast {
    transition: none;
  }

  .icon-button:active,
  .tag:active,
  .not-found-link:active {
    transform: none;
  }

  .toast {
    transform: translate(-50%, 0);
  }
}

/* Utilities. Last, so they win over component display values. */

.hidden {
  display: none;
}