/* ============================================
   Tchoff — Professional Responsive Styles
   Breakpoints:
   - Mobile: 320px–767px
   - Tablet: 768px–1023px
   - Laptop: 1024px–1439px
   - Desktop: 1440px+
   ============================================ */

:root {
  --bg: #0a0a0b;
  --bg-card: #141416;
  --border: #252528;
  --text: #f4f4f5;
  --text-muted: #71717a;
  --accent: #22c55e;
  --accent-hover: #16a34a;
  --danger: #ef4444;
  --radius: 12px;
  --radius-sm: 8px;
  --font-sans: 'Instrument Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, monospace;
  --header-h: 56px;
  --max-content: 1200px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { font-size: 16px; }
body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

/* Header */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  min-height: var(--header-h);
  background: rgba(10, 10, 11, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
@media (min-width: 768px) { .header { padding: 16px 24px; } }
@media (min-width: 1024px) { .header { padding: 16px 32px; } }

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -0.02em;
}
@media (min-width: 768px) { .logo { font-size: 1.5rem; } }

.nav { display: flex; gap: 6px; align-items: center; }
@media (min-width: 768px) { .nav { gap: 8px; } }

.btn-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s;
}
@media (min-width: 768px) { .btn-icon { width: 44px; height: 44px; border-radius: var(--radius); } }

.btn-icon:hover {
  background: var(--bg-card);
  border-color: var(--text-muted);
}

/* Main */
.main {
  max-width: var(--max-content);
  margin: 0 auto;
  padding: 20px 16px;
}
@media (min-width: 768px) { .main { padding: 28px 24px; } }
@media (min-width: 1024px) { .main { padding: 32px 24px; } }
@media (min-width: 1440px) { .main { padding: 40px 32px; } }

/* Feed grid */
.feed-grid {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(2, 1fr);
}
@media (min-width: 640px) { .feed-grid { gap: 16px; grid-template-columns: repeat(3, 1fr); } }
@media (min-width: 1024px) { .feed-grid { grid-template-columns: repeat(4, 1fr); } }
@media (min-width: 1440px) { .feed-grid { gap: 20px; } }

.feed-grid.grid-4x4 {
  grid-template-columns: repeat(2, 1fr);
}
@media (min-width: 640px) { .feed-grid.grid-4x4 { grid-template-columns: repeat(3, 1fr); } }
@media (min-width: 1024px) { .feed-grid.grid-4x4 { grid-template-columns: repeat(4, 1fr); } }

.feed-grid:not(:empty) + .empty-state { display: none; }

.empty-state {
  text-align: center;
  padding: 48px 20px;
  color: var(--text-muted);
  font-size: 0.95rem;
  max-width: 360px;
  margin: 0 auto;
  line-height: 1.6;
}
@media (min-width: 768px) { .empty-state { padding: 80px 24px; font-size: 1rem; max-width: 400px; } }

.empty-state-icon { opacity: 0.35; color: var(--text-muted); }

.error { color: var(--danger); font-size: 0.9rem; }

/* Post card */
.post-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  cursor: pointer;
  transition: border-color 0.2s, transform 0.15s;
}
@media (min-width: 768px) { .post-card { border-radius: var(--radius); } }

.post-card:hover { border-color: var(--text-muted); transform: translateY(-2px); }

.post-image-wrap {
  aspect-ratio: 1;
  overflow: hidden;
  background: var(--border);
}

.post-image {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.post-info { padding: 12px; }
@media (min-width: 768px) { .post-info { padding: 16px; } }

.post-user, .post-user-link { font-weight: 600; font-size: 0.9rem; margin-bottom: 4px; }
@media (min-width: 768px) { .post-user, .post-user-link { font-size: 0.95rem; } }

.post-user-link { color: var(--accent); text-decoration: none; }
.post-user-link:hover { text-decoration: underline; }

.post-caption {
  font-size: 0.85rem;
  color: var(--text-muted);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
@media (min-width: 768px) { .post-caption { font-size: 0.9rem; } }

.post-stats { font-size: 0.8rem; color: var(--text-muted); margin: 6px 0 4px; }
@media (min-width: 768px) { .post-stats { font-size: 0.85rem; } }

.post-hash {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--text-muted);
  opacity: 0.7;
  margin-top: 6px;
  word-break: break-all;
}
@media (min-width: 768px) { .post-hash { font-size: 0.7rem; margin-top: 8px; } }

/* Modals */
.modal {
  border: none;
  background: transparent;
  padding: 0;
  max-width: 95vw;
}
@media (min-width: 768px) { .modal { max-width: 90vw; } }

.modal::backdrop { background: rgba(0, 0, 0, 0.85); }

.modal-content {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  width: min(100%, 380px);
  max-width: 100%;
}
@media (min-width: 768px) {
  .modal-content {
    padding: 32px;
    width: 420px;
    border-radius: 16px;
  }
}

.modal-content-full {
  width: min(95vw, 400px);
  padding: 20px;
}
@media (min-width: 768px) {
  .modal-content-full { width: min(90vw, 640px); padding: 24px; }
}

.modal h2 { font-size: 1.15rem; margin-bottom: 8px; }
@media (min-width: 768px) { .modal h2 { font-size: 1.25rem; } }

.modal-hint { font-size: 0.85rem; color: var(--text-muted); margin-bottom: 20px; }
@media (min-width: 768px) { .modal-hint { font-size: 0.875rem; margin-bottom: 24px; } }

.modal input[type="text"] {
  width: 100%;
  padding: 12px 16px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-size: 1rem;
  margin-bottom: 12px;
}

.modal input[type="text"]:focus { outline: none; border-color: var(--accent); }

.modal-actions { display: flex; gap: 10px; justify-content: flex-end; margin-top: 20px; }

/* Upload */
.upload-source-tabs { display: flex; gap: 8px; margin-bottom: 16px; }

.upload-tab {
  flex: 1;
  padding: 10px 16px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-muted);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.2s;
}

.upload-tab.active { background: var(--bg); border-color: var(--accent); color: var(--accent); }

.upload-dropzone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 32px 20px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  margin-bottom: 16px;
}
@media (min-width: 768px) { .upload-dropzone { padding: 48px 24px; } }

.upload-dropzone:hover, .upload-dropzone.dragover {
  border-color: var(--accent);
  background: rgba(34, 197, 94, 0.05);
}

.dropzone-text { color: var(--text-muted); font-size: 0.9rem; }

.camera-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 16px;
}

.camera-container video {
  width: 100%;
  max-width: 320px;
  border-radius: var(--radius);
  background: #000;
}

.hash-dropzone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 16px;
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 12px;
  cursor: pointer;
}
.hash-dropzone:hover, .hash-dropzone.dragover { border-color: var(--accent); color: var(--text); }

/* Buttons */
.btn {
  padding: 10px 18px;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: background 0.2s;
}

.btn-primary { background: var(--accent); color: var(--bg); }
.btn-primary:hover:not(:disabled) { background: var(--accent-hover); }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }

.btn-ghost { background: transparent; color: var(--text-muted); }
.btn-ghost:hover { background: var(--bg); color: var(--text); }

.btn-follow {
  padding: 8px 20px;
  background: var(--accent);
  color: var(--bg);
  border: none;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.2s;
}
.btn-follow:hover { opacity: 0.9; }
.btn-follow.following { background: transparent; color: var(--text-muted); border: 1px solid var(--border); }

.btn-close {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 36px;
  height: 36px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 50%;
  color: var(--text);
  font-size: 1.4rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  line-height: 1;
  z-index: 10;
}
@media (min-width: 768px) { .btn-close { top: 16px; right: 16px; width: 40px; height: 40px; font-size: 1.5rem; } }

.btn-close:hover { background: var(--border); }

/* Lightbox */
.modal-lightbox .modal-content { position: relative; }

.lightbox-body { display: flex; flex-direction: column; gap: 16px; }

.lightbox-image-wrap {
  aspect-ratio: 1;
  max-height: 60vh;
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--border);
}
@media (min-width: 768px) { .lightbox-image-wrap { max-height: 70vh; } }

.lightbox-image { width: 100%; height: 100%; object-fit: contain; }

.lightbox-meta { padding: 0 4px; }
@media (min-width: 768px) { .lightbox-meta { padding: 0 8px; } }

.lightbox-hash { font-family: var(--font-mono); font-size: 0.75rem; color: var(--accent); word-break: break-all; }

.lightbox-meta-extra, .post-meta-small { font-size: 0.7rem; color: var(--text-muted); margin-top: 4px; }

/* Hash result */
.hash-result {
  margin-top: 20px;
  padding: 16px;
  background: var(--bg);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.hash-result img { max-width: 100%; max-height: 300px; border-radius: var(--radius); display: block; margin: 0 auto 12px; }

.hash-result .error { color: var(--danger); }
.hash-result .success { color: var(--accent); }

.loading { text-align: center; padding: 40px; color: var(--text-muted); font-size: 0.95rem; }

/* User page */
.user-page .user-info { margin-bottom: 20px; }
@media (min-width: 768px) { .user-page .user-info { margin-bottom: 24px; } }

.user-header {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

.user-page .user-username {
  font-size: 1.35rem;
  font-weight: 600;
  margin-bottom: 0;
}
@media (min-width: 768px) { .user-page .user-username { font-size: 1.5rem; } }

.user-stats {
  display: flex;
  gap: 16px;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.user-stat-link {
  background: none;
  border: none;
  color: var(--accent);
  cursor: pointer;
  font-size: inherit;
  padding: 0;
}
.user-stat-link:hover { text-decoration: underline; }

.follow-list-item {
  display: block;
  padding: 12px 0;
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid var(--border);
}
.follow-list-item:hover { text-decoration: underline; }

/* Pagination */
.pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  margin-top: 28px;
  padding: 16px;
  flex-wrap: wrap;
}
@media (min-width: 768px) { .pagination { gap: 16px; margin-top: 32px; } }

.pagination-btn.disabled { opacity: 0.5; pointer-events: none; }

.pagination-info { color: var(--text-muted); font-size: 0.9rem; }

/* Auth */
.modal input[type="email"], .modal input[type="password"] {
  width: 100%;
  padding: 12px 16px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-size: 1rem;
  margin-bottom: 12px;
}

.modal .auth-tabs { display: flex; gap: 8px; margin-bottom: 20px; }

.modal .auth-tab {
  padding: 8px 16px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-muted);
  cursor: pointer;
  font-size: 0.9rem;
}

.modal .auth-tab.active { background: var(--bg); border-color: var(--accent); color: var(--accent); }

.modal .auth-form { display: none; }
.modal .auth-form.active { display: block; }

/* Visibility */
.visibility-wrap { margin-bottom: 12px; }
.visibility-wrap label { display: block; font-size: 0.85rem; color: var(--text-muted); margin-bottom: 6px; }
.visibility-wrap select {
  width: 100%;
  padding: 12px 16px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-size: 1rem;
}

/* Post stats in cards */
.post-stats { font-size: 0.85rem; color: var(--text-muted); margin: 6px 0 4px; }

/* Like button */
.btn-like {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-muted);
  font-size: 1rem;
  cursor: pointer;
  transition: all 0.2s;
}
.btn-like:hover { border-color: var(--accent); color: var(--accent); }
.btn-like.liked { border-color: var(--accent); color: var(--accent); }

.lightbox-actions { display: flex; align-items: center; gap: 16px; margin: 12px 0; }
.lightbox-comment-count { font-size: 0.9rem; color: var(--text-muted); }

/* Comments */
.lightbox-comments { margin-top: 16px; padding-top: 16px; border-top: 1px solid var(--border); }
.comments-list { max-height: 200px; overflow-y: auto; margin-bottom: 12px; }
.comment { font-size: 0.95rem; margin-bottom: 8px; }
.comment-user { font-weight: 600; color: var(--accent); }
.no-comments, .comment-hint { font-size: 0.9rem; color: var(--text-muted); }
.comment-form { display: flex; gap: 8px; }
.comment-form input { flex: 1; }

/* Friends */
.friends-section { margin-top: 24px; padding-top: 24px; border-top: 1px solid var(--border); }
.friends-section label { display: block; font-size: 0.85rem; color: var(--text-muted); margin-bottom: 8px; }
.add-friend-row { display: flex; gap: 8px; margin-bottom: 16px; }
.add-friend-row input { flex: 1; }
.friends-list, .pending-requests { font-size: 0.9rem; }
.friend-item { padding: 8px 0; border-bottom: 1px solid var(--border); }
.friend-item a { color: var(--accent); text-decoration: none; margin-left: 8px; }
.friend-item a:hover { text-decoration: underline; }
.friends-empty { color: var(--text-muted); font-size: 0.9rem; }