/* Reset & Base */
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Segoe UI", Tahoma, Arial, sans-serif;
  color: #172033;
  background-color: #eff6ff;
  line-height: 1.55;
}
a { color: #1d4ed8; text-decoration: none; }

/* 1. Header */
header.social-header {
  background: #1d4ed8;
  color: #ffffff;
  padding: 16px 24px;
}
.social-topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  max-width: 1280px;
  margin: 0 auto;
}
.social-brand h1 { margin: 0; font-size: 24px; }
.social-brand p { margin: 2px 0 0; font-size: 13px; color: #dbeafe; }
.user-avatar { font-weight: 600; font-size: 13.5px; margin-right: 8px; }
.online-indicator {
  display: inline-block;
  background: #22c55e;
  color: #ffffff;
  font-size: 11px;
  font-weight: 700;
  padding: 3px 9px;
  border-radius: 999px;
}

/* 2. Nav Flexbox */
nav.social-nav {
  background: #1e40af;
  padding: 0 20px;
}
ul.nav-social-tabs {
  display: flex;
  justify-content: space-around;
  align-items: center;
  flex-wrap: wrap;
  list-style: none;
  margin: 0;
  padding: 10px 0;
}
ul.nav-social-tabs li a {
  color: #ffffff;
  font-weight: 600;
  font-size: 14px;
  padding: 6px 12px;
  border-radius: 4px;
}
ul.nav-social-tabs li a:hover {
  background: #1d4ed8;
}

/* 3. Main 3 cột Flexbox */
main.social-main-layout {
  padding: 24px;
  max-width: 1280px;
  margin: 0 auto;
}
.social-three-columns {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 20px;
  flex-wrap: wrap;
}
.col-left-shortcuts {
  flex: 1 1 200px;
  background: #ffffff;
  border: 1px solid #bfdbfe;
  border-radius: 8px;
  padding: 16px;
}
.col-left-shortcuts h3 { margin: 0 0 12px; font-size: 15px; color: #1e40af; }
.shortcut-list { list-style: none; margin: 0; padding: 0; }
.shortcut-list li { padding: 8px 0; font-size: 13px; border-bottom: 1px dashed #e2e8f0; color: #334155; }
.shortcut-list li:last-child { border-bottom: none; }

.col-feed-center {
  flex: 3.2 1 600px;
}
.composer-card {
  background: #ffffff;
  border: 1px solid #bfdbfe;
  border-left: 5px solid #1d4ed8;
  border-radius: 8px;
  padding: 18px 20px;
  margin-bottom: 18px;
}
.composer-tag {
  display: inline-block;
  background: #dbeafe;
  color: #1d4ed8;
  font-size: 11px;
  font-weight: 700;
  padding: 2px 7px;
  border-radius: 4px;
  margin-bottom: 6px;
}
.composer-card h2 { margin: 0 0 6px; font-size: 18px; color: #0f172a; }
.composer-hint { margin: 0; font-size: 13px; color: #475569; }

/* 6 Thẻ bài viết Feed Flexbox không đều nhau */
.posts-flex-group {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-start;
  align-items: stretch;
  gap: 14px;
}
.feed-card {
  background: #ffffff;
  border: 1px solid #bfdbfe;
  border-radius: 8px;
  padding: 14px 16px;
  box-shadow: 0 1px 3px rgba(29, 78, 216, 0.05);
}
.feed-card.c1 { flex: 2.7 1 330px; }
.feed-card.c2 { flex: 1 1 160px; }
.feed-card.c3 { flex: 1.4 1 200px; align-self: flex-start; }
.feed-card.c4 { flex: 2 1 250px; }
.feed-card.c5 { flex: 1.1 1 170px; }
.feed-card.c6.pinned-announcement {
  flex: 2.5 1 310px;
  order: -1;
  background: #f0fdf4;
  border-color: #86efac;
}
.card-author {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
}
.author-name { font-weight: 700; font-size: 13.5px; color: #1e40af; }
.card-author time { font-size: 12px; color: #94a3b8; }
.feed-card p { margin: 0 0 10px; font-size: 13px; color: #334155; }
.card-stats { font-size: 12px; color: #64748b; }
.card-stats span { margin-right: 12px; }

/* Display none */
.draft-composer-state { display: none; }

.col-online-buddies {
  flex: 1 1 200px;
  background: #ffffff;
  border: 1px solid #bfdbfe;
  border-radius: 8px;
  padding: 16px;
  align-self: flex-start;
}
.col-online-buddies h3 { margin: 0 0 12px; font-size: 15px; color: #1e40af; }
.online-user-list { list-style: none; margin: 0; padding: 0; }
.online-user-list li { padding: 8px 0; font-size: 13px; border-bottom: 1px dashed #e2e8f0; color: #334155; }
.online-user-list li:last-child { border-bottom: none; }

/* 4. Footer 3 cột */
footer.social-footer {
  background: #172554;
  color: #dbeafe;
  padding: 28px 24px;
  margin-top: 36px;
}
.social-footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 20px;
  max-width: 1280px;
  margin: 0 auto;
}
.social-col { flex: 1 1 220px; }
.social-col h4 { margin: 0 0 10px; font-size: 15px; color: #ffffff; }
.social-col p { margin: 0; font-size: 13px; color: #bfdbfe; }
.social-col ul { list-style: none; margin: 0; padding: 0; }
.social-col ul li { margin-bottom: 6px; font-size: 13px; color: #bfdbfe; }