:root {
  --fb-blue: #1877f2;
  --bg: #f0f2f5;
  --card: #ffffff;
  --text: #050505;
  --muted: #65676b;
  --border: #dddfe2;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: var(--bg);
  color: var(--text);
}

/* Top Navbar */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 56px;
  background: var(--card);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  padding: 0 16px;
  z-index: 1000;
}

.logo {
  color: var(--fb-blue);
  font-size: 28px;
  font-weight: bold;
  margin-right: 16px;
}

.search {
  flex: 1;
  max-width: 320px;
  background: var(--bg);
  border-radius: 20px;
  padding: 8px 12px;
  font-size: 14px;
  border: none;
  outline: none;
}

/* Layout */
.container {
  display: grid;
  grid-template-columns: 280px 1fr 280px;
  gap: 16px;
  padding: 72px 16px 16px;
  max-width: 1200px;
  margin: auto;
}

/* Sidebars */
.sidebar {
  position: sticky;
  top: 72px;
}

.sidebar .item {
  padding: 10px;
  border-radius: 8px;
  cursor: pointer;
}

.sidebar .item:hover {
  background: #e4e6eb;
}

/* Feed */
.feed {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.card {
  background: var(--card);
  border-radius: 8px;
  padding: 12px;
  box-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

.post-header {
  display: flex;
  align-items: center;
  gap: 10px;
}

.avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: #ccc;
}

.name {
  font-weight: bold;
  font-size: 14px;
}

.time {
  font-size: 12px;
  color: var(--muted);
}

.post-content {
  margin: 12px 0;
  font-size: 15px;
}

.post-image {
  width: 100%;
  border-radius: 8px;
  background: #ddd;
  height: 220px;
}

.post-actions {
  display: flex;
  justify-content: space-around;
  border-top: 1px solid var(--border);
  padding-top: 8px;
  font-size: 14px;
  color: var(--muted);
}

.post-actions div {
  cursor: pointer;
  padding: 6px 0;
  flex: 1;
  text-align: center;
  border-radius: 4px;
}

.post-actions div:hover {
  background: #f0f2f5;
}

/* Responsive */
@media (max-width: 900px) {
  .container {
    grid-template-columns: 1fr;
  }
  .sidebar {
    display: none;
  }
}

/* Modal Overlay */
.modal {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 2000;
  align-items: center;
  justify-content: center;
}

/* Modal Box */
.modal-content {
  background: #fff;
  width: 360px;
  padding: 20px;
  border-radius: 8px;
  text-align: center;
  position: relative;
}

.modal-content h2 {
  margin-bottom: 16px;
}

.modal-content input {
  width: 100%;
  padding: 10px;
  margin-bottom: 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
}

.login-btn {
  width: 100%;
  padding: 10px;
  background: var(--fb-blue);
  color: #fff;
  border: none;
  border-radius: 6px;
  font-size: 16px;
  cursor: pointer;
}

.choice-btn {
  width: 100%;
  padding: 10px;
  background: var(--fb-blue);
  color: #fff;
  border: none;
  border-radius: 6px;
  font-size: 16px;
  cursor: pointer;
}

.signup-btn {
  margin-top: 10px;
  padding: 10px;
  width: 100%;
  background: #42b72a;
  color: #fff;
  border: none;
  border-radius: 6px;
  cursor: pointer;
}

.close {
  position: absolute;
  right: 12px;
  top: 10px;
  font-size: 22px;
  cursor: pointer;
}