body {
  margin: 0;
  background: #111;
  color: #eee;
  font-family: Arial, sans-serif;
}

a {
  color: #7cf;
  text-decoration: none;
}

/* ===== KHUNG NOI DUNG ===== */
.khung {
  width: 100%;
  max-width: none;
  margin: 0;
  padding: 40px 60px;
  background: #1a1a1a;

  font-size: 20px;      /* tăng font */
  line-height: 2;       /* dễ đọc */
  box-sizing: border-box;
}




/* ===== MENU FIXED (JS SE CANH GIUA) ===== */
.menu {
  position: fixed;
  top: 0;               /* JS sẽ set lại */
  background: rgba(20,20,20,0.95);
  padding: 8px 6px;
  z-index: 9999;

  opacity: 1;
  transition: opacity 0.3s ease;
}

.menu a {
  display: block;
  padding: 6px 10px;
  font-weight: bold;
  font-size: 14px;
  white-space: nowrap;
}

.menu a:hover {
  background: rgba(255,255,255,0.08);
}

/* ===== CUM TRAI / PHAI ===== */
.cum-trai {
  left: 0;
  border-radius: 0 6px 6px 0;
}

.cum-phai {
  right: 0;
  border-radius: 6px 0 0 6px;
}

/* ===== FORM THEM / SUA CHUONG ===== */
form {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

input[type="text"],
input[name="tieu_de"] {
  width: 100%;
  padding: 8px;
  font-size: 14px;
  background: #222;
  color: #eee;
  border: 1px solid #333;
  box-sizing: border-box;
}

textarea {
  width: 100%;
  min-height: 400px;
  padding: 10px;
  font-size: 14px;
  background: #222;
  color: #eee;
  border: 1px solid #333;
  resize: vertical;
  box-sizing: border-box;
}

button {
  align-self: flex-end;
  padding: 6px 16px;
  font-size: 14px;
  cursor: pointer;
  background: #333;
  color: #eee;
  border: 1px solid #444;
}

button:hover {
  background: #444;
}