:root {
  --brand: #c62828; /* đỏ chủ đạo */
  --bg: #f9fafb;
  --card: #fff;
  --text: #111827;
  --muted: #6b7280;

  --header-height: 60px;       /* chiều cao header */
  --bottom-nav-height: 60px;   /* chiều cao bottom nav */
}

body {
  margin: 0;
  font-family: "Inter", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  padding-bottom: var(--bottom-nav-height);
  transition: background .3s, color .3s;
}

/* ===== MAIN LAYOUT ===== */
main {
  display: flex;
  flex-direction: column;
  min-height: calc(100vh - (var(--header-height) + var(--bottom-nav-height)));
  padding: 0 16px;
  box-sizing: border-box;
}

/* ===== WELCOME ===== */
.welcome {
  flex: 0 0 auto;
  margin: 16px 0;
  text-align: center;
}
.welcome h1 {
  font-size: 38px; /* x2 */
  margin: 16px 0;
  line-height: 1.2;
}
.welcome p {
  font-size: 20px; /* x2 */
  line-height: 1.3;
  margin: 0;
}

/* ===== CARDS ===== */
.cards {
  flex: 1 1 auto;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  padding-bottom: 16px;
}
@media (min-width: 1024px) {
  .cards { grid-template-columns: repeat(3, 1fr); }
}
@media (min-width: 1280px) {
  .cards { grid-template-columns: repeat(4, 1fr); }
}
.card {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;

  background: var(--card);
  padding: 28px;
  border-radius: 14px;
  text-align: center;
  box-shadow: 0 4px 10px rgba(0,0,0,0.05);
  cursor: pointer;
  transition: transform .2s, box-shadow .2s;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 6px 14px rgba(0,0,0,0.1);
}
.card i {
  font-size: 43px; /* x2 */
  margin-bottom: 12px;
  color: var(--brand);
  display: block;
}
.card h3 {
  font-size: 23px; /* x2 */
  margin: 0 0 8px;
  line-height: 1.2;
}
.card p {
  font-size: 15px; /* x2 */
  margin: 0;
  line-height: 1.2;
}

/* ===== ACCESSIBILITY ===== */
.accessibility { position: relative; display: inline-block; }
#accToggle {
  background: none; border: none; font-size: 36px; /* x2 */
  cursor: pointer; color: inherit;
}
.acc-menu {
  position: absolute; top: 42px; right: 0;
  background: var(--card); border: 1px solid #ddd;
  border-radius: 10px; box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  padding: 16px;
  display: flex; flex-direction: column; gap: 12px;
  z-index: 999; min-width: 300px;
}
.acc-menu button {
  display: flex; align-items: center; gap: 16px;
  background: #f9fafb; color: var(--text);
  border: none; padding: 16px 20px;
  border-radius: 8px;
  cursor: pointer; font-size: 28px; /* x2 */
  transition: background .2s;
}
.acc-menu button:hover { background: #fde0e0; }

/* ===== POPUP ===== */
.popup-overlay {
  display: none; position: fixed; inset: 0;
  background: rgba(0,0,0,0.6);
  align-items: center; justify-content: center;
  z-index: 2000;
}
.popup-content {
  background: #fff; padding: 48px; /* x2 */
  border-radius: 12px;
  width: 90%; max-width: 760px;
  text-align: center;
  animation: fadeIn .3s ease; position: relative;
}
.popup-close {
  position: absolute; top: 24px; right: 32px;
  border: none; background: none; font-size: 44px; /* x2 */
  cursor: pointer;
}
.login-options {
  margin-top: 40px; display: flex; flex-direction: column; gap: 24px;
}
.login-btn {
  display: flex; align-items: center; justify-content: center;
  gap: 20px; padding: 24px;
  border-radius: 8px;
  text-decoration: none; font-weight: 600;
  font-size: 20px; /* x2 */
  transition: .2s;
}
.login-btn.google { background: #db4437; color: #fff; }
.login-btn.zalo { background: var(--brand); color: #fff; }
.login-btn:hover { opacity: 0.9; }

@keyframes fadeIn {
  from { transform: translateY(-20px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

/* ===== HẾT CODE ===== */