* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: system-ui, sans-serif;
}

body {
  min-height: 100vh;
  background: radial-gradient(circle at top, #222 0%, #000 60%);
  color: white;
  display: flex;
  flex-direction: column;
  align-items: center;
}


/* ---------- NAVBAR ---------- */
.navbar {
  width: 100%;
  height: 64px;
  padding: 0 2rem;
  position: fixed;
  top: 0;
  left: 0;
  background: rgba(0, 0, 0, 0.65);
  backdrop-filter: blur(10px);
  display: flex;
  justify-content: space-between;
  align-items: center;
  z-index: 10;
}

.nav-brand {
  font-size: 1.5rem;
  font-weight: bold;
  letter-spacing: 1px;
}

/* ---------- NAVBAR LOGO ---------- */
.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.nav-logo {
  width: 45px;
  height: 45px;
  max-width: 45px;
  max-height: 45px;
  object-fit: contain;
  display: block;
}


/* LINKS */
.nav-links {
  list-style: none;
  display: flex;
  gap: 2rem;
}

.nav-links li a {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  text-decoration: none;
  color: white;
  opacity: 0.85;
  font-size: 0.95rem;
  transition: opacity 0.2s ease, transform 0.2s ease;
  font-weight: bold;
  transition: all 0.15s ease;
}

/* ICONS */
.nav-links li a i {
  font-size: 1.3rem;
  opacity: 0.9;
}

/* HOVER */
.nav-links li a:hover {
  opacity: 1;
  transform: translateY(-2px);
}

/* ---------- GAME ---------- */
.game-container {
  margin-top: 6rem;
  text-align: center;
}

h1 {
  font-size: 3rem;
  letter-spacing: 2px;
  margin-bottom: 0.5rem;
}

.info h2 {
  font-size: 1.1rem;
  font-weight: 400;
  opacity: 0.85;
  margin-bottom: 0.5rem;
}

/* ---------- GAME BOARD ---------- */
.board {
  margin-top: 2rem;
}

.first_line,
.second_line {
  display: flex;
  justify-content: center;
}

/* ---------- BUTTONS ---------- */
.btn {
  cursor: pointer;
  width: 10rem;
  height: 10rem;
  margin: 1.5rem;
  border-radius: 2rem;
  box-shadow: 0 0 25px rgba(0, 0, 0, 0.6);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.btn:active {
  transform: scale(0.95);
}

/* ---------- COLORS ---------- */
.red {
  background: linear-gradient(145deg, #ff4b4b, #c70000);
}

.cyan {
  background: linear-gradient(145deg, #00f2ff, #008b91);
}

.orange {
  background: linear-gradient(145deg, #ffa94d, #ff7a00);
}

.purple {
  background: linear-gradient(145deg, #b97cff, #6a00ff);
}

/* ---------- FLASH EFFECTS ---------- */
.flash {
  filter: brightness(2);
  box-shadow: 0 0 40px white;
}

.userFlash {
  filter: brightness(1.6);
  box-shadow: 0 0 40px rgba(0, 150, 255, 0.9);
}

/* ---------- FOOTER ---------- */
.footer {
  width: 100%;
  margin-top: auto;
  padding: 0.8rem 0;
  text-align: center;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(8px);
  font-size: 0.9rem;
  opacity: 0.85;
}

.footer span {
  font-weight: bold;
  opacity: 1;
}

/* ---------- RESPONSIVE ---------- */
@media (max-width: 600px) {
  /* NAVBAR */
  .navbar {
    padding: 0 1rem;
  }

  .nav-brand {
    font-size: 1.2rem;
  }

  .nav-links {
    gap: 1rem;
  }

  .nav-links li a {
    font-size: 0.8rem;
  }

  .nav-links li a i {
    font-size: 1.1rem;
  }

  /* GAME BUTTONS */
  .btn {
    width: 6.5rem;
    height: 6.5rem;
    margin: 0.8rem;
    border-radius: 1.3rem;
  }

  h1 {
    font-size: 2rem;
  }
}

@media (max-width: 450px) {
  .nav-links li a {
    font-size: 0;
  }

  .nav-links li a i {
    font-size: 1.4rem;
  }
}