* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: #f4f7fb;
  color: #1f2933;
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 18px 8%;
  background: #0f172a;
  color: white;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: white;
  text-decoration: none;
  font-weight: bold;
  font-size: 1.2rem;
}

.logo {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  background: #38bdf8;
  color: #0f172a;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  font-size: 0.95rem;
}

nav {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 22px;
}

nav a {
  color: white;
  text-decoration: none;
}

nav a:hover,
nav a:focus {
  color: #93c5fd; 
}

nav a.active {
  color: #38bdf8; 
}

.hero {
  text-align: center;
  padding: 90px 12%;
  background: linear-gradient(135deg, #1e3a8a, #0f172a);
  color: white;
}

.hero h1 {
  font-size: 2.6rem;
  margin: 0 0 16px;
}

.hero p {
  font-size: 1.1rem;
  line-height: 1.7;
  max-width: 720px;
  margin: 0 auto;
}

.rng-container {
  text-align: center;
  padding: 60px 20px 80px;
}

.rng-container h2 {
  margin-bottom: 12px;
}

.rng-container p {
  margin-bottom: 30px;
  font-size: 1.05rem;
  line-height: 1.6;
}

.number-box {
  width: 260px;
  height: 120px;
  margin: 0 auto 30px;
  background: white;
  border-radius: 14px;
  box-shadow: 0 8px 24px rgba(15, 23, 42, 0.08);
  display: flex;
  justify-content: center;
  align-items: center;
}

#number {
  font-size: 4rem;
  font-weight: bold;
  color: #1e3a8a;
}

button {
  background: #38bdf8;
  color: #0f172a;
  border: none;
  padding: 12px 22px;
  border-radius: 8px;
  font-weight: bold;
  cursor: pointer;
}

button:hover,
button:focus {
  background: #7dd3fc;
}

footer {
  text-align: center;
  padding: 22px;
  background: #0f172a;
  color: white;
}

@media (max-width: 900px) {
  .navbar {
    flex-direction: column;
    gap: 18px;
  }

  nav {
    justify-content: center;
  }
}

@media (max-width: 600px) {
  .hero {
    padding: 60px 8%;
  }

  .hero h1 {
    font-size: 2rem;
  }

  nav {
    flex-direction: column;
    gap: 12px;
  }

  .number-box {
    width: min(260px, 100%);
  }
}