html, body {
  height: 100%;
  margin: 0;
  display: flex;
  flex-direction: column;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #0d1b2a;
  color: #ffffff;
  line-height: 1.6;
}

header {
  padding: 30px 20px;
  text-align: center;
  background-color: #1b263b;
}

header h1 {
  margin: 0;
  font-size: 2.5em;
  color: #ffffff;
}

header p {
  margin-top: 10px;
  color: #a9bcd0;
}

main {
  flex: 1 0 auto;
  overflow-y: auto;
}

.container {
  width: 100%;
  max-width: 500px;
  margin: 40px auto 0;
  padding: 0 20px 100px;
  box-sizing: border-box;
}

label {
  display: block;
  margin-top: 25px;
  font-weight: 600;
  color: #cbd5e1;
}

select,
input[type="number"] {
  display: block;
  width: 100%;
  box-sizing: border-box;
  margin-top: 8px;
  padding: 12px;
  background-color: #1e293b;
  border: 2px solid #334155;
  border-radius: 6px;
  font-size: 1em;
  color: #e2e8f0;
  transition: border-color 0.2s ease;
}

select:focus,
input[type="number"]:focus {
  border-color: #3b82f6;
  outline: none;
}

button {
  margin-top: 30px;
  width: 100%;
  padding: 15px;
  background-color: #3b82f6;
  border: none;
  border-radius: 6px;
  font-size: 1.1em;
  font-weight: 600;
  color: #ffffff;
  cursor: pointer;
  transition: background-color 0.3s ease;
}

button:hover {
  background-color: #2563eb;
}

#result {
  min-height: 2em;
  margin-top: 30px;
  font-size: 1em;
  text-align: center;
  color: #ffffff;
  word-wrap: break-word;
  overflow-wrap: break-word;
  max-width: 100%;
}

footer {
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  background-color: #1b263b;
  color: #94a3b8;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px 0;
  font-size: 0.9em;
  z-index: 10;
  box-sizing: border-box;
}

footer a {
  color: #60a5fa;
  text-decoration: none;
  margin: 0;
  padding: 0;
}

footer a:hover {
  text-decoration: underline;
}