/* Reset & basic */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Helvetica Neue', Arial, sans-serif;
  background: #0f172a;
  color: white;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  padding: 15px;
}

.app {
  background: #020617;
  width: 100%;
  max-width: 400px;
  border-radius: 20px;
  padding: 25px;
  box-shadow: 0 8px 25px rgba(0,0,0,0.5);
}

h1 {
  text-align: center;
  margin-bottom: 25px;
  font-size: 24px;
  color: #38bdf8;
}

.input-group {
  margin-bottom: 15px;
}

.input-group label {
  display: block;
  margin-bottom: 5px;
  font-size: 14px;
  color: #94a3b8;
}

input, select {
  width: 100%;
  padding: 14px;
  border-radius: 12px;
  border: none;
  font-size: 16px;
  background: #1e293b;
  color: white;
}

input[type=number]::-webkit-inner-spin-button,
input[type=number]::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}
input[type=number] {
  -moz-appearance: textfield;
}

button {
  width: 100%;
  padding: 14px;
  border-radius: 14px;
  border: none;
  font-size: 16px;
  font-weight: bold;
  margin-bottom: 12px;
  cursor: pointer;
  transition: 0.3s;
}

.calculate-btn {
  background: #2563eb;
}

.calculate-btn:hover {
  background: #1d4ed8;
}

.download-btn {
  background: #10b981;
}

.download-btn:hover {
  background: #059669;
}

#result {
  margin-top: 20px;
  text-align: center;
}

#result p {
  margin: 6px 0;
  font-weight: bold;
  font-size: 16px;
}

#line1 { color: #38bdf8; }
#line2 { color: #f97316; }
#line3 { color: #22c55e; }

.footer {
  text-align: center;
  font-size: 12px;
  margin-top: 15px;
  color: #94a3b8;
}