:root {
  --bg: #f7f9fc;
  --card-bg: #fff;
  --text: #1a1a1a;
  --accent: #2563eb;
  --error: #b00020;
  --success: #0b6;
  --radius: 14px;
  --shadow: 0 8px 20px rgba(0,0,0,0.05);
}

* { box-sizing: border-box; }

body {
  font-family: "Inter", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  min-height: 100vh;
  padding: 2rem 1rem;
}

.container {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  width: 100%;
  max-width: 600px;
  padding: 2rem;
  animation: fadeIn 0.5s ease;
}

header { text-align: center; margin-bottom: 2rem; }
h1 { margin: 0; font-size: 2rem; color: var(--accent); }
.subtitle { margin-top: .25rem; color: #555; }

.label { display: block; margin-bottom: .5rem; font-weight: 600; }
.input-row { display: flex; gap: .5rem; }
input {
  flex: 1;
  padding: .6rem .75rem;
  border: 1px solid #ccc;
  border-radius: var(--radius);
  font: inherit;
  transition: border .2s ease;
}
input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(37,99,235,.2);
}
button {
  background: var(--accent);
  color: #fff;
  border: none;
  padding: .6rem 1.2rem;
  border-radius: var(--radius);
  font-weight: 600;
  cursor: pointer;
  transition: background .2s ease, transform .1s ease;
}
button:hover { background: #1e4ed8; }
button:active { transform: scale(.97); }
button:disabled { opacity: .6; cursor: progress; }

.result-section { margin-top: 2rem; }
.result-box {
  min-height: 3rem;
  border: 1px solid #e0e0e0;
  border-radius: var(--radius);
  padding: .75rem;
  background: #fafafa;
  margin-top: .5rem;
  transition: all .2s ease;
}
.result-box:focus { outline: 3px solid var(--accent); }

.status { margin-top: 1rem; font-weight: 500; }
.error { color: var(--error); }
.success { color: var(--success); }

/* Fade-in effect for result */
.result-box.fade-in { animation: fade 240ms ease; }
@keyframes fade { from {opacity:0; transform:translateY(2px)} to {opacity:1; transform:translateY(0)} }

footer {
  text-align: center;
  font-size: .85rem;
  margin-top: 2rem;
  color: #666;
}
footer a { color: var(--accent); text-decoration: none; }
footer a:hover { text-decoration: underline; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 480px) {
  .container { padding: 1.5rem; }
  input, button { font-size: 1rem; }
}