:root {
  --bg-gradient: linear-gradient(135deg, #0d0d1a, #16213e 45%, #533483);
  --card-bg: rgba(255, 255, 255, 0.96);
  --accent: #ffb703;
  --accent-dark: #fb8500;
  --text-primary: #1b1b1f;
  --text-secondary: #505263;
  --border-radius: 18px;
  --shadow: 0 18px 40px -25px rgba(15, 23, 42, 0.6);
  --transition: 150ms ease-in-out;
  --font-base: 'Inter', 'Segoe UI', Roboto, sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-base);
  color: var(--text-primary);
  background: var(--bg-gradient);
  display: flex;
  flex-direction: column;
  align-items: center;
}

header {
  width: min(1100px, 92vw);
  padding: 4rem 0 2rem;
  text-align: center;
  color: #f8f9ff;
}

header h1 {
  margin: 0;
  font-size: clamp(2.2rem, 4vw, 3.4rem);
  font-weight: 700;
  letter-spacing: -0.02em;
}

header p {
  margin: 0.75rem auto 0;
  max-width: 620px;
  font-size: 1.05rem;
  line-height: 1.6;
  color: rgba(248, 249, 255, 0.78);
}

main {
  width: min(1100px, 92vw);
  display: grid;
  gap: 2rem;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  padding-bottom: 4rem;
}

.card {
  background: var(--card-bg);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
  padding: 2.2rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  position: relative;
  overflow: hidden;
}

.card::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: radial-gradient(circle at top right, rgba(255, 183, 3, 0.18), transparent 55%);
  pointer-events: none;
}

.card h2 {
  margin: 0;
  font-size: 1.7rem;
  font-weight: 600;
}

.form-row {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

label {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
  display: block;
  margin-bottom: 0.35rem;
}

input[type="number"],
input[type="date"],
select {
  width: 100%;
  padding: 0.85rem 1rem;
  border-radius: 12px;
  border: 1px solid rgba(15, 23, 42, 0.1);
  background: rgba(255, 255, 255, 0.9);
  font-size: 1rem;
  transition: border-color var(--transition), box-shadow var(--transition);
}

input:focus,
select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(255, 183, 3, 0.25);
}

button {
  align-self: flex-start;
  padding: 0.85rem 1.6rem;
  border-radius: 999px;
  border: none;
  background: var(--accent);
  color: #121217;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: transform var(--transition), background var(--transition), box-shadow var(--transition);
  box-shadow: 0 12px 25px -15px rgba(251, 133, 0, 0.8);
}

button:hover {
  transform: translateY(-1px);
  background: var(--accent-dark);
}

button:focus-visible {
  outline: 3px solid rgba(255, 183, 3, 0.6);
  outline-offset: 3px;
}

.result-display {
  background: rgba(248, 249, 255, 0.9);
  border-radius: 14px;
  padding: 1.1rem 1.3rem;
  font-size: 1.1rem;
  line-height: 1.5;
  border: 1px solid rgba(15, 23, 42, 0.08);
  color: var(--text-secondary);
}

.result-display strong {
  color: var(--text-primary);
  font-size: 1.25rem;
}

.helper-text {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

#conversionRate {
  font-size: 0.95rem;
  color: var(--text-secondary);
}

footer {
  padding: 1.5rem 0 3rem;
  text-align: center;
  color: rgba(248, 249, 255, 0.75);
  font-size: 0.95rem;
}

footer a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 600;
}

@media (max-width: 720px) {
  header {
    padding-top: 3rem;
  }

  main {
    gap: 1.5rem;
  }

  .card {
    padding: 1.8rem;
  }
}