:root {
  --bg: #f3f4f6;
  --card-bg: #ffffff;
  --card-border: #d1d5db;
  --text: #1f2937;
  --text-muted: #6b7280;
  --accent: #3b82f6;
  --result-bg: #dbeafe;
  --result-text: #1e40af;
}

[data-theme="dark"] {
  --bg: #0f1117;
  --card-bg: #1a1d27;
  --card-border: #2a2e3d;
  --text: #e1e4ea;
  --text-muted: #8b92a5;
  --result-bg: #1e3a5f;
  --result-text: #93c5fd;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 24px;
  font-family: system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  transition: background-color 0.2s ease, color 0.2s ease;
  display: flex;
  flex-direction: column;
  align-items: center;
}

h1,
h2 {
  margin-top: 0;
}
h1 {
  margin-bottom: 8px;
  font-size: 1.8rem;
}
h2 {
  font-size: 1.1rem;
  border-bottom: 1px solid var(--card-border);
  padding-bottom: 8px;
}

.badge {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 16px;
  display: block;
}
.container {
  background: var(--card-bg);
  padding: 24px;
  border: 1px solid var(--card-border);
  border-radius: 8px;
  max-width: 600px;
  width: 100%;
  text-align: center;
  margin-bottom: 20px;
  position: relative;
}

input,
select,
button {
  width: 100%;
  padding: 10px 14px;
  border-radius: 8px;
  border: 1px solid var(--card-border);
  background: var(--card-bg);
  color: var(--text);
  font-size: 1rem;
  outline: none;
  transition: border-color 0.15s ease;
  box-sizing: border-box;
  appearance: none;
  -webkit-appearance: none;
}
input:focus,
select:focus {
  border-color: var(--accent);
}
button {
  cursor: pointer;
  transition: all 0.15s ease;
}
button:hover {
  border-color: var(--accent);
}
button.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

/* --- UNIFIED HEADER BUTTONS --- */
.theme-switch,
.back-btn {
  position: absolute;
  top: 1rem;
  cursor: pointer;
  padding: 8px 12px;
  border-radius: 8px;
  border: 1px solid var(--card-border);
  background: var(--card-bg);
  color: var(--text);
  font-size: 0.8rem;
  font-weight: 500;
  text-decoration: none;
  display: inline-block;
  width: auto;
  transition: all 0.15s ease;
}

.theme-switch {
  right: 1rem;
}

.back-btn {
  left: 1rem;
}

.theme-switch:hover,
.back-btn:hover {
  border-color: var(--accent);
}

.nav-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  max-width: 600px;
  width: 100%;
}
.nav-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 8px;
  padding: 24px;
  text-align: center;
  text-decoration: none;
  color: var(--text);
  transition: transform 0.15s ease, border-color 0.15s ease;
}
.nav-card:hover {
  transform: translateY(-2px);
  border-color: var(--accent);
}

@media (max-width: 480px) {
  .badge {
    margin-top: 36px;
  }
}

@media (max-width: 380px) {
  .container {
    display: flex;
    flex-direction: column;
    align-items: center;
  }

  .theme-switch,
  .back-btn {
    position: static;
    width: 100%;
    margin-bottom: 10px;
  }

  .theme-switch {
    order: -2;
  }
  .back-btn {
    order: -1;
  }

  .badge {
    margin-top: 8px;
  }
}

footer {
  margin-top: auto;
  padding-top: 24px;
  padding-bottom: 0px;
  margin-bottom: -8px;
  font-size: 0.85rem;
  color: var(--text-muted);
  text-align: center;
  width: 100%;
}