:root {
  --font-main: 'Inter', system-ui, sans-serif;

  /* Light Mode */
  --bg-gradient-start: #f0f2f5;
  --bg-gradient-end: #e6e9ee;
  --card-bg: rgba(255, 255, 255, 0.6);
  --card-border: rgba(255, 255, 255, 0.9);
  --text-primary: #1a202c;
  --text-secondary: #4a5568;
  --accent-color: #3b82f6;
  --accent-hover: #2563eb;
  --button-bg: #edf2f7;
  --button-shadow: 5px 5px 10px #d4d9e0, -5px -5px 10px #ffffff;
  --button-shadow-inset: inset 5px 5px 10px #d4d9e0, inset -5px -5px 10px #ffffff;
  --icon-color: #4a5568;
}

[data-theme='dark'] {
  --bg-gradient-start: #1a202c;
  --bg-gradient-end: #2d3748;
  --card-bg: rgba(45, 55, 72, 0.5);
  --card-border: rgba(255, 255, 255, 0.1);
  --text-primary: #edf2f7;
  --text-secondary: #a0aec0;
  --accent-color: #60a5fa;
  --accent-hover: #3b82f6;
  --button-bg: #2d3748;
  --button-shadow: 5px 5px 10px #1a202c, -5px -5px 10px #404c5c;
  --button-shadow-inset: inset 5px 5px 10px #1a202c, inset -5px -5px 10px #404c5c;
  --icon-color: #a0aec0;
}

body {
  font-family: var(--font-main);
  color: var(--text-primary);
  transition: background-color 0.3s ease, color 0.3s ease;
  background-color: var(--bg-gradient-start);
}

.background-gradient {
  position: fixed; top: 0; left: 0; width: 100%; height: 100%;
  background-image: linear-gradient(120deg, var(--bg-gradient-start), var(--bg-gradient-end));
  z-index: -1;
}

.app-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 2rem;
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--card-border);
}

.logo {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-primary);
  text-decoration: none;
}

.nav-links {
  display: flex;
  gap: 2rem;
}

.nav-links a {
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.2s ease;
}

.nav-links a:hover {
  color: var(--accent-color);
}

.theme-switcher {
  position: relative;
}

.theme-switcher input {
  display: none;
}

.theme-switcher label {
  cursor: pointer;
  color: var(--icon-color);
}

.sun-icon, .moon-icon {
  transition: opacity 0.3s ease, transform 0.4s ease;
}

.moon-icon {
  position: absolute;
  top: 0;
  left: 0;
  opacity: 0;
  transform: scale(0.8);
}

#theme-toggle:checked ~ label .sun-icon {
  opacity: 0;
  transform: scale(0.8) rotate(90deg);
}

#theme-toggle:checked ~ label .moon-icon {
  opacity: 1;
  transform: scale(1) rotate(0);
}

main {
    padding: 1rem;
}

.tool-header {
    text-align: center;
    margin-bottom: 1.5rem;
}
.tool-header h1 { font-size: 2rem; font-weight: 700; }
.tool-header p { font-size: 1rem; color: var(--text-secondary); }

.app-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem; /* Add horizontal padding */
}

@media (max-width: 768px) {
    .app-container { grid-template-columns: 1fr; }
    main { padding: 0.5rem; }
    .tool-header h1 { font-size: 1.75rem; }
    .tool-header p { font-size: 0.9rem; }
}