:root {
  --primary-color: #007bff;
  --secondary-color: #0056b3;
  --background-color: #f4f7f6;
  --card-bg-color: #ffffff;
  --text-color: #333333;
  --text-light-color: #6c757d;
  --border-color: #e0e0e0;
  --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --box-shadow-light: 0 4px 15px rgba(0, 0, 0, 0.05);
  --box-shadow-dark: 0 8px 30px rgba(0, 0, 0, 0.1);
  --border-radius: 12px;
  --input-bg-color: #f8f9fa;
  --input-border-color: #ced4da;
  --focus-glow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--background-color);
  color: var(--text-color);
  margin: 0;
  padding: 0;
  line-height: 1.6;
  transition: background-color 0.3s ease;
}

header {
  background-color: var(--card-bg-color);
  padding: 2rem 1rem;
  text-align: center;
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--box-shadow);
  margin-bottom: 2rem;
  position: sticky;
  top: 0;
  z-index: 1000;
}

h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin: 0;
  color: var(--primary-color);
}

main {
  padding: 1rem;
  max-width: 1200px;
  margin: auto;
}

.button-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2.5rem;
}

.tool-button {
  background-color: var(--card-bg-color);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  padding: 1.5rem 1rem;
  cursor: pointer;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-color);
  transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  text-decoration: none;
  box-shadow: var(--box-shadow-light);
}

.tool-button i {
    font-size: 2rem;
    margin-bottom: 0.75rem;
    color: var(--primary-color);
    transition: color 0.3s ease;
}

.tool-button:hover, .tool-button.active {
  background-color: var(--primary-color);
  color: white;
  transform: translateY(-5px);
  box-shadow: var(--box-shadow-dark);
  border-color: var(--primary-color);
}

.tool-button:hover i, .tool-button.active i {
  color: white;
}

#tool-container {
  background-color: var(--card-bg-color);
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow-dark);
  border: 1px solid var(--border-color);
  animation: fadeIn 0.5s ease-in-out;
}

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

/* Common styles for tool content */
.tool-content {
  max-width: 600px;
  margin: auto;
  text-align: center;
}
.tool-content h2 {
  font-size: 2rem;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
  font-weight: 700;
}
.tool-content .tool-description {
  color: var(--text-light-color);
  margin-bottom: 2rem;
  font-size: 1rem;
}
.tool-content .input-group {
  margin-bottom: 1.5rem;
  text-align: left;
}
.tool-content label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--text-color);
}
.tool-content .tool-input, .tool-content select {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--input-border-color);
  border-radius: 8px;
  font-size: 1rem;
  box-sizing: border-box;
  background-color: var(--input-bg-color);
  color: var(--text-color);
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}
.tool-content .tool-input:focus, .tool-content select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: var(--focus-glow);
}
.tool-content .tool-action-button {
  background-color: var(--primary-color);
  color: white;
  padding: 1rem 2rem;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-size: 1rem;
  font-weight: 600;
  transition: transform 0.2s ease, background-color 0.3s ease, box-shadow 0.3s ease;
  box-shadow: 0 4px 15px rgba(0, 123, 255, 0.2);
}
.tool-content .tool-action-button:hover {
  background-color: var(--secondary-color);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 123, 255, 0.3);
}
.tool-content .tool-result {
  margin-top: 2rem;
  padding: 1.5rem;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background-color: var(--input-bg-color);
  min-height: 50px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  font-weight: 500;
  color: var(--text-color);
}

/* Loading state animation */
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.loading-spinner {
  border: 4px solid var(--input-border-color);
  border-top: 4px solid var(--primary-color);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  animation: spin 1s linear infinite;
  margin: auto;
}
.loading-state p {
    color: var(--text-light-color);
}

@media (max-width: 768px) {
  .button-container {
    grid-template-columns: 1fr 1fr;
  }
  h1 {
    font-size: 2rem;
  }
  #tool-container {
    padding: 1.5rem;
  }
  .tool-content h2 {
    font-size: 2rem;
  }
  .tool-content .tool-action-button {
      width: 100%;
  }
}