/* CSS Variables and Theme Definitions */
:root {
  /* Default Theme (Light) */
  --bg-color: #f8fafc;
  --header-bg: #ffffff;
  --text-color: #0f172a;
  --text-secondary: #475569;
  --primary-color: #3b82f6;
  --primary-hover: #2563eb;
  --primary-light: #eff6ff;
  --border-color: #e2e8f0;
  --card-bg: #ffffff;
  --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --focus-ring: 0 0 0 3px rgba(59, 130, 246, 0.3);
  --textarea-bg: #ffffff;
  --transition-speed: 0.2s;
  --panel-bg: #ffffff;
  --success-color: #10b981;
  --success-hover: #059669;
  --warning-bg: #fef3c7;
  --warning-border: #f59e0b;
  --warning-text: #b45309;
}

/* Explicit Dark Theme */
[data-theme="dark"] {
  --bg-color: #0f172a;
  --header-bg: #1e293b;
  --text-color: #f8fafc;
  --text-secondary: #94a3b8;
  --primary-color: #3b82f6;
  --primary-hover: #60a5fa;
  --primary-light: #1e293b;
  --border-color: #334155;
  --card-bg: #1e293b;
  --card-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.3), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
  --focus-ring: 0 0 0 3px rgba(59, 130, 246, 0.5);
  --textarea-bg: #1e293b;
  --panel-bg: #1e293b;
}

/* Sepia Theme (warm paper writing tones) */
[data-theme="sepia"] {
  --bg-color: #f4ecd8;
  --header-bg: #eae0ca;
  --text-color: #433422;
  --text-secondary: #6d5d4b;
  --primary-color: #b45309;
  --primary-hover: #92400e;
  --primary-light: #f5eacf;
  --border-color: #d6c8b1;
  --card-bg: #fdf6e2;
  --card-shadow: 0 4px 6px -1px rgba(67, 52, 34, 0.05), 0 2px 4px -2px rgba(67, 52, 34, 0.05);
  --focus-ring: 0 0 0 3px rgba(180, 83, 9, 0.4);
  --textarea-bg: #fdf6e2;
  --panel-bg: #fdf6e2;
}

/* Forest Theme (Sage Green Theme) */
[data-theme="forest"] {
  --bg-color: #f1f7f5;
  --header-bg: #ffffff;
  --text-color: #14532d;
  --text-secondary: #334155;
  --primary-color: #10b981;
  --primary-hover: #059669;
  --primary-light: #f0fdf4;
  --border-color: #cbd5e1;
  --card-bg: #ffffff;
  --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --focus-ring: 0 0 0 3px rgba(16, 185, 129, 0.4);
  --textarea-bg: #ffffff;
}

/* Ocean Blue Theme */
[data-theme="ocean"] {
  --bg-color: #f0f9ff;
  --header-bg: #ffffff;
  --text-color: #0369a1;
  --text-secondary: #334155;
  --primary-color: #0284c7;
  --primary-hover: #0369a1;
  --primary-light: #f0f9ff;
  --border-color: #bae6fd;
  --card-bg: #ffffff;
  --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --focus-ring: 0 0 0 3px rgba(2, 132, 199, 0.4);
  --textarea-bg: #ffffff;
}

/* Reset and Base Styles */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  height: 100%;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease;
}

/* Accessibility Skip Link */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--primary-color);
  color: white;
  padding: 8px;
  z-index: 1100;
  transition: top 0.2s;
  text-decoration: none;
  border-bottom-right-radius: 4px;
}

.skip-link:focus {
  top: 0;
  outline: none;
  box-shadow: var(--focus-ring);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Sticky Navigation Bar */
.app-nav {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: var(--header-bg);
  border-bottom: 1px solid var(--border-color);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
  transition: background-color var(--transition-speed) ease, border-color var(--transition-speed) ease;
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 4.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--text-color);
  font-weight: 800;
  font-size: 1.35rem;
  letter-spacing: -0.025em;
  transition: color var(--transition-speed) ease;
}

.nav-logo .logo-icon {
  width: 1.75rem;
  height: 1.75rem;
  color: var(--primary-color);
}

/* Navigation Links */
.nav-links {
  display: flex;
  gap: 1.5rem;
}

.nav-link {
  text-decoration: none;
  color: var(--text-secondary);
  font-weight: 600;
  font-size: 0.95rem;
  padding: 0.5rem 0;
  border-bottom: 2px solid transparent;
  transition: color var(--transition-speed) ease, border-color var(--transition-speed) ease;
}

.nav-link:hover {
  color: var(--primary-color);
}

.nav-link.active {
  color: var(--primary-color);
  border-bottom-color: var(--primary-color);
}

/* Mobile Hamburger Menu */
.nav-toggle {
  display: none;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.hamburger {
  display: block;
  width: 1.5rem;
  height: 2px;
  background: var(--text-color);
  position: relative;
  transition: background var(--transition-speed) ease;
}

.hamburger::before, .hamburger::after {
  content: '';
  display: block;
  width: 1.5rem;
  height: 2px;
  background: var(--text-color);
  position: absolute;
  left: 0;
  transition: transform var(--transition-speed) ease, top var(--transition-speed) ease, bottom var(--transition-speed) ease;
}

.hamburger::before { top: -6px; }
.hamburger::after { bottom: -6px; }

/* Hamburger Open State Anim */
.nav-toggle[aria-expanded="true"] .hamburger {
  background: transparent;
}
.nav-toggle[aria-expanded="true"] .hamburger::before {
  top: 0;
  transform: rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .hamburger::after {
  bottom: 0;
  transform: rotate(-45deg);
}

/* App Container */
.app-container {
  display: flex;
  flex-direction: column;
  min-height: calc(100vh - 4.5rem);
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header Styling */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  padding: 2rem 0 1.5rem 0;
  border-bottom: 1px solid var(--border-color);
  gap: 1.25rem;
}

.app-header h1 {
  font-size: 1.85rem;
  font-weight: 800;
  letter-spacing: -0.025em;
}

.tagline {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-top: 0.25rem;
}

/* Header Control Group Panel */
.header-controls {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  flex-wrap: wrap;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.control-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
}

.control-select {
  padding: 0.45rem 1.75rem 0.45rem 0.75rem;
  font-size: 0.875rem;
  font-weight: 600;
  background-color: var(--header-bg);
  color: var(--text-color);
  border: 1px solid var(--border-color);
  border-radius: 0.375rem;
  outline: none;
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%23475569'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.5rem center;
  background-size: 1rem;
  transition: border-color var(--transition-speed), background-color var(--transition-speed);
}

.control-select:focus-visible {
  border-color: var(--primary-color);
  box-shadow: var(--focus-ring);
}

/* Main Content Layout */
.app-main {
  flex: 1;
  padding: 2rem 0;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

/* Input Section */
.input-section {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.textarea-wrapper {
  position: relative;
  width: 100%;
}

textarea {
  width: 100%;
  min-height: 180px;
  max-height: 600px;
  padding: 1.25rem;
  font-family: inherit;
  font-size: 1.1rem;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--textarea-bg);
  border: 2px solid var(--border-color);
  border-radius: 0.75rem;
  resize: vertical;
  outline: none;
  box-shadow: var(--card-shadow);
  transition: border-color var(--transition-speed) ease, box-shadow var(--transition-speed) ease, font-size var(--transition-speed) ease;
}

textarea:focus {
  border-color: var(--primary-color);
  box-shadow: var(--focus-ring);
}

/* Font Size Modifiers for Textarea */
.font-small { font-size: 14px !important; }
.font-medium { font-size: 18px !important; }
.font-large { font-size: 24px !important; }

/* Action Bar below Textarea */
.action-bar {
  display: flex;
  justify-content: flex-end;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.625rem 1.25rem;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: 0.5rem;
  border: 1px solid transparent;
  cursor: pointer;
  background-color: transparent;
  transition: background-color var(--transition-speed) ease, border-color var(--transition-speed) ease, transform 0.1s ease;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background-color: var(--primary-color);
  color: #ffffff;
}

.btn-primary:hover {
  background-color: var(--primary-hover);
}

.btn-primary:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}

.btn-secondary {
  background-color: var(--header-bg);
  border-color: var(--border-color);
  color: var(--text-color);
}

.btn-secondary:hover {
  background-color: var(--border-color);
}

.btn-secondary:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}

.btn-success {
  background-color: var(--success-color) !important;
  color: white !important;
  border-color: var(--success-hover) !important;
}

.kbd-shortcut {
  font-size: 0.8rem;
  opacity: 0.7;
}

/* Stats Display Grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.25rem;
}

.stat-card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--card-shadow);
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow var(--transition-speed) ease;
}

.stat-card:hover {
  transform: translateY(-2px);
  border-color: var(--primary-color);
}

.stat-label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
}

.sub-label {
  font-size: 0.75rem;
  font-weight: normal;
  opacity: 0.85;
}

.stat-value {
  font-size: 2.15rem;
  font-weight: 800;
  color: var(--primary-color);
  margin-top: 0.5rem;
  word-break: break-all;
  line-height: 1.1;
  transition: color var(--transition-speed) ease;
}

/* Grammar Analysis Panel */
.grammar-panel {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  padding: 1.5rem;
  margin-top: 0.5rem;
  box-shadow: var(--card-shadow);
  transition: background-color var(--transition-speed) ease, border-color var(--transition-speed) ease;
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1.5px solid var(--border-color);
  padding-bottom: 0.75rem;
  margin-bottom: 1rem;
}

.panel-header h2 {
  font-size: 1.25rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.close-btn {
  background: transparent;
  border: none;
  font-size: 1.75rem;
  font-weight: bold;
  cursor: pointer;
  color: var(--text-secondary);
  transition: color var(--transition-speed);
  line-height: 1;
}

.close-btn:hover {
  color: var(--text-color);
}

.panel-content {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.grammar-issue-card {
  padding: 1rem;
  border-radius: 0.5rem;
  background-color: var(--warning-bg);
  border-left: 4px solid var(--warning-border);
  color: var(--warning-text);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.grammar-desc {
  font-size: 0.9rem;
  font-weight: 500;
}

.grammar-context {
  font-size: 0.8rem;
  opacity: 0.85;
  font-style: italic;
  margin-top: 0.25rem;
}

.grammar-fix-btn {
  background-color: var(--warning-border);
  color: white;
  border: none;
  padding: 0.35rem 0.75rem;
  font-size: 0.8rem;
  font-weight: 700;
  border-radius: 0.25rem;
  cursor: pointer;
  transition: opacity 0.15s;
}

.grammar-fix-btn:hover {
  opacity: 0.9;
}

.grammar-success-state {
  text-align: center;
  padding: 1.5rem 0;
  color: var(--success-color);
  font-weight: 600;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
}

/* Static Content Pages layout (About, More Tools, Contact) */
.content-wrapper {
  max-width: 800px;
  margin: 0 auto;
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.page-title {
  font-size: 2.25rem;
  font-weight: 800;
  letter-spacing: -0.025em;
  margin-bottom: 0.5rem;
}

.static-section {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  padding: 2rem;
  box-shadow: var(--card-shadow);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.static-section h2 {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.015em;
}

.static-section p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  line-height: 1.7;
}

.static-section ul {
  list-style-type: none;
  padding-left: 0;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.static-section li {
  color: var(--text-secondary);
  font-size: 1.05rem;
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
}

.static-section li::before {
  content: "✦";
  color: var(--primary-color);
  font-weight: bold;
}

/* More Tools Cards */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
}

.tool-card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.75rem;
  padding: 1.5rem;
  box-shadow: var(--card-shadow);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  text-decoration: none;
  color: inherit;
  transition: transform 0.2s, border-color 0.2s;
}

.tool-card:hover {
  transform: translateY(-3px);
  border-color: var(--primary-color);
}

.tool-status {
  align-self: flex-start;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.2rem 0.5rem;
  border-radius: 9999px;
  text-transform: uppercase;
}

.status-active {
  background-color: var(--primary-light);
  color: var(--primary-color);
}

.status-soon {
  background-color: var(--border-color);
  color: var(--text-secondary);
}

.tool-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
}

.tool-card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* Contact Form */
.contact-form {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.form-group label {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-color);
}

.form-control {
  width: 100%;
  padding: 0.75rem 1rem;
  font-size: 1rem;
  background-color: var(--textarea-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  color: var(--text-color);
  outline: none;
  transition: border-color var(--transition-speed);
}

.form-control:focus {
  border-color: var(--primary-color);
  box-shadow: var(--focus-ring);
}

.form-textarea {
  min-height: 120px;
  resize: vertical;
}

.form-success-alert {
  background-color: var(--primary-light);
  border: 1px solid var(--primary-color);
  color: var(--text-color);
  padding: 1rem;
  border-radius: 0.5rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* App Footer */
.app-footer {
  padding: 2.5rem 0 2rem 0;
  border-top: 1px solid var(--border-color);
  margin-top: auto;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.footer-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 0.75rem;
}

.privacy-note {
  font-size: 0.9rem;
}

.copyright {
  font-weight: 500;
}

.affiliate-area {
  margin-top: 0.5rem;
  max-width: 600px;
  line-height: 1.6;
  opacity: 0.85;
}

.affiliate-area a {
  color: var(--primary-color);
  text-decoration: underline;
  font-weight: 500;
}

.affiliate-area a:hover {
  opacity: 0.8;
}

/* Media Queries for Responsiveness */

/* Tablets / Medium Devices */
@media (max-width: 768px) {
  /* Navigation Bar Mobile Layout */
  .nav-links {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 4.5rem;
    left: 0;
    right: 0;
    background-color: var(--header-bg);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 1.5rem;
    gap: 1rem;
    box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1);
  }
  
  .nav-links.open {
    display: flex;
  }
  
  .nav-link {
    padding: 0.25rem 0;
    border-bottom: none;
  }
  
  .nav-toggle {
    display: block;
  }
  
  .app-header {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .header-controls {
    width: 100%;
  }
  
  .control-group {
    flex: 1;
    min-width: 120px;
  }
  
  .control-select {
    width: 100%;
  }
}

/* Small Screens */
@media (max-width: 576px) {
  .action-bar {
    justify-content: stretch;
  }
  
  .action-bar .btn {
    flex: 1;
    justify-content: center;
  }
}