/* CSS Variables for Themes */
:root {
  /* Ocean Theme (Default) */
  --bg-primary: #f0f9ff;
  --bg-secondary: #e0f2fe;
  --bg-card: #ffffff;
  --text-primary: #0c4a6e;
  --text-secondary: #075985;
  --text-muted: #0284c7;
  --accent-primary: #0ea5e9;
  --accent-secondary: #06b6d4;
  --accent-tertiary: #67e8f9;
  --border-color: #bae6fd;
  --shadow: 0 4px 6px -1px rgba(12, 74, 110, 0.1);
  --shadow-lg: 0 20px 25px -5px rgba(12, 74, 110, 0.1);
}

[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-card: #334155;
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --accent-primary: #3b82f6;
  --accent-secondary: #10b981;
  --accent-tertiary: #f59e0b;
  --border-color: #475569;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.3);
}

[data-theme="solarized"] {
  --bg-primary: #fdf6e3;
  --bg-secondary: #eee8d5;
  --bg-card: #fffbf0;
  --text-primary: #657b83;
  --text-secondary: #839496;
  --text-muted: #93a1a1;
  --accent-primary: #268bd2;
  --accent-secondary: #2aa198;
  --accent-tertiary: #b58900;
  --border-color: #d3d0c8;
  --shadow: 0 4px 6px -1px rgba(101, 123, 131, 0.1);
  --shadow-lg: 0 20px 25px -5px rgba(101, 123, 131, 0.1);
}

[data-theme="forest"] {
  --bg-primary: #f0f4f1;
  --bg-secondary: #e8f5e8;
  --bg-card: #ffffff;
  --text-primary: #1b4332;
  --text-secondary: #2d5016;
  --text-muted: #52796f;
  --accent-primary: #2d5016;
  --accent-secondary: #40916c;
  --accent-tertiary: #95d5b2;
  --border-color: #d8f3dc;
  --shadow: 0 4px 6px -1px rgba(45, 80, 22, 0.1);
  --shadow-lg: 0 20px 25px -5px rgba(45, 80, 22, 0.1);
}

[data-theme="light"] {
  --bg-primary: #f5f6f7;
  --bg-secondary: #e9ecef;
  --bg-card: #ffffff;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --accent-primary: #3b82f6;
  --accent-secondary: #10b981;
  --accent-tertiary: #f59e0b;
  --border-color: #e2e8f0;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

[data-theme="neon"] {
  --bg-primary: #0a0a0a;
  --bg-secondary: #1a1a1a;
  --bg-card: #262626;
  --text-primary: #ffffff;
  --text-secondary: #a3a3a3;
  --text-muted: #737373;
  --accent-primary: #ff0080;
  --accent-secondary: #00ff88;
  --accent-tertiary: #ffaa00;
  --border-color: #404040;
  --shadow: 0 4px 6px -1px rgba(255, 0, 128, 0.2);
  --shadow-lg: 0 20px 25px -5px rgba(255, 0, 128, 0.2);
}

/* Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: all 0.3s ease;
}

/* Navigation */
.nav {
  background-color: var(--bg-card);
  border-bottom: 1px solid var(--border-color);
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  box-shadow: var(--shadow);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4rem;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-primary);
  text-decoration: none;
}

.brand-icon {
  font-size: 1.5rem;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 2rem;
  margin: 0;
}

.nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s ease;
  padding: 0.5rem 0;
}

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

.theme-selector select {
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  padding: 0.5rem;
  font-size: 0.875rem;
  cursor: pointer;
  transition: all 0.2s ease;
}

.theme-selector select:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

/* Main Content */
.main {
  padding-top: 4rem;
  min-height: 100vh;
}

.page {
  display: none;
  min-height: calc(100vh - 4rem);
}

.page.active {
  display: block;
}

/* Timer Container */
.timer-container {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - 4rem);
  padding: 7rem 2rem;
}

.timer-card {
  background-color: var(--bg-card);
  border-radius: 1.5rem;
  padding: 3rem;
  box-shadow: var(--shadow-lg);
  text-align: center;
  max-width: 500px;
  width: 100%;
  border: 1px solid var(--border-color);
}

.session-info h2 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.session-counter {
  color: var(--text-secondary);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 1rem;
  font-variant-numeric: tabular-nums;
}

.quick-timer-actions {
  display: flex;
  gap: 0.5rem;
  justify-content: center;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

/* Study Tips Section */
.study-tips-section {
  background-color: var(--bg-secondary);
  padding: 4rem 0;
  margin-top: 6rem;
}

.tips-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

.tips-intro {
  text-align: center;
  margin-bottom: 3rem;
}

.tips-intro h2 {
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
}

.tips-intro p {
  font-size: 1.125rem;
  color: var(--text-secondary);
  line-height: 1.7;
  max-width: 800px;
  margin: 0 auto;
}

.tips-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.tip-card {
  background-color: var(--bg-card);
  border-radius: 1rem;
  padding: 2rem;
  box-shadow: var(--shadow);
  border: 1px solid var(--border-color);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.tip-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.tip-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.tip-card h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.tip-card p {
  color: var(--text-secondary);
  line-height: 1.6;
  margin: 0;
}

.tips-outro {
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.tips-outro p {
  font-size: 1.125rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin: 0;
}

.signature {
  font-style: italic;
  color: var(--text-muted);
  margin-top: 2rem;
}

/* Statistics Page */
.stats-header {
  text-align: center;
  margin-bottom: 3rem;
}

.stats-header p {
  font-size: 1.125rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

.time-filter {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
}

.time-filter label {
  font-weight: 500;
  color: var(--text-primary);
}

.time-filter select {
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  padding: 0.5rem 1rem;
  font-size: 1rem;
  cursor: pointer;
}

.time-filter select:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.stat-card {
  background-color: var(--bg-card);
  border-radius: 1rem;
  padding: 2rem;
  box-shadow: var(--shadow);
  border: 1px solid var(--border-color);
  text-align: center;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.stat-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.stat-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.stat-content h3 {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.stat-value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent-primary);
  margin-bottom: 0.5rem;
  font-variant-numeric: tabular-nums;
}

.stat-label {
  color: var(--text-muted);
  font-size: 0.875rem;
}

.stats-actions {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-top: 2rem;
  flex-wrap: wrap;
}

/* Timer Display */
.timer-display {
  margin: 2rem 0;
}

.time-circle {
  position: relative;
  display: inline-block;
}

.progress-ring {
  transform: rotate(-90deg);
}

.progress-ring-bg,
.progress-ring-fill {
  fill: none;
  stroke-width: 8;
}

.progress-ring-bg {
  stroke: var(--border-color);
}

.progress-ring-fill {
  stroke: var(--accent-primary);
  stroke-linecap: round;
  stroke-dasharray: 754;
  stroke-dashoffset: 754;
  transition: stroke-dashoffset 1s linear;
}

.time-text {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

#timeDisplay {
  font-size: 3rem;
  font-weight: 700;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: 0.75rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  text-decoration: none;
  font-family: inherit;
}

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

.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow);
}

.btn-secondary {
  background-color: var(--accent-secondary);
  color: white;
}

.btn-secondary:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow);
}

.btn-tertiary {
  background-color: var(--bg-secondary);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}

.btn-tertiary:hover {
  background-color: var(--border-color);
  transform: translateY(-1px);
}

.btn-small {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

.btn-mini {
  padding: 0.375rem 0.75rem;
  font-size: 0.75rem;
  font-weight: 500;
}

.timer-controls {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin: 2rem 0;
}

/* Timer Settings */
.timer-settings {
  margin-top: 2rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-color);
}

.setting-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
  cursor: pointer;
  color: var(--text-secondary);
}

.setting-item input[type="checkbox"] {
  width: 1rem;
  height: 1rem;
  accent-color: var(--accent-primary);
}

.sound-settings {
  margin-top: 1rem;
}

.sound-settings label {
  display: block;
  margin-bottom: 0.5rem;
  color: var(--text-secondary);
  font-weight: 500;
}

.sound-controls {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

.sound-controls select {
  flex: 1;
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  padding: 0.5rem;
  font-size: 0.875rem;
}

.sound-controls select:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

/* Content Pages */
.content-container {
  max-width: 800px;
  margin: 0 auto;
  padding: 3rem 2rem;
}

.content h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 2rem;
  color: var(--text-primary);
}

.content h2 {
  font-size: 1.5rem;
  font-weight: 600;
  margin: 2rem 0 1rem 0;
  color: var(--text-primary);
}

.content p {
  margin-bottom: 1rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.content ul,
.content ol {
  margin: 1rem 0 1rem 2rem;
  color: var(--text-secondary);
}

.content li {
  margin-bottom: 0.5rem;
  line-height: 1.6;
}

.content strong {
  color: var(--text-primary);
  font-weight: 600;
}

/* Contact Form */
.contact-form {
  margin-top: 2rem;
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
  font-weight: 500;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  font-size: 1rem;
  font-family: inherit;
  transition: border-color 0.2s ease;
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

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

.success-message {
  background-color: var(--accent-secondary);
  color: white;
  padding: 1rem;
  border-radius: 0.5rem;
  margin-top: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.success-message p {
  margin: 0;
  color: white;
}

/* Responsive Design */
@media (max-width: 768px) {
  .nav-container {
    padding: 0 1rem;
    flex-wrap: wrap;
    height: auto;
    min-height: 4rem;
  }

  .nav-menu {
    flex-wrap: wrap;
    gap: 1rem;
  }

  .timer-card {
    padding: 2rem 1.5rem;
    margin: 1rem;
  }

  #timeDisplay {
    font-size: 2.5rem;
  }

  .timer-controls {
    flex-wrap: wrap;
    gap: 0.75rem;
  }

  .btn {
    padding: 0.625rem 1.25rem;
    font-size: 0.875rem;
  }

  .sound-controls {
    flex-direction: column;
    align-items: stretch;
  }

  .content-container {
    padding: 2rem 1rem;
  }

  .content h1 {
    font-size: 2rem;
  }
}

@media (max-width: 480px) {
  .nav-brand {
    font-size: 1.125rem;
  }

  .timer-card {
    padding: 1.5rem 1rem;
  }

  .time-circle {
    transform: scale(0.8);
  }

  #timeDisplay {
    font-size: 2rem;
  }

  .timer-controls {
    gap: 0.5rem;
  }

  .btn {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
  }

  .content h1 {
    font-size: 1.75rem;
  }

  .content-container {
    padding: 1.5rem 1rem;
  }
}

/* Animation for theme transitions */
* {
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

/* Focus states for accessibility */
.btn:focus,
input:focus,
select:focus,
textarea:focus {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

/* Neon theme glow effects */
[data-theme="neon"] .timer-card {
  box-shadow: 0 0 20px rgba(255, 0, 128, 0.3);
}

[data-theme="neon"] .btn-primary {
  box-shadow: 0 0 10px rgba(255, 0, 128, 0.5);
}

[data-theme="neon"] .progress-ring-fill {
  filter: drop-shadow(0 0 5px var(--accent-primary));
}

/* Settings Panel Styles */
.settings-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

.settings-toggle {
  background-color: var(--bg-secondary);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}

.settings-toggle:hover {
  background-color: var(--border-color);
}

.advanced-settings {
  margin-top: 1.5rem;
  padding: 1.5rem;
  background-color: var(--bg-secondary);
  border-radius: 0.75rem;
  border: 1px solid var(--border-color);
}

.advanced-settings h3 {
  margin: 0 0 1rem 0;
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
}

.settings-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

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

.setting-group label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.setting-group input {
  padding: 0.5rem;
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  background-color: var(--bg-card);
  color: var(--text-primary);
  font-size: 0.875rem;
}

.setting-group input:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.quick-actions h4 {
  margin: 0 0 0.75rem 0;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.action-buttons {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

/* Footer Styles */
.footer {
  background-color: var(--bg-card);
  border-top: 1px solid var(--border-color);
  padding: 2rem 0;
  margin-top: 4rem;
}

.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
  text-align: center;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.footer-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  transition: color 0.2s ease;
}

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

.footer-text {
  color: var(--text-muted);
  font-size: 0.875rem;
}

.footer-text p {
  margin: 0;
}

@media (max-width: 768px) {
  .settings-grid {
    gap: 0.75rem;
  }
  
  .action-buttons {
    flex-direction: column;
  }
  
  .footer-links {
    flex-direction: column;
    gap: 1rem;
  }
  
  .settings-header {
    flex-direction: column;
    gap: 1rem;
    align-items: stretch;
  }
  
  .tips-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
  
  .tips-intro h2 {
    font-size: 1.875rem;
  }
  
  .tips-container {
    padding: 0 1rem;
  }
  
  .study-tips-section {
    padding: 3rem 0;
  }
  
  .quick-timer-actions {
    flex-direction: column;
  }
}