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

:root {
  --primary-color: #2563eb;
  --primary-hover: #1d4ed8;
  --secondary-color: #64748b;
  --background: #f8fafc;
  --surface: #ffffff;
  --text: #1e293b;
  --text-light: #64748b;
  --border: #e2e8f0;
  --success: #10b981;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 4px 6px rgba(0, 0, 0, 0.1);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background-color: var(--background);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 1rem;
}

/* Header */
.header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

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

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

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.header-nav {
  display: flex;
  gap: 1rem;
}

.header-link {
  color: var(--text);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  transition: all 0.2s;
}

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

/* Main Content */
.main {
  flex: 1;
  padding: 2rem 0;
}

/* Footer */
.footer {
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding: 1.5rem 0;
  text-align: center;
  color: var(--text-light);
  font-size: 0.875rem;
}

/* Typography */
h1 {
  font-size: 1.75rem;
  margin-bottom: 1rem;
  color: var(--text);
}

h2 {
  font-size: 1.25rem;
  margin-bottom: 0.75rem;
  color: var(--text);
}

.intro {
  color: var(--text-light);
  margin-bottom: 2rem;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.625rem 1.25rem;
  border-radius: var(--radius);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.875rem;
  cursor: pointer;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  transition: all 0.2s;
}

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

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

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

/* Result Card */
.result-card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.result-grid {
  display: grid;
  gap: 1rem;
}

.result-item {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 0.75rem;
  border-radius: var(--radius);
  background: var(--background);
}

.result-item.highlight {
  background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
  border: 1px solid #bfdbfe;
}

.result-item .label {
  font-size: 0.75rem;
  color: var(--text-light);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.result-item .value {
  font-size: 1rem;
  color: var(--text);
}

.result-item .value.large {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--primary-color);
}

.result-item .value.mono {
  font-family: 'SF Mono', Monaco, 'Courier New', monospace;
}

.result-item .value.italic {
  font-style: italic;
}

/* Date Form */
.date-picker-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 2rem;
}

.date-form .form-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-bottom: 1rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

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

.form-group select {
  padding: 0.625rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-size: 1rem;
  background: var(--surface);
  cursor: pointer;
}

.form-group select:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* Sample Dates */
.sample-dates {
  margin-bottom: 2rem;
}

.date-list {
  list-style: none;
}

.date-list li {
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--border);
}

.date-list li:last-child {
  border-bottom: none;
}

.date-list a {
  color: var(--text);
  text-decoration: none;
}

.date-list a:hover {
  color: var(--primary-color);
}

/* Tools Section */
.tools-section {
  margin-bottom: 2rem;
}

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 1rem;
}

.tool-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  padding: 1.25rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  transition: all 0.2s;
}

.tool-card:hover {
  border-color: var(--primary-color);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.tool-icon {
  font-size: 2rem;
}

.tool-name {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text);
}

/* Month Grid */
.browse-months {
  margin-top: 2rem;
}

.year-selector {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.year-selector label {
  font-size: 0.875rem;
  color: var(--text-light);
}

.year-selector select {
  padding: 0.5rem 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  font-size: 1rem;
  cursor: pointer;
}

.year-selector select:focus {
  outline: none;
  border-color: var(--primary-color);
}

.view-all-link {
  margin-left: auto;
  font-size: 0.875rem;
  color: var(--primary-color);
  text-decoration: none;
}

.view-all-link:hover {
  text-decoration: underline;
}

.month-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  gap: 0.75rem;
}

.month-link {
  padding: 0.75rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--text);
  text-align: center;
  font-size: 0.875rem;
  transition: all 0.2s;
}

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

/* Month Page */
.month-page .subtitle {
  color: var(--text-light);
  margin-bottom: 1rem;
}

.month-header {
  margin-bottom: 1.5rem;
}

.month-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.month-nav-btn {
  flex: 1;
  text-align: center;
  max-width: 200px;
}

.month-nav-btn.disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

.month-info-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.month-info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
}

.info-item {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.info-label {
  font-size: 0.75rem;
  color: var(--text-light);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.info-value {
  font-size: 1rem;
  color: var(--text);
  font-weight: 500;
}

.month-description {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.month-description p {
  line-height: 1.7;
  color: var(--text);
}

.month-calendar {
  max-width: 100%;
}

.dates-list-section {
  margin-bottom: 1.5rem;
}

.dates-list-section h2 {
  margin-bottom: 1rem;
}

/* Calendar Grid */
.calendar-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
  gap: 0.75rem;
}

.date-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--text);
  transition: all 0.2s;
}

.date-card:hover {
  border-color: var(--primary-color);
  box-shadow: var(--shadow-lg);
}

.date-card .day-num {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
}

.date-card .day-name {
  font-size: 0.75rem;
  color: var(--text-light);
}

/* Formats Table */
.formats-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.table-wrapper {
  overflow-x: auto;
}

.formats-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}

.formats-table th,
.formats-table td {
  padding: 0.75rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.formats-table th {
  background: var(--background);
  font-weight: 600;
  color: var(--text);
}

.formats-table td {
  color: var(--text);
}

.formats-table td.example {
  font-family: 'SF Mono', Monaco, 'Courier New', monospace;
  color: var(--primary-color);
  font-weight: 500;
}

.formats-table code {
  font-size: 0.75rem;
  color: var(--text-light);
  background: var(--background);
  padding: 0.125rem 0.375rem;
  border-radius: 4px;
}

.formats-table tr:last-child td {
  border-bottom: none;
}

.formats-table tr:hover {
  background: var(--background);
}

/* Copy Button */
.btn-copy {
  padding: 0.375rem 0.75rem;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--primary-color);
  background: transparent;
  border: 1px solid var(--primary-color);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.2s;
  white-space: nowrap;
}

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

.btn-copy.copied {
  background: var(--success);
  border-color: var(--success);
  color: white;
}

.copy-text {
  user-select: all;
}

/* Mini Calendar */
.calendar-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.mini-calendar {
  max-width: 350px;
}

.calendar-header {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 0.25rem;
  margin-bottom: 0.5rem;
}

.calendar-header .day-header {
  text-align: center;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-light);
  padding: 0.5rem 0;
}

.calendar-body {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.calendar-week {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 0.25rem;
}

.calendar-cell {
  display: flex;
  align-items: center;
  justify-content: center;
  aspect-ratio: 1;
  font-size: 0.875rem;
  text-decoration: none;
  color: var(--text);
  border-radius: var(--radius);
  transition: all 0.2s;
}

.calendar-cell.empty {
  background: transparent;
}

.calendar-cell:not(.empty):not(.current) {
  background: var(--background);
}

.calendar-cell:not(.empty):not(.current):hover {
  background: var(--primary-color);
  color: white;
}

.calendar-cell.current {
  background: var(--primary-color);
  color: white;
  font-weight: 700;
  box-shadow: 0 2px 4px rgba(37, 99, 235, 0.3);
}

/* FAQ Section */
.faq-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.faq-item summary {
  padding: 1rem;
  cursor: pointer;
  font-weight: 500;
  background: var(--background);
  list-style: none;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::before {
  content: "+";
  margin-right: 0.75rem;
  font-weight: 700;
  color: var(--primary-color);
}

.faq-item[open] summary::before {
  content: "−";
}

.faq-item p {
  padding: 1rem;
  margin: 0;
  border-top: 1px solid var(--border);
  line-height: 1.7;
}

/* Breadcrumb */
.breadcrumb {
  margin-bottom: 1rem;
}

.breadcrumb ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  font-size: 0.875rem;
}

.breadcrumb li {
  display: flex;
  align-items: center;
}

.breadcrumb li:not(:last-child)::after {
  content: "›";
  margin-left: 0.5rem;
  color: var(--text-light);
}

.breadcrumb a {
  color: var(--primary-color);
  text-decoration: none;
}

.breadcrumb a:hover {
  text-decoration: underline;
}

.breadcrumb li[aria-current="page"] {
  color: var(--text-light);
}

/* Nav Links */
.nav-links {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}

/* Birthday Page */
.birthday-page {
  max-width: 100%;
}

.birthday-page h1 {
  text-align: center;
  margin-bottom: 0.5rem;
}

.birthday-page .intro {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 2rem;
}

.birthday-form-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 2rem;
}

.birthday-form .form-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.btn-lg {
  padding: 0.875rem 2rem;
  font-size: 1rem;
  width: 100%;
}

.birthday-result {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 2rem;
}

.birthday-result h2 {
  text-align: center;
  margin-bottom: 1.5rem;
}

.birthday-result .result-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.sentences-section {
  border-top: 1px solid var(--border);
  padding-top: 1.5rem;
  margin-top: 1.5rem;
}

.sentences-section h3 {
  margin-bottom: 1rem;
  font-size: 1.1rem;
}

.sentences-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.sentence-item {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 1rem;
  background: var(--background);
  border-radius: var(--radius);
}

.sentence-th {
  font-size: 0.875rem;
  color: var(--text-light);
}

.sentence-en {
  font-size: 1rem;
  color: var(--text);
  font-weight: 500;
}

.content-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.content-section h2 {
  margin-bottom: 1rem;
}

.content-block {
  margin-bottom: 1.5rem;
}

.content-block:last-child {
  margin-bottom: 0;
}

.content-block h3 {
  font-size: 1rem;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.content-block p {
  line-height: 1.7;
  color: var(--text);
}

/* Anniversary Grid */
.anniversary-list-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.anniversary-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 1rem;
}

.anniversary-item {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 1rem;
  background: var(--background);
  border-radius: var(--radius);
  text-align: center;
}

.anniversary-year {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--primary-color);
}

.anniversary-name {
  font-size: 0.875rem;
  color: var(--text);
  font-weight: 500;
}

.anniversary-name-th {
  font-size: 0.75rem;
  color: var(--text-light);
}

/* Holidays Table */
.holidays-page {
  max-width: 100%;
}

.holidays-page h1 {
  text-align: center;
  margin-bottom: 0.5rem;
}

.holidays-page .intro {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 2rem;
}

.holidays-list-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.holidays-table-wrapper {
  overflow-x: auto;
}

.holidays-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}

.holidays-table th,
.holidays-table td {
  padding: 0.75rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.holidays-table th {
  background: var(--background);
  font-weight: 600;
  color: var(--text);
  white-space: nowrap;
}

.holidays-table td.holiday-en {
  font-weight: 500;
  color: var(--primary-color);
}

.holidays-table td.holiday-desc {
  font-size: 0.8rem;
  color: var(--text-light);
}

.holidays-table tr:hover {
  background: var(--background);
}

/* Calculator Page */
.calculator-page {
  max-width: 100%;
}

.calculator-page h1 {
  text-align: center;
  margin-bottom: 0.5rem;
}

.calculator-page .intro {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 2rem;
}

.calculator-tabs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.tab-btn {
  flex: 1;
  padding: 0.75rem 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
}

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

.tab-btn.active {
  background: var(--primary-color);
  color: white;
  border-color: var(--primary-color);
}

.calculator-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.calculator-form .form-row {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin-bottom: 1rem;
}

.calculator-form input[type="date"],
.calculator-form input[type="number"] {
  padding: 0.625rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-size: 1rem;
  background: var(--surface);
}

.calculator-form input:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.quick-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1rem;
  align-items: center;
}

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

.btn-quick {
  padding: 0.375rem 0.75rem;
  font-size: 0.75rem;
}

.calculator-result {
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

/* Today Page */
.today-page {
  max-width: 100%;
}

.today-page h1 {
  text-align: center;
  margin-bottom: 0.5rem;
}

.today-page .intro {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 2rem;
}

.today-hero {
  background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
  border-radius: var(--radius);
  padding: 2rem;
  margin-bottom: 2rem;
  text-align: center;
}

.today-date-display {
  color: white;
}

.today-thai {
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
  opacity: 0.9;
}

.today-english {
  font-size: 1.75rem;
  font-weight: 700;
}

.today-formats-section {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.today-formats-section h2 {
  margin-bottom: 1rem;
}

/* All Months Page */
.all-months-page {
  max-width: 100%;
}

.all-months-page h1 {
  text-align: center;
  margin-bottom: 0.5rem;
}

.all-months-page .intro {
  text-align: center;
  max-width: 600px;
  margin: 0 auto 2rem;
}

.years-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.year-group {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.year-group[open] {
  box-shadow: var(--shadow);
}

.year-header {
  padding: 1rem 1.25rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  background: var(--surface);
  transition: background 0.2s;
}

.year-header:hover {
  background: var(--background);
}

.year-label {
  font-size: 1.1rem;
  color: var(--text);
}

.year-gregorian {
  font-size: 0.875rem;
  color: var(--text-light);
  font-weight: 400;
}

.months-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  background: var(--background);
  border-top: 1px solid var(--border);
}

.month-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
  padding: 0.75rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  transition: all 0.2s;
}

.month-card:hover {
  border-color: var(--primary-color);
  box-shadow: var(--shadow);
}

.month-name {
  font-weight: 500;
  color: var(--text);
}

.month-english {
  font-size: 0.75rem;
  color: var(--text-light);
}

/* Responsive */
@media (max-width: 640px) {
  h1 {
    font-size: 1.5rem;
  }

  .date-form .form-row {
    grid-template-columns: 1fr;
  }

  .tools-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .month-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .calendar-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .birthday-form .form-row {
    grid-template-columns: 1fr;
  }

  .birthday-result .result-grid {
    grid-template-columns: 1fr;
  }

  .calculator-form .form-row {
    grid-template-columns: 1fr;
  }

  .anniversary-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .tab-btn {
    font-size: 0.75rem;
    padding: 0.5rem;
  }

  .months-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}