/**
 * TibCal Core - Universal Calculator Stylesheet
 * Version: 1.0.0
 * Author: TibCal
 * Description: High-performance, modern, responsive CSS design system for all TibCal calculators.
 */

/* ==========================================================================
   CSS Custom Properties (Theme Design Tokens)
   ========================================================================== */
:root {
  --tc-font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
  --tc-primary: #3b82f6;
  --tc-primary-hover: #2563eb;
  --tc-primary-light: #eff6ff;
  --tc-secondary: #64748b;
  --tc-secondary-hover: #475569;
  --tc-secondary-light: #f8fafc;
  --tc-accent-success: #10b981;
  --tc-accent-warning: #f59e0b;
  --tc-accent-danger: #ef4444;
  --tc-accent-info: #06b6d4;
  
  --tc-bg-main: #f8fafc;
  --tc-card-bg: #ffffff;
  --tc-card-border: #e2e8f0;
  --tc-text-main: #0f172a;
  --tc-text-muted: #64748b;
  --tc-text-light: #94a3b8;

  --tc-radius-sm: 6px;
  --tc-radius-md: 12px;
  --tc-radius-lg: 18px;
  --tc-radius-full: 9999px;

  --tc-shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --tc-shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --tc-shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  
  --tc-transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --tc-focus-ring: 0 0 0 3px rgba(59, 130, 246, 0.35);
}

/* Base Wrapper Reset & Typography */
.calculator-section {
  font-family: var(--tc-font-family);
  color: var(--tc-text-main);
  background-color: transparent;
  line-height: 1.6;
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.5rem 1rem;
  box-sizing: border-box;
}

.calculator-section *,
.calculator-section *::before,
.calculator-section *::after {
  box-sizing: border-box;
}

/* ==========================================================================
   Calculator Main Layout & Cards
   ========================================================================== */
.calculator-card {
  background: var(--tc-card-bg);
  border: 1px solid var(--tc-card-border);
  border-radius: var(--tc-radius-lg);
  box-shadow: var(--tc-shadow-md);
  padding: 2rem;
  margin-bottom: 2rem;
  transition: var(--tc-transition);
}

.calculator-card:hover {
  box-shadow: var(--tc-shadow-lg);
}

/* ==========================================================================
   Form & Input Elements
   ========================================================================== */
.calculator-form {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}

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

.form-group label {
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--tc-text-main);
}

.input-field,
.select-field {
  width: 100%;
  padding: 0.75rem 1rem;
  font-size: 1rem;
  font-family: inherit;
  color: var(--tc-text-main);
  background-color: var(--tc-card-bg);
  border: 1.5px solid var(--tc-card-border);
  border-radius: var(--tc-radius-md);
  transition: var(--tc-transition);
  outline: none;
  appearance: none;
}

.select-field {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%2364748b'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'%3E%3C/path%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 1rem center;
  background-size: 1.25rem;
  padding-right: 2.5rem;
}

.input-field:hover,
.select-field:hover {
  border-color: var(--tc-secondary);
}

.input-field:focus,
.select-field:focus,
.input-field:focus-visible,
.select-field:focus-visible {
  border-color: var(--tc-primary);
  box-shadow: var(--tc-focus-ring);
}

.input-field.tc-error {
  border-color: var(--tc-accent-danger);
  box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.2);
}

.tc-error-msg {
  font-size: 0.85rem;
  color: var(--tc-accent-danger);
  margin-top: 0.25rem;
}

/* ==========================================================================
   Buttons
   ========================================================================== */
.calculate-btn,
.reset-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.85rem 1.75rem;
  font-size: 1rem;
  font-weight: 600;
  font-family: inherit;
  border-radius: var(--tc-radius-md);
  cursor: pointer;
  border: none;
  transition: var(--tc-transition);
  text-decoration: none;
  gap: 0.5rem;
}

.calculate-btn {
  background-color: var(--tc-primary);
  color: #ffffff;
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.25);
}

.calculate-btn:hover {
  background-color: var(--tc-primary-hover);
  box-shadow: 0 6px 16px rgba(59, 130, 246, 0.35);
  transform: translateY(-1px);
}

.calculate-btn:active {
  transform: translateY(0);
}

.calculate-btn:focus-visible {
  box-shadow: var(--tc-focus-ring);
}

.reset-btn {
  background-color: var(--tc-secondary-light);
  color: var(--tc-secondary);
  border: 1px solid var(--tc-card-border);
}

.reset-btn:hover {
  background-color: #e2e8f0;
  color: var(--tc-text-main);
}

.reset-btn:focus-visible {
  box-shadow: var(--tc-focus-ring);
}

/* ==========================================================================
   Results Components
   ========================================================================== */
.results-card {
  background: linear-gradient(135deg, var(--tc-primary-light) 0%, #ffffff 100%);
  border: 1.5px solid rgba(59, 130, 246, 0.2);
  border-radius: var(--tc-radius-lg);
  padding: 2rem;
  margin-top: 1.5rem;
  box-shadow: var(--tc-shadow-md);
}

.result-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.85rem 0;
  border-bottom: 1px dashed var(--tc-card-border);
  font-size: 1rem;
}

.result-item:last-child {
  border-bottom: none;
}

.result-item .label {
  color: var(--tc-text-muted);
  font-weight: 500;
}

.result-item .value {
  font-weight: 700;
  color: var(--tc-text-main);
  font-size: 1.15rem;
}

.quick-summary {
  background-color: var(--tc-card-bg);
  border-left: 4px solid var(--tc-primary);
  padding: 1.25rem 1.5rem;
  border-radius: var(--tc-radius-sm);
  margin-bottom: 1.5rem;
  box-shadow: var(--tc-shadow-sm);
}

.quick-summary p {
  margin: 0;
  font-weight: 500;
  color: var(--tc-text-main);
}

/* ==========================================================================
   Informational & Article Content Sections
   ========================================================================== */
.how-to-use,
.formula-section,
.worked-examples,
.faq-section,
.tips-section,
.mistakes-section,
.advantages-section,
.disadvantages-section,
.history-section,
.glossary-section,
.references-section {
  background-color: var(--tc-card-bg);
  border: 1px solid var(--tc-card-border);
  border-radius: var(--tc-radius-lg);
  padding: 2rem;
  margin-top: 2rem;
  box-shadow: var(--tc-shadow-sm);
}

.how-to-use h2,
.formula-section h2,
.worked-examples h2,
.faq-section h2,
.tips-section h2,
.mistakes-section h2,
.advantages-section h2,
.disadvantages-section h2,
.history-section h2,
.glossary-section h2,
.references-section h2 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-top: 0;
  margin-bottom: 1rem;
  color: var(--tc-text-main);
  border-bottom: 2px solid var(--tc-primary-light);
  padding-bottom: 0.5rem;
}

/* Section Variations */
.formula-section {
  background-color: #faf5ff;
  border-color: #e9d5ff;
}

.tips-section {
  background-color: #f0fdf4;
  border-color: #bbf7d0;
}

.mistakes-section {
  background-color: #fef2f2;
  border-color: #fecaca;
}

.worked-examples {
  background-color: #f0f9ff;
  border-color: #bae6fd;
}

/* ==========================================================================
   Tables & Data Grids (Glossary, Comparisons, Worked Examples)
   ========================================================================== */
.tc-table-wrapper {
  width: 100%;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin: 1.25rem 0;
  border-radius: var(--tc-radius-md);
  border: 1px solid var(--tc-card-border);
  box-shadow: var(--tc-shadow-sm);
}

.calculator-section table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  margin: 1.25rem 0;
  border-radius: var(--tc-radius-md);
  overflow: hidden;
  border: 1px solid var(--tc-card-border);
  background-color: var(--tc-card-bg);
  box-shadow: var(--tc-shadow-sm);
}

.tc-table-wrapper table {
  margin: 0;
  border: none;
  box-shadow: none;
  border-radius: 0;
}

.calculator-section table th,
.calculator-section table td {
  padding: 1rem 1.25rem;
  text-align: left;
  vertical-align: top;
  font-size: 0.95rem;
  line-height: 1.6;
}

.calculator-section table th {
  background-color: #f1f5f9;
  color: var(--tc-text-main);
  font-weight: 700;
  font-size: 0.875rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border-bottom: 2px solid var(--tc-card-border);
}

.calculator-section table td {
  border-bottom: 1px solid var(--tc-card-border);
  color: var(--tc-text-main);
}

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

.calculator-section table tr:nth-child(even) td {
  background-color: rgba(248, 250, 252, 0.65);
}

.calculator-section table tr:hover td {
  background-color: var(--tc-primary-light);
  transition: var(--tc-transition);
}

/* Specific Glossary Styling (Tables & Definition Lists) */
.glossary-section table td:first-child,
.glossary-section table th:first-child {
  font-weight: 600;
  color: var(--tc-text-main);
  width: 30%;
  min-width: 160px;
}

.glossary-section table td:first-child {
  color: var(--tc-primary-hover);
}

.glossary-section dl {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.75rem;
  margin: 1.25rem 0;
}

@media (min-width: 640px) {
  .glossary-section dl {
    grid-template-columns: minmax(180px, 1fr) 2.5fr;
    align-items: start;
    row-gap: 1rem;
  }
}

.glossary-section dt {
  font-weight: 700;
  color: var(--tc-primary-hover);
  padding-top: 0.5rem;
  font-size: 1rem;
}

.glossary-section dd {
  margin: 0;
  padding: 0.5rem 0 0.85rem 0;
  border-bottom: 1px dashed var(--tc-card-border);
  color: var(--tc-text-main);
  font-size: 0.95rem;
  line-height: 1.6;
}

.glossary-section dd:last-of-type {
  border-bottom: none;
}

/* ==========================================================================
   Content Lists & Badges (Advantages, Disadvantages, Tips, References)
   ========================================================================== */
.calculator-section ul,
.calculator-section ol {
  padding-left: 1.5rem;
  margin: 1rem 0;
}

.calculator-section li {
  margin-bottom: 0.6rem;
  color: var(--tc-text-main);
  line-height: 1.6;
}

.advantages-section ul,
.disadvantages-section ul {
  list-style: none;
  padding-left: 0;
}

.advantages-section ul li,
.disadvantages-section ul li {
  position: relative;
  padding-left: 2.25rem;
  margin-bottom: 0.85rem;
}

.advantages-section ul li::before {
  content: "✓";
  position: absolute;
  left: 0;
  top: 0.15rem;
  width: 1.35rem;
  height: 1.35rem;
  background-color: #d1fae5;
  color: var(--tc-accent-success);
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: bold;
}

.disadvantages-section ul li::before {
  content: "✕";
  position: absolute;
  left: 0;
  top: 0.15rem;
  width: 1.35rem;
  height: 1.35rem;
  background-color: #fee2e2;
  color: var(--tc-accent-danger);
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: bold;
}

/* Formula Highlight Box */
.formula-section code,
.formula-section pre,
.tc-formula-box {
  display: block;
  background: #faf5ff;
  border: 1.5px solid #d8b4fe;
  color: #581c87;
  padding: 1.25rem;
  border-radius: var(--tc-radius-md);
  font-family: SFMono-Regular, Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 1.1rem;
  font-weight: 600;
  text-align: center;
  margin: 1.25rem 0;
  overflow-x: auto;
  box-shadow: var(--tc-shadow-sm);
}

/* References Links */
.references-section ul {
  list-style-type: disc;
  color: var(--tc-text-muted);
}

.references-section a {
  color: var(--tc-primary);
  text-decoration: none;
  font-weight: 500;
  transition: var(--tc-transition);
}

.references-section a:hover {
  text-decoration: underline;
  color: var(--tc-primary-hover);
}

/* FAQ Details/Summary styling */
.faq-section details {
  border-bottom: 1px solid var(--tc-card-border);
  padding: 0.85rem 0;
}

.faq-section details:last-child {
  border-bottom: none;
}

.faq-section summary {
  font-weight: 600;
  cursor: pointer;
  outline: none;
  font-size: 1.05rem;
}

.faq-section summary:focus-visible {
  color: var(--tc-primary);
}

.faq-section details p {
  margin-top: 0.5rem;
  color: var(--tc-text-muted);
}

/* ==========================================================================
   Responsive Breakpoints
   ========================================================================== */
@media (min-width: 768px) {
  .calculator-form.tc-grid-2 {
    grid-template-columns: repeat(2, 1fr);
  }

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

@media (max-width: 767px) {
  .calculator-card,
  .results-card,
  .how-to-use,
  .formula-section,
  .worked-examples,
  .faq-section,
  .tips-section,
  .mistakes-section,
  .advantages-section,
  .disadvantages-section,
  .history-section,
  .glossary-section,
  .references-section {
    padding: 1.25rem;
    border-radius: var(--tc-radius-md);
  }

  .calculate-btn,
  .reset-btn {
    width: 100%;
  }

  .calculator-section table th,
  .calculator-section table td {
    padding: 0.75rem 0.85rem;
    font-size: 0.875rem;
  }
}