/* Slide Rule Design System inspired by akshatnigam.com */
@import url('https://fonts.googleapis.com/css2?family=Open+Sans:wght@300;400;500;600;700;800&family=Fira+Code:wght@500;700&display=swap');

:root {
  /* Light Theme Defaults (akshatnigam.com) */
  --bg-primary: #ffffff;
  --bg-card: #f8fafc;
  --bg-card-hover: #e0e7ff;
  --bg-card-border: #e5e7eb;
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;
  
  --accent-blue: #2563eb;
  --accent-blue-hover: #1d4ed8;
  --accent-blue-light: #60a5fa;
  --accent-indigo: #4f46e5;
  --accent-emerald: #10b981;
  --accent-amber: #d97706;
  --accent-rose: #dc2626;

  --ruler-body: #fffefb;
  --ruler-slider: #fefce8;
  --ruler-text: #1f2937;
  --ruler-hairline: #dc2626;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  
  --font-sans: 'Open Sans', system-ui, -apple-system, sans-serif;
  --font-mono: 'Fira Code', monospace;
}

[data-theme="dark"], body.dark-mode {
  /* Dark Theme Palette (akshatnigam.com) */
  --bg-primary: #111827;
  --bg-card: #1f2937;
  --bg-card-hover: #374151;
  --bg-card-border: #374151;
  --text-primary: #f9fafb;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;
  
  --accent-blue: #3b82f6;
  --accent-blue-hover: #60a5fa;
  --ruler-body: #fdfbf7;
  --ruler-slider: #fefcd8;
  --ruler-text: #111827;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Tool Container & Header (consistent with akshatnigam.com) */
.tool-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 0.5rem;
}

.back-link {
  display: inline-block;
  color: var(--accent-blue);
  text-decoration: none;
  font-weight: 600;
  margin-bottom: 1.5rem;
  transition: all 0.3s ease;
}

.back-link:hover {
  color: var(--accent-blue-hover);
  transform: translateX(-4px);
}

.tool-header {
  text-align: center;
  margin-bottom: 2rem;
}

.tool-title {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.tool-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
}

.dark-mode-toggle {
  position: fixed;
  top: 20px;
  right: 20px;
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.5rem;
  color: var(--text-secondary);
  transition: all 0.3s ease;
  z-index: 1000;
  padding: 0.5rem;
}

.dark-mode-toggle:hover {
  color: var(--accent-blue);
  transform: scale(1.1);
}

/* Toolbar */
.toolbar {
  max-width: 1200px;
  margin: 1.5rem auto 1rem;
  padding: 0 1.5rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.tool-group {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.btn {
  background: var(--bg-card);
  border: 1px solid var(--bg-card-border);
  color: var(--text-primary);
  padding: 0.55rem 1rem;
  border-radius: 0.375rem;
  font-size: 0.875rem;
  font-weight: 600;
  font-family: var(--font-sans);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  transition: all 0.2s ease;
}

.btn:hover {
  border-color: var(--accent-blue);
  color: var(--accent-blue);
  background: var(--bg-card-hover);
}

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

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

select.btn {
  appearance: none;
  padding-right: 2.25rem;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%232563eb'%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 0.75rem center;
  background-size: 1rem;
}

/* Digital Readout Inspector */
.readout-panel {
  max-width: 1200px;
  margin: 0 auto 1.5rem;
  padding: 0 1.5rem;
}

.readout-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 0.75rem;
  background: var(--bg-card);
  border: 1px solid var(--bg-card-border);
  padding: 1rem;
  border-radius: 0.5rem;
  box-shadow: var(--shadow-md);
}

.readout-card {
  background: var(--bg-primary);
  border: 1px solid var(--bg-card-border);
  padding: 0.6rem 0.8rem;
  border-radius: 0.375rem;
  text-align: center;
}

.readout-label {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent-blue);
  margin-bottom: 0.2rem;
}

.readout-val {
  font-family: var(--font-mono);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
}

/* Slide Rule Canvas Container */
.slide-rule-workspace {
  max-width: 1200px;
  margin: 0 auto 2rem;
  padding: 0 1.5rem;
  position: relative;
}

.ruler-container {
  background: var(--ruler-body);
  border-radius: 8px;
  border: 1px solid var(--bg-card-border);
  box-shadow: var(--shadow-lg);
  padding: 2.5rem 1.5rem;
  position: relative;
  overflow: hidden;
  user-select: none;
  cursor: grab;
}

.ruler-container:active {
  cursor: grabbing;
}

#slideRuleCanvas {
  width: 100%;
  height: 520px;
  display: block;
}

/* Guide Container */
.guide-container {
  max-width: 900px;
  margin: 2rem auto;
  padding: 0 1.5rem;
}

.guide-hero {
  text-align: center;
  padding: 2rem 1rem 2rem;
}

.guide-title {
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.guide-title span {
  color: var(--accent-blue);
}

.guide-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--bg-card-border);
  border-radius: 0.5rem;
  padding: 2rem;
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow-md);
}

.card-title {
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--accent-blue);
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.step-box {
  background: var(--bg-primary);
  border-left: 4px solid var(--accent-blue);
  padding: 1rem 1.25rem;
  border-radius: 0 0.375rem 0.375rem 0;
  margin: 1rem 0;
}

.step-box ol, .step-box ul {
  padding-left: 1.25rem;
  margin-top: 0.5rem;
}

.math-formula {
  background: var(--bg-primary);
  font-family: var(--font-mono);
  padding: 0.75rem 1rem;
  border-radius: 0.375rem;
  margin: 0.75rem 0;
  overflow-x: auto;
  color: var(--accent-blue);
  border: 1px solid var(--bg-card-border);
}

.interactive-demo-btn {
  margin-top: 0.75rem;
  background: var(--accent-blue);
  color: #ffffff;
  border: none;
  padding: 0.5rem 1rem;
  border-radius: 0.375rem;
  font-weight: 600;
  font-size: 0.85rem;
  text-decoration: none;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  transition: background-color 0.2s ease;
}

.interactive-demo-btn:hover {
  background: var(--accent-blue-hover);
}

/* Tab Bar */
.tab-bar {
  display: flex;
  gap: 0.5rem;
  border-bottom: 1px solid var(--bg-card-border);
  margin-bottom: 2rem;
}

.tab-item {
  padding: 0.75rem 1.25rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all 0.2s ease;
}

.tab-item:hover {
  color: var(--accent-blue);
}

.tab-item.active {
  color: var(--accent-blue);
  border-bottom-color: var(--accent-blue);
}

@media (max-width: 768px) {
  .tool-container {
    padding: 1.5rem 1rem 0.5rem;
  }
  .tool-title {
    font-size: 2rem;
  }
  .tool-subtitle {
    font-size: 1rem;
  }
  .dark-mode-toggle {
    position: absolute;
    top: 1.5rem;
    right: 1rem;
  }
  .toolbar {
    flex-direction: column;
    align-items: stretch;
  }
}