/* -------------------------------------------------------------
 * PREMIUM DARK/GLASSMORPHIC DESIGN SYSTEM & STYLES
 * ------------------------------------------------------------- */

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

:root {
  --bg-color: #0b0f19;
  --bg-gradient: radial-gradient(circle at top right, #111a2e, #070a12);
  --card-bg: rgba(22, 30, 47, 0.75);
  --card-border: rgba(255, 255, 255, 0.07);
  --card-glow: rgba(6, 182, 212, 0.15);
  
  /* Palette Colors */
  --color-primary: #06b6d4;     /* Electric Teal */
  --color-primary-hover: #0891b2;
  --color-secondary: #f59e0b;   /* Amber / Back row */
  --color-secondary-hover: #d97706;
  --color-accent: #10b981;      /* Emerald Green / Valid states */
  --color-danger: #ef4444;      /* Soft Red / Warning states */
  --color-dark-gray: #1e293b;
  --color-light-gray: #334155;
  
  /* Text Colors */
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-dark: #64748b;
  
  /* Typography */
  --font-ui: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  
  /* Shadows & Radius */
  --card-radius: 20px;
  --input-radius: 12px;
  --btn-radius: 12px;
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.3), 0 10px 10px -5px rgba(0, 0, 0, 0.2);
  --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
  background-color: var(--bg-color);
  background-image: var(--bg-gradient);
  color: var(--text-main);
  font-family: var(--font-ui);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 1.5rem;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* App Container */
.app-container {
  width: 100%;
  max-width: 1240px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

/* Header */
.app-header {
  text-align: center;
  margin-bottom: 0.5rem;
}

.logo-area {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
}

.logo-icon {
  width: 32px;
  height: 32px;
  color: var(--color-primary);
  filter: drop-shadow(0 0 8px rgba(6, 182, 212, 0.5));
}

.app-header h1 {
  font-size: 2.25rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  background: linear-gradient(135deg, #ffffff 30%, #a5f3fc 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.subtitle {
  color: var(--text-muted);
  font-size: 1.05rem;
  font-weight: 400;
  max-width: 600px;
  margin: 0 auto;
}

/* Grid Layout */
.calculator-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 1.5rem;
}

/* Cards styling */
.card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--card-radius);
  padding: 1.75rem;
  box-shadow: var(--shadow-lg);
  backdrop-filter: blur(12px);
  position: relative;
  overflow: hidden;
  transition: border-color var(--transition-normal), box-shadow var(--transition-normal);
}

.card:hover {
  border-color: rgba(6, 182, 212, 0.2);
  box-shadow: 0 25px 35px -5px rgba(0, 0, 0, 0.4), var(--card-glow);
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.card-header h2 {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.badge {
  background: rgba(6, 182, 212, 0.1);
  border: 1px solid rgba(6, 182, 212, 0.2);
  color: var(--color-primary);
  padding: 0.35rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 600;
}

.divider {
  border: 0;
  height: 1px;
  background: linear-gradient(to right, transparent, var(--card-border), transparent);
  margin: 1.5rem 0;
}

/* Form inputs & Form Group */
.form-group {
  margin-bottom: 1.25rem;
}

.form-group:last-child {
  margin-bottom: 0;
}

.input-label {
  display: block;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

/* Presets Grid (Block A) */
.presets-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(68px, 1fr));
  gap: 0.5rem;
  max-height: 150px;
  overflow-y: auto;
  padding-right: 0.25rem;
}

/* Scrollbar styling for presets */
.presets-grid::-webkit-scrollbar {
  width: 6px;
}
.presets-grid::-webkit-scrollbar-track {
  background: rgba(0, 0, 0, 0.15);
  border-radius: 3px;
}
.presets-grid::-webkit-scrollbar-thumb {
  background: var(--color-light-gray);
  border-radius: 3px;
}
.presets-grid::-webkit-scrollbar-thumb:hover {
  background: var(--text-dark);
}

.btn-preset {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--card-border);
  border-radius: 8px;
  color: var(--text-main);
  padding: 0.5rem 0.25rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: center;
}

.btn-preset:hover {
  background: rgba(6, 182, 212, 0.1);
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-1px);
}

.btn-preset.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #04080f;
  font-weight: 700;
  box-shadow: 0 0 12px rgba(6, 182, 212, 0.4);
}

/* Width numeric input (Block Б) */
.input-with-unit {
  position: relative;
  display: flex;
  align-items: center;
}

.input-with-unit input {
  width: 100%;
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--card-border);
  border-radius: var(--input-radius);
  color: var(--text-main);
  padding: 0.85rem 3rem 0.85rem 1rem;
  font-family: var(--font-mono);
  font-size: 1.15rem;
  font-weight: 600;
  outline: none;
  transition: all var(--transition-fast);
}

.input-with-unit input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(6, 182, 212, 0.2);
  background: rgba(0, 0, 0, 0.35);
}

.input-with-unit .unit {
  position: absolute;
  right: 1.25rem;
  color: var(--text-dark);
  font-weight: 700;
  font-size: 0.95rem;
  pointer-events: none;
}

.input-helper {
  font-size: 0.75rem;
  color: var(--text-dark);
  margin-top: 0.35rem;
}

/* Increment / Decrement Counter Control */
.counter-control {
  display: flex;
  align-items: center;
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--card-border);
  border-radius: var(--input-radius);
  padding: 0.25rem;
  width: 100%;
}

.btn-counter {
  background: var(--color-light-gray);
  border: none;
  border-radius: 9px;
  width: 42px;
  height: 42px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-main);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-counter:hover {
  background: var(--color-primary);
  color: #04080f;
  transform: scale(1.05);
}

.btn-counter:active {
  transform: scale(0.95);
}

.btn-counter svg {
  width: 16px;
  height: 16px;
}

.counter-control input {
  flex: 1;
  background: transparent;
  border: none;
  text-align: center;
  color: var(--text-main);
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 700;
  width: 100%;
  outline: none;
  -moz-appearance: textfield;
}

.counter-control input::-webkit-outer-spin-button,
.counter-control input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

/* RESULTS PANEL */
.results-panel {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

/* Main Result Card */
.result-card.main-result {
  background: linear-gradient(135deg, rgba(6, 182, 212, 0.15) 0%, rgba(22, 30, 47, 0.8) 100%);
  border: 1px solid rgba(6, 182, 212, 0.25);
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 0 15px rgba(6, 182, 212, 0.1);
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.result-card.main-result:hover {
  border-color: rgba(6, 182, 212, 0.4);
  box-shadow: 0 25px 35px -5px rgba(0, 0, 0, 0.5), 0 0 25px rgba(6, 182, 212, 0.2);
}

.card-glow-effect {
  position: absolute;
  top: -50px;
  right: -50px;
  width: 120px;
  height: 120px;
  background: radial-gradient(circle, rgba(6, 182, 212, 0.3) 0%, transparent 70%);
  filter: blur(10px);
  pointer-events: none;
}

.result-label {
  font-size: 0.9rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-primary);
  margin-bottom: 0.5rem;
}

.result-value-container {
  display: flex;
  align-items: baseline;
  margin-bottom: 0.75rem;
}

.result-value {
  font-family: var(--font-mono);
  font-size: 3.75rem;
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.02em;
  color: #ffffff;
  text-shadow: 0 0 20px rgba(6, 182, 212, 0.3);
}

.result-unit {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-left: 0.5rem;
}

.result-desc {
  font-size: 0.85rem;
  line-height: 1.45;
  color: var(--text-muted);
}

/* Recommendation Card */
.recommendation-card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 1.25rem;
  border-left: 3px solid var(--color-secondary);
  padding-left: 0.75rem;
}

.rec-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
  margin-bottom: 1.25rem;
}

.rec-item {
  background: rgba(0, 0, 0, 0.15);
  border: 1px solid rgba(255, 255, 255, 0.03);
  padding: 1rem;
  border-radius: 12px;
}

.rec-label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 0.25rem;
}

.rec-value {
  font-family: var(--font-mono);
  font-size: 1.45rem;
  font-weight: 700;
  color: var(--text-main);
  display: flex;
  align-items: baseline;
}

.rec-unit {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-left: 0.25rem;
}

.rec-sub {
  font-size: 0.72rem;
  color: var(--text-dark);
  margin-top: 0.25rem;
  line-height: 1.2;
}

/* Warning Alerts */
.status-alert {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  background: rgba(239, 68, 68, 0.1);
  border: 1px solid rgba(239, 68, 68, 0.2);
  border-radius: 12px;
  padding: 0.85rem 1rem;
  color: #fca5a5;
  font-size: 0.82rem;
  line-height: 1.4;
  opacity: 0;
  visibility: hidden;
  height: 0;
  margin-top: 0;
  padding: 0;
  border: 0;
  overflow: hidden;
  transition: all var(--transition-normal);
}

.status-alert.show {
  opacity: 1;
  visibility: visible;
  height: auto;
  margin-top: 0.5rem;
  padding: 0.85rem 1rem;
  border: 1px solid rgba(239, 68, 68, 0.2);
}

.status-alert.good-status {
  background: rgba(16, 185, 129, 0.1);
  border-color: rgba(16, 185, 129, 0.2);
  color: #a7f3d0;
}

.alert-icon {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

/* FULL WIDTH VISUALIZER CARD (Block В) */
.full-width {
  grid-column: 1 / -1;
}

.visualization-header {
  margin-bottom: 1rem;
}

.legend {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-muted);
}

.color-dot {
  width: 10px;
  height: 10px;
  border-radius: 3px;
  display: inline-block;
}

.front-dot {
  background: var(--color-primary);
  box-shadow: 0 0 6px rgba(6, 182, 212, 0.4);
}

.back-dot {
  background: var(--color-secondary);
  box-shadow: 0 0 6px rgba(245, 158, 11, 0.4);
}

.post-dot {
  background: #475569;
}

/* SVG Schematic styling */
.visualizer-container {
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid rgba(255, 255, 255, 0.03);
  border-radius: 12px;
  padding: 1rem;
  margin-bottom: 1rem;
  overflow-x: auto;
}

.svg-wrapper {
  width: 100%;
  min-width: 700px;
}

#schematic-svg {
  width: 100%;
  height: auto;
  display: block;
}

/* SVG Interactivity styling */
#schematic-svg .post {
  fill: #475569;
  stroke: #64748b;
  stroke-width: 1;
  rx: 4px;
}

#schematic-svg .picket-front {
  fill: url(#front-picket-grad);
  stroke: var(--color-primary);
  stroke-width: 1;
  rx: 3px;
  transition: all var(--transition-fast);
  cursor: pointer;
}

#schematic-svg .picket-front:hover {
  filter: drop-shadow(0 0 6px rgba(6, 182, 212, 0.8));
}

#schematic-svg .picket-back {
  fill: url(#back-picket-grad);
  stroke: var(--color-secondary);
  stroke-width: 1;
  rx: 3px;
  transition: all var(--transition-fast);
  cursor: pointer;
}

#schematic-svg .picket-back:hover {
  filter: drop-shadow(0 0 6px rgba(245, 158, 11, 0.8));
}

#schematic-svg .dim-line {
  stroke: #475569;
  stroke-width: 1;
  stroke-dasharray: 2 2;
}

#schematic-svg .dim-solid {
  stroke: #64748b;
  stroke-width: 1;
}

#schematic-svg .dim-arrow {
  fill: #64748b;
}

#schematic-svg .dim-text {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  fill: var(--text-muted);
  text-anchor: middle;
}

#schematic-svg .dim-text.highlight {
  fill: var(--color-primary);
  font-weight: 700;
  font-size: 12px;
}

#schematic-svg .overlap-zone {
  fill: rgba(16, 185, 129, 0.15);
  stroke: var(--color-accent);
  stroke-width: 1;
  stroke-dasharray: 1 1;
  transition: all var(--transition-fast);
}

#schematic-svg .overlap-zone.invalid {
  fill: rgba(239, 68, 68, 0.15);
  stroke: var(--color-danger);
}

#schematic-svg .gap-indicator {
  fill: none;
  stroke: var(--color-primary);
  stroke-width: 1.5;
}

/* Visualizer footer statistics */
.visualizer-controls {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-muted);
  flex-wrap: wrap;
  gap: 0.75rem;
}

.vis-stat strong {
  color: var(--text-main);
}

.vis-stat-divider {
  margin: 0 0.5rem;
  color: var(--color-light-gray);
}

.vis-instruction {
  font-size: 0.8rem;
  color: var(--text-dark);
  font-style: italic;
}

/* FOOTER */
.app-footer {
  text-align: center;
  padding: 1.5rem 0;
  color: var(--text-dark);
  font-size: 0.8rem;
}

/* -------------------------------------------------------------
 * RESPONSIVENESS (MOBILE OPTIMIZATION)
 * ------------------------------------------------------------- */
@media (max-width: 900px) {
  .calculator-grid {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }
}

@media (max-width: 600px) {
  body {
    padding: 1rem 0.75rem;
  }
  
  .app-header h1 {
    font-size: 1.75rem;
  }
  
  .subtitle {
    font-size: 0.9rem;
  }
  
  .card {
    padding: 1.25rem;
    border-radius: 16px;
  }
  
  .presets-grid {
    grid-template-columns: repeat(auto-fill, minmax(62px, 1fr));
  }
  
  .result-value {
    font-size: 3rem;
  }
  
  .rec-grid {
    grid-template-columns: 1fr;
    gap: 0.85rem;
  }
  
  .rec-value {
    font-size: 1.25rem;
  }
  
  .visualizer-controls {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }
  
  .vis-instruction {
    display: none; /* Hide hover prompt on touch screens */
  }
}