/* Reset and base styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary: #667eea;
  --primary-dark: #5a67d8;
  --primary-light: #7c8ff0;
  --success: #48bb78;
  --warning: #f56565;
  --info: #4299e1;
  --bg-dark: #1a202c;
  --bg-darker: #0f1419;
  --bg-card: rgba(45, 55, 72, 0.95);
  --text-primary: #e2e8f0;
  --text-secondary: #a0aec0;
  --text-muted: #718096;
  --border: rgba(255, 255, 255, 0.1);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', 'Roboto', 'Helvetica Neue', 'Arial', sans-serif;
  background: linear-gradient(135deg, #0f0f23 0%, #1a1a3e 50%, #16213e 100%);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  width: 100%;
}

body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-image:
    radial-gradient(circle at 20% 80%, rgba(102, 126, 234, 0.1) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(72, 187, 120, 0.1) 0%, transparent 50%),
    radial-gradient(circle at 40% 40%, rgba(66, 153, 225, 0.1) 0%, transparent 50%);
  pointer-events: none;
  z-index: 1;
}

.app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  position: relative;
  z-index: 2;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
  width: 100%;
  overflow-x: hidden;
}

@media (min-width: 768px) {
  .container {
    padding: 0 1.5rem;
  }
}

/* Header */
.header {
  background: linear-gradient(180deg, rgba(26, 26, 46, 0.8) 0%, rgba(26, 26, 46, 0.4) 100%);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: 2.5rem 0;
  text-align: center;
  position: relative;
}

.header::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100px;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--primary), transparent);
}

.header h1 {
  font-size: 3rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 1.15rem;
  font-weight: 400;
  opacity: 0.9;
}

/* Main content */
.main {
  flex: 1;
  padding: 3rem 0;
}

.main .container {
  display: flex;
  flex-direction: column;
  gap: 2rem;
  max-width: 100%;
  overflow-x: hidden;
}

.main-content {
  width: 100%;
  min-width: 0;
}

/* Cards */
.calculator-card,
.reference-card,
.guide-card {
  background: var(--bg-card);
  backdrop-filter: blur(20px);
  border-radius: 20px;
  padding: 1.5rem;
  margin-bottom: 2rem;
  box-shadow:
    0 10px 40px rgba(0, 0, 0, 0.4),
    inset 0 1px 0 rgba(255, 255, 255, 0.1);
  border: 1px solid var(--border);
  position: relative;
  overflow: visible;
}

@media (min-width: 768px) {

  .calculator-card,
  .reference-card,
  .guide-card {
    padding: 2rem;
  }
}

@media (min-width: 1024px) {

  .calculator-card,
  .reference-card,
  .guide-card {
    padding: 2.5rem;
  }
}

.calculator-card::before,
.reference-card::before,
.guide-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.1), transparent);
}

.reference-card h3,
.guide-card h3 {
  color: var(--text-primary);
  margin-bottom: 1.75rem;
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}

/* Guide card */
.guide-card {
  background: rgba(45, 55, 72, 0.95);
  backdrop-filter: blur(10px);
  border-radius: 16px;
  padding: 2rem;
  margin-bottom: 2rem;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.guide-card h3 {
  color: #e2e8f0;
  margin-bottom: 1rem;
  font-size: 1.25rem;
  font-weight: 600;
}

.guide .guide-item {
  background: #2d3748;
  border: 1px solid #4a5568;
  border-radius: 8px;
  margin: 0.75rem 0;
  overflow: hidden;
}

.guide .guide-item>summary {
  cursor: pointer;
  list-style: none;
  padding: 0.9rem 1rem;
  color: #e2e8f0;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.guide .guide-item[open]>summary {
  background: #1a202c;
}

.guide .guide-content {
  padding: 1rem 1.25rem 1.25rem;
  color: #a0aec0;
}

.guide .guide-content ul {
  margin-left: 1rem;
}

.guide .guide-content li {
  margin: 0.35rem 0;
}

/* Input groups */
.input-group {
  margin-bottom: 2rem;
}

.input-group small {
  display: block;
  margin-top: 0.5rem;
  color: var(--text-muted);
  font-size: 0.85rem;
  line-height: 1.4;
}

.input-group label {
  display: block;
  margin-bottom: 0.75rem;
  font-weight: 500;
  color: var(--text-secondary);
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.input-group label::before {
  content: '';
  display: inline-block;
  width: 3px;
  height: 14px;
  background: var(--primary);
  border-radius: 2px;
  flex-shrink: 0;
}

.input-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.input-wrapper input,
.input-group input[type="number"] {
  flex: 1;
  padding: 1rem 1.25rem;
  border: 2px solid transparent;
  border-radius: 12px;
  font-size: 1rem;
  background: rgba(26, 32, 44, 0.8);
  color: var(--text-primary);
  transition: all 0.3s ease;
  font-weight: 400;
  font-family: inherit;
}

.input-wrapper input:hover,
.input-group input[type="number"]:hover {
  background: rgba(26, 32, 44, 1);
  border-color: rgba(102, 126, 234, 0.3);
}

.input-wrapper input:focus,
.input-group input[type="number"]:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow:
    0 0 0 4px rgba(102, 126, 234, 0.1),
    0 4px 12px rgba(102, 126, 234, 0.2);
  background: rgba(26, 32, 44, 1);
}

.unit {
  position: absolute;
  right: 1.25rem;
  color: var(--text-muted);
  font-weight: 600;
  pointer-events: none;
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Select wrapper */
.select-wrapper {
  position: relative;
}

.select-wrapper select {
  width: 100%;
  padding: 1rem 1.25rem;
  padding-right: 3rem;
  border: 2px solid transparent;
  border-radius: 12px;
  font-size: 1.05rem;
  background: rgba(26, 32, 44, 0.8);
  color: var(--text-primary);
  appearance: none;
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 500;
}

.select-wrapper::after {
  content: '▼';
  position: absolute;
  right: 1.25rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
  font-size: 0.75rem;
  transition: transform 0.3s ease;
}

.select-wrapper:hover select {
  background: rgba(26, 32, 44, 1);
  border-color: rgba(102, 126, 234, 0.3);
}

.select-wrapper select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow:
    0 0 0 4px rgba(102, 126, 234, 0.1),
    0 4px 12px rgba(102, 126, 234, 0.2);
  background: rgba(26, 32, 44, 1);
}

.select-wrapper select:focus~ ::after {
  transform: translateY(-50%) rotate(180deg);
}

/* Battery section */
.battery-section {
  margin: 2rem 0;
  padding: 1.5rem;
  background: rgba(26, 32, 44, 0.5);
  border-radius: 16px;
  border: 1px solid var(--border);
}

@media (min-width: 768px) {
  .battery-section {
    padding: 2rem;
  }
}

.battery-container {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 3rem;
  flex-wrap: wrap;
}

.battery {
  position: relative;
  width: 180px;
  height: 80px;
  border: 4px solid #4a5568;
  border-radius: 12px;
  background: linear-gradient(180deg, #1a202c 0%, #0f1419 100%);
  overflow: hidden;
  box-shadow:
    inset 0 2px 4px rgba(0, 0, 0, 0.5),
    0 4px 12px rgba(0, 0, 0, 0.3);
}

.battery-terminal {
  position: absolute;
  right: -10px;
  top: 50%;
  transform: translateY(-50%);
  width: 8px;
  height: 24px;
  background: #4a5568;
  border-radius: 0 4px 4px 0;
  box-shadow: 2px 0 4px rgba(0, 0, 0, 0.3);
}

.battery-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, #ff6b6b, #4ecdc4);
  transition: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  box-shadow: inset 0 0 20px rgba(255, 255, 255, 0.1);
}

.battery-fill span {
  color: white;
  font-weight: 800;
  font-size: 1.4rem;
  text-shadow:
    0 2px 4px rgba(0, 0, 0, 0.4),
    0 0 20px rgba(255, 255, 255, 0.2);
  z-index: 1;
  letter-spacing: -0.02em;
}

.battery-info {
  text-align: center;
}

.voltage-display {
  font-size: 1.5rem;
  font-weight: 700;
  color: #e2e8f0;
  margin-bottom: 0.5rem;
}

.status-text {
  color: #a0aec0;
  font-size: 0.9rem;
}

/* Advanced section */
.advanced-section {
  margin: 2rem 0;
}

.advanced-toggle {
  width: 100%;
  padding: 1.25rem;
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(102, 126, 234, 0.05) 100%);
  border: 2px solid rgba(102, 126, 234, 0.3);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  cursor: pointer;
  transition: all 0.3s ease;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  position: relative;
  overflow: hidden;
}

.advanced-toggle::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.1), transparent);
  transition: left 0.5s ease;
}

.advanced-toggle:hover::before {
  left: 100%;
}

.advanced-toggle:hover {
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.2) 0%, rgba(102, 126, 234, 0.1) 100%);
  border-color: var(--primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(102, 126, 234, 0.3);
}

.advanced-toggle.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
  box-shadow: 0 4px 20px rgba(102, 126, 234, 0.4);
}

.toggle-arrow {
  transition: transform 0.2s ease;
}

.advanced-toggle.active .toggle-arrow {
  transform: rotate(180deg);
}

.advanced-panel {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

.advanced-panel.open {
  max-height: 500px;
}

.advanced-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-top: 1rem;
  padding: 1rem;
  background: #2d3748;
  border-radius: 8px;
  border: 1px solid #4a5568;
}

@media (min-width: 640px) {
  .advanced-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Tips section */
.tips-section {
  margin: 2rem 0;
}

.tip-card {
  display: flex;
  align-items: flex-start;
  gap: 1.25rem;
  padding: 1.5rem;
  border-radius: 12px;
  background: linear-gradient(135deg, rgba(45, 55, 72, 0.8) 0%, rgba(26, 32, 44, 0.8) 100%);
  border-left: 4px solid var(--primary);
  position: relative;
  overflow: hidden;
  transition: all 0.3s ease;
}

.tip-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(90deg, rgba(102, 126, 234, 0.1) 0%, transparent 50%);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.tip-card:hover::before {
  opacity: 1;
}

.tip-icon {
  font-size: 1.75rem;
  flex-shrink: 0;
  animation: pulse 2s infinite;
}

@keyframes pulse {

  0%,
  100% {
    transform: scale(1);
  }

  50% {
    transform: scale(1.05);
  }
}

.tip-content {
  flex: 1;
}

.tip-title {
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  font-size: 1.1rem;
  letter-spacing: -0.01em;
}

.tip-text {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.6;
}

/* Reference grid */
.reference-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1rem;
}

.reference-item {
  background: #2d3748;
  padding: 1rem;
  border-radius: 8px;
  text-align: center;
  border: 1px solid #4a5568;
}

.reference-voltage {
  font-size: 1.1rem;
  font-weight: 600;
  color: #e2e8f0;
  margin-bottom: 0.25rem;
}

.reference-percent {
  font-size: 0.9rem;
  color: #a0aec0;
}

.reference-item.current-voltage {
  background: rgba(102, 126, 234, 0.2);
  border-color: #667eea;
  box-shadow: 0 0 0 2px rgba(102, 126, 234, 0.3);
}

.reference-item.current-voltage .reference-voltage {
  color: #667eea;
  font-weight: 700;
}

.reference-item.current-voltage .reference-percent {
  color: #667eea;
  font-weight: 600;
}

/* Responsive design */
@media (max-width: 768px) {
  .container {
    padding: 0 1rem;
  }

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

  .calculator-card,
  .reference-card {
    padding: 1.5rem;
  }

  .battery-container {
    flex-direction: column;
    gap: 1rem;
  }

  .advanced-grid {
    grid-template-columns: 1fr;
  }

  .reference-grid {
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  }
}

@media (max-width: 480px) {
  .header {
    padding: 1.5rem 0;
  }

  .main {
    padding: 1rem 0;
  }

  .calculator-card,
  .reference-card {
    padding: 1rem;
  }

  .battery {
    width: 100px;
    height: 50px;
  }

  .battery-fill span {
    font-size: 0.9rem;
  }
}

/* Animations */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.calculator-card,
.reference-card {
  animation: fadeIn 0.3s ease-out;
}

/* Status colors */
.tip-card.warning {
  border-left-color: #f56565;
  background: rgba(245, 101, 101, 0.1);
}

.tip-card.success {
  border-left-color: #48bb78;
  background: rgba(72, 187, 120, 0.1);
}

.tip-card.info {
  border-left-color: #4299e1;
  background: rgba(66, 153, 225, 0.1);
}