:root {
  --bg-color: #0f172a;
  --card-bg: #1e293b;
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --accent-color: #38bdf8;
  --accent-hover: #0ea5e9;
  --success-color: #22c55e;
  --warning-color: #eab308;
  --danger-color: #ef4444;
  --border-radius: 12px;
  --font-family: 'Inter', system-ui, -apple-system, sans-serif;
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--text-primary);
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  line-height: 1.5;
}

.container {
  background-color: var(--card-bg);
  padding: 2.5rem;
  border-radius: var(--border-radius);
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.3);
  width: 100%;
  max-width: 600px;
  margin: 1rem;
}

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

h1 {
  font-size: 2rem;
  font-weight: 700;
  background: linear-gradient(to right, var(--accent-color), #818cf8);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  margin-bottom: 0.5rem;
}

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

/* Display Area */
.display-area {
  background-color: rgba(0, 0, 0, 0.2);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--border-radius);
  padding: 1.5rem;
  margin-bottom: 2rem;
  position: relative;
  transition: all 0.3s ease;
}

.display-area:focus-within {
  border-color: var(--accent-color);
  box-shadow: 0 0 0 2px rgba(56, 189, 248, 0.2);
}

.password-output {
  font-family: 'JetBrains Mono', monospace;
  font-size: 1.5rem;
  word-break: break-all;
  min-height: 2.25rem;
  display: flex;
  align-items: center;
  color: var(--text-primary);
}

.copy-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  background: transparent;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 0.5rem;
  border-radius: 6px;
  transition: all 0.2s;
}

.copy-btn:hover {
  background-color: rgba(255, 255, 255, 0.1);
  color: var(--text-primary);
}

/* Controls */
.controls {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

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

label {
  font-weight: 500;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.slider-container {
  display: flex;
  align-items: center;
  gap: 1rem;
}

input[type="range"] {
  flex: 1;
  height: 6px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 3px;
  appearance: none;
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  appearance: none;
  width: 18px;
  height: 18px;
  background: var(--accent-color);
  border-radius: 50%;
  cursor: pointer;
  transition: transform 0.1s;
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.1);
}

.length-value {
  font-family: 'JetBrains Mono', monospace;
  color: var(--accent-color);
  font-weight: 700;
  min-width: 2ch;
}

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

.checkbox-wrapper {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  cursor: pointer;
  padding: 0.75rem;
  background-color: rgba(255, 255, 255, 0.05);
  border-radius: 8px;
  transition: background-color 0.2s;
}

.checkbox-wrapper:hover {
  background-color: rgba(255, 255, 255, 0.1);
}

.checkbox-wrapper input[type="checkbox"] {
  width: 1.2rem;
  height: 1.2rem;
  accent-color: var(--accent-color);
}

.checkbox-wrapper span {
  color: var(--text-primary);
  font-size: 0.9rem;
}

/* Strength Meter */
.strength-section {
  background-color: rgba(0, 0, 0, 0.2);
  padding: 1rem;
  border-radius: 8px;
  margin-top: 1rem;
}

.strength-header {
  display: flex;
  justify-content: space-between;
  margin-bottom: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.strength-bar-bg {
  height: 6px;
  background-color: rgba(255, 255, 255, 0.1);
  border-radius: 3px;
  overflow: hidden;
}

.strength-bar-fill {
  height: 100%;
  width: 0%;
  background-color: var(--danger-color);
  transition: width 0.3s ease, background-color 0.3s ease;
}

.crack-time {
  margin-top: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.crack-time span {
  color: var(--text-primary);
  font-weight: 600;
}

/* Generate Button */
.generate-btn {
  width: 100%;
  padding: 1rem;
  background-color: var(--accent-color);
  color: white;
  border: none;
  border-radius: var(--border-radius);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 0.2s, transform 0.1s;
  margin-top: 1rem;
}

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

.generate-btn:active {
  transform: scale(0.98);
}

/* Utility classes for strength colors */
.strength-0 { background-color: var(--danger-color); }
.strength-1 { background-color: #f97316; } /* Orange */
.strength-2 { background-color: var(--warning-color); }
.strength-3 { background-color: #84cc16; } /* Lime */
.strength-4 { background-color: var(--success-color); }

@media (max-width: 480px) {
  .container {
    padding: 1.5rem;
  }
  
  h1 {
    font-size: 1.75rem;
  }
}