/* Base styles and variables */
:root {
  /* Color palette */
  --color-primary: #0077FF;
  --color-primary-light: #4D9FFF;
  --color-primary-dark: #0055CC;
  
  --color-secondary: #00C2A8;
  --color-secondary-light: #4DD6C4;
  --color-secondary-dark: #009080;
  
  --color-accent: #FF9500;
  --color-accent-light: #FFB04D;
  --color-accent-dark: #CC7600;
  
  --color-success: #34C759;
  --color-warning: #FFCC00;
  --color-error: #FF3B30;
  
  /* Neutral colors */
  --color-white: #FFFFFF;
  --color-gray-50: #F9FAFB;
  --color-gray-100: #F3F4F6;
  --color-gray-200: #E5E7EB;
  --color-gray-300: #D1D5DB;
  --color-gray-400: #9CA3AF;
  --color-gray-500: #6B7280;
  --color-gray-600: #4B5563;
  --color-gray-700: #374151;
  --color-gray-800: #1F2937;
  --color-gray-900: #111827;
  --color-black: #000000;
  
  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen,
    Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  
  /* Spacing (8px grid) */
  --space-1: 0.5rem;  /* 8px */
  --space-2: 1rem;    /* 16px */
  --space-3: 1.5rem;  /* 24px */
  --space-4: 2rem;    /* 32px */
  --space-5: 2.5rem;  /* 40px */
  --space-6: 3rem;    /* 48px */
  
  /* Border radius */
  --radius-sm: 0.25rem;  /* 4px */
  --radius-md: 0.5rem;   /* 8px */
  --radius-lg: 0.75rem;  /* 12px */
  --radius-xl: 1rem;     /* 16px */
  
  /* Shadows */
  --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);
  
  /* Layout */
  --sidebar-width: 280px;
  --sidebar-collapsed-width: 60px;
  --header-height: 64px;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 350ms ease;
}

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

html {
  font-size: 16px;
  height: 100%;
}

body {
  font-family: var(--font-family);
  color: var(--color-gray-800);
  background-color: var(--color-gray-50);
  line-height: 1.5;
  font-weight: 400;
  height: 100%;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  line-height: 1.2;
  margin-bottom: var(--space-2);
  font-weight: 600;
  color: var(--color-gray-900);
}

h1 {
  font-size: 2rem;
}

h2 {
  font-size: 1.5rem;
}

h3 {
  font-size: 1.25rem;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-dark);
}

button {
  cursor: pointer;
  font-family: inherit;
  border: none;
  background: none;
  font-size: 1rem;
}

/* Layout */
.app-container {
  display: flex;
  height: 100%;
  position: relative;
}

.sidebar {
  width: var(--sidebar-width);
  height: 100%;
  background-color: var(--color-white);
  border-right: 1px solid var(--color-gray-200);
  position: fixed;
  left: 0;
  top: 0;
  bottom: 0;
  z-index: 100;
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-normal), width var(--transition-normal);
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-2);
  border-bottom: 1px solid var(--color-gray-200);
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-primary);
  margin: 0;
}

.logo span {
  color: var(--color-accent);
}

.sidebar-toggle {
  width: 32px;
  height: 32px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 8px 4px;
  background-color: transparent;
  border-radius: var(--radius-md);
  transition: background-color var(--transition-fast);
}

.sidebar-toggle:hover {
  background-color: var(--color-gray-100);
}

.sidebar-toggle span {
  display: block;
  height: 2px;
  width: 100%;
  background-color: var(--color-gray-600);
  transition: transform var(--transition-fast);
}

.sidebar-nav {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-2) 0;
}

.sidebar-nav ul {
  list-style: none;
}

.nav-category {
  padding: var(--space-1) var(--space-2);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-gray-500);
  margin-top: var(--space-2);
}

.sidebar-nav a {
  display: flex;
  align-items: center;
  padding: var(--space-1) var(--space-2);
  color: var(--color-gray-700);
  font-weight: 500;
  transition: background-color var(--transition-fast), color var(--transition-fast);
  border-radius: var(--radius-md);
  margin: 2px var(--space-1);
}

.sidebar-nav a:hover {
  background-color: var(--color-gray-100);
  color: var(--color-primary);
}

.sidebar-nav a.active {
  background-color: var(--color-primary-light);
  color: var(--color-white);
}

.sidebar-nav .icon {
  display: inline-block;
  width: 24px;
  margin-right: var(--space-1);
  text-align: center;
}

.sidebar-footer {
  padding: var(--space-2);
  border-top: 1px solid var(--color-gray-200);
  text-align: center;
  font-size: 0.875rem;
  color: var(--color-gray-500);
}

.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  padding: var(--space-3);
  transition: margin-left var(--transition-normal);
}

.page-header {
  margin-bottom: var(--space-3);
}

/* Standard Calculator Styles */
.calculator-container {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  margin-bottom: var(--space-4);
}

@media (min-width: 992px) {
  .calculator-container {
    flex-direction: row;
    align-items: flex-start;
  }
  
  .standard-calculator {
    flex: 1;
  }
  
  .calculator-features {
    width: 300px;
  }
}

.calculator {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
}

.calculator-display {
  background-color: var(--color-gray-800);
  color: var(--color-white);
  padding: var(--space-2);
  text-align: right;
  min-height: 100px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
}

.previous-operand {
  color: var(--color-gray-400);
  font-size: 1.25rem;
  min-height: 1.5rem;
}

.current-operand {
  font-size: 2.5rem;
  font-weight: 500;
  margin-top: var(--space-1);
  word-break: break-all;
}

.calculator-keypad {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background-color: var(--color-gray-200);
}

.key {
  padding: var(--space-2);
  font-size: 1.25rem;
  background-color: var(--color-white);
  border: none;
  transition: background-color var(--transition-fast);
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.key:active {
  transform: scale(0.98);
}

.key.number {
  background-color: var(--color-gray-50);
}

.key.number:hover {
  background-color: var(--color-gray-100);
}

.key.operator {
  background-color: var(--color-gray-100);
  font-weight: 600;
}

.key.operator:hover {
  background-color: var(--color-gray-200);
}

.key.equals {
  background-color: var(--color-primary);
  color: var(--color-white);
  grid-column: span 2;
}

.key.equals:hover {
  background-color: var(--color-primary-dark);
}

/* Calculator features */
.calculator-features {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.feature {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: var(--space-2);
  box-shadow: var(--shadow-md);
}

.calculation-history {
  max-height: 200px;
  overflow-y: auto;
  margin-bottom: var(--space-2);
  border: 1px solid var(--color-gray-200);
  border-radius: var(--radius-md);
  padding: var(--space-1);
}

.calculation-history p {
  padding: var(--space-1);
  border-bottom: 1px solid var(--color-gray-100);
}

.calculation-history p:last-child {
  border-bottom: none;
}

.empty-history {
  color: var(--color-gray-500);
  text-align: center;
  font-style: italic;
}

.clear-history-btn {
  width: 100%;
  padding: var(--space-1);
  background-color: var(--color-gray-200);
  color: var(--color-gray-700);
  border-radius: var(--radius-md);
  transition: background-color var(--transition-fast);
}

.clear-history-btn:hover {
  background-color: var(--color-gray-300);
}

.memory-buttons {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: var(--space-1);
  margin-bottom: var(--space-2);
}

.memory-btn {
  padding: var(--space-1);
  background-color: var(--color-gray-100);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 600;
  transition: background-color var(--transition-fast);
}

.memory-btn:hover {
  background-color: var(--color-gray-200);
}

.memory-display {
  padding: var(--space-1);
  background-color: var(--color-gray-100);
  border-radius: var(--radius-md);
  text-align: center;
}

/* Featured calculators */
.featured-calculators {
  margin-top: var(--space-4);
}

.calculator-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-2);
  margin-top: var(--space-2);
}

.calculator-card {
  display: block;
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: var(--space-2);
  box-shadow: var(--shadow-md);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  color: var(--color-gray-800);
}

.calculator-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  color: var(--color-gray-900);
}

.card-icon {
  font-size: 2rem;
  margin-bottom: var(--space-1);
}

.calculator-card h3 {
  margin-bottom: var(--space-1);
  color: var(--color-primary);
}

.calculator-card p {
  font-size: 0.875rem;
  color: var(--color-gray-600);
}

/* Responsive styles */
@media (max-width: 991px) {
  .sidebar {
    transform: translateX(-100%);
  }
  
  .sidebar.active {
    transform: translateX(0);
  }
  
  .main-content {
    margin-left: 0;
  }
  
  .main-content.sidebar-active {
    margin-left: var(--sidebar-width);
  }
}

@media (max-width: 576px) {
  :root {
    --sidebar-width: 100%;
  }
  
  .calculator-container {
    flex-direction: column;
  }
  
  .calculator-features {
    width: 100%;
  }
  
  .calculator-cards {
    grid-template-columns: 1fr;
  }
}

/* Print styles */
@media print {
  .sidebar {
    display: none;
  }
  
  .main-content {
    margin-left: 0;
    padding: 0;
  }
  
  .calculator-container {
    box-shadow: none;
  }
}