/* CSS Reset & Variables */
:root {
  --primary: #3498db;
  --primary-hover: #2980b9;
  --success: #27ae60;
  --danger: #e74c3c;
  --text-dark: #2c3e50;
  --text-body: #34495e;
  --text-gray: #7f8c8d;
  --text-light: #95a5a6;
  --border: #ecf0f1;
  --bg-gray: #f8f9fa;
  --white: #ffffff;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
  --shadow-md: 0 2px 8px rgba(0,0,0,0.1);
  --shadow-lg: 0 4px 12px rgba(0,0,0,0.15);
  --radius: 8px;
  --radius-lg: 12px;
  --container-width: 1200px;
  --sidebar-width: 260px;
  --transition: all 0.3s ease;
}

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

/* Base Styles */
html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  color: var(--text-body);
  line-height: 1.6;
  background: var(--bg-gray);
  min-height: 100vh;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-dark);
  line-height: 1.3;
  font-weight: 600;
}

h1 { font-size: 32px; }
h2 { font-size: 24px; }
h3 { font-size: 20px; }
h4 { font-size: 18px; }
h5 { font-size: 16px; }
h6 { font-size: 14px; }

p {
  margin-bottom: 1em;
}

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

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

/* Container */
.container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* Layout Grid */
.layout-grid {
  display: grid;
  grid-template-columns: var(--sidebar-width) 1fr;
  gap: 30px;
  padding: 30px 0;
  align-items: start;
}

.sidebar {
  position: sticky;
  top: 20px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.main-content {
  min-width: 0; /* Prevent grid blowout */
}

/* Cards */
.card {
  background: var(--white);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.card:hover {
  box-shadow: var(--shadow-md);
}

/* Buttons */
button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  border: none;
  transition: var(--transition);
}

button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

/* Forms */
input[type="text"],
input[type="search"],
input[type="email"],
textarea,
select {
  font-family: inherit;
  font-size: 14px;
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 6px;
  transition: var(--transition);
}

input:focus,
textarea:focus,
select:focus {
  outline: none;
  border-color: var(--primary);
}

/* Utility Classes */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

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

.text-right {
  text-align: right;
}

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.p-1 { padding: 0.5rem; }
.p-2 { padding: 1rem; }
.p-3 { padding: 1.5rem; }
.p-4 { padding: 2rem; }

/* Loading State */
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

.loading {
  animation: pulse 2s infinite;
}

/* Focus Styles */
:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

button:focus-visible,
a:focus-visible {
  outline-offset: 4px;
}

/* Responsive Design */
@media (max-width: 1024px) {
  :root {
    --sidebar-width: 240px;
  }
  
  .layout-grid {
    gap: 20px;
  }
}

@media (max-width: 768px) {
  .layout-grid {
    grid-template-columns: 1fr;
    gap: 20px;
  }
  
  .sidebar {
    position: static;
  }
  
  h1 { font-size: 28px; }
  h2 { font-size: 22px; }
  h3 { font-size: 18px; }
}

@media (max-width: 480px) {
  .container {
    padding: 0 15px;
  }
  
  h1 { font-size: 24px; }
  h2 { font-size: 20px; }
  h3 { font-size: 16px; }
}

/* Print Styles */
@media print {
  .sidebar,
  .header,
  .footer {
    display: none;
  }
  
  .layout-grid {
    grid-template-columns: 1fr;
  }
  
  body {
    background: white;
  }
}

/* Scrollbar Styling */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-gray);
}

::-webkit-scrollbar-thumb {
  background: var(--text-light);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-gray);
}

/* Selection */
::selection {
  background: var(--primary);
  color: white;
}

::-moz-selection {
  background: var(--primary);
  color: white;
}