/* ===========================
   CSS Custom Properties
   =========================== */
:root {
  /* Colors - Dark blue/teal professional theme */
  --color-primary: #1a5276;
  --color-primary-light: #2980b9;
  --color-primary-dark: #0e2f44;
  --color-secondary: #148f77;
  --color-secondary-light: #1abc9c;
  --color-accent: #f39c12;

  /* Neutral colors */
  --color-bg: #f4f6f9;
  --color-surface: #ffffff;
  --color-border: #dce1e8;
  --color-text: #2c3e50;
  --color-text-light: #5d6d7e;
  --color-text-muted: #95a5a6;

  /* Semantic colors */
  --color-success: #27ae60;
  --color-warning: #f39c12;
  --color-error: #e74c3c;
  --color-info: #3498db;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;

  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;
  --font-size-3xl: 2.5rem;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-bold: 700;
  --line-height: 1.6;

  /* Border radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 350ms ease;

  /* Layout */
  --sidebar-width: 200px;
  --header-height: 60px;
  --max-content-width: 1200px;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: var(--line-height);
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

h1 { font-size: var(--font-size-3xl); }
h2 { font-size: var(--font-size-2xl); }
h3 { font-size: var(--font-size-xl); }
h4 { font-size: var(--font-size-lg); }

p {
  margin-bottom: var(--space-md);
  color: var(--color-text-light);
}

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

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

/* ===========================
   Layout
   =========================== */
.main-content {
  min-height: 100vh;
  padding: var(--space-xl);
  transition: margin-left var(--transition-base);
}

.main-content.with-sidebar {
  margin-left: var(--sidebar-width);
}

.container {
  max-width: var(--max-content-width);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* ===========================
   Sidebar Navigation
   =========================== */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  background-color: var(--color-primary-dark);
  color: #ffffff;
  display: flex;
  flex-direction: column;
  z-index: 1000;
  transition: transform var(--transition-base);
  overflow-y: auto;
}

.sidebar.hidden {
  display: none;
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.sidebar-title {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-bold);
  color: #ffffff;
}

.nav-list {
  list-style: none;
  padding: var(--space-md) 0;
  flex: 1;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  color: rgba(255, 255, 255, 0.8);
  transition: background-color var(--transition-fast), color var(--transition-fast);
  font-size: var(--font-size-sm);
}

.nav-link:hover,
.nav-link.active {
  background-color: rgba(255, 255, 255, 0.1);
  color: #ffffff;
}

.nav-link.active {
  border-left: 3px solid var(--color-secondary-light);
}

.nav-icon {
  font-size: var(--font-size-lg);
}

.sidebar-footer {
  padding: var(--space-md);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* ===========================
   Landing Page
   =========================== */
.landing {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  background: linear-gradient(135deg, var(--color-primary-dark) 0%, var(--color-primary) 100%);
}

.landing.hidden {
  display: none;
}

.landing-content {
  text-align: center;
  padding: var(--space-xl);
}

.logo-container {
  cursor: pointer;
  user-select: none;
  padding: var(--space-2xl);
  transition: transform var(--transition-fast);
}

.logo-container:hover {
  transform: scale(1.02);
}

.logo-container:active {
  transform: scale(0.98);
}

.logo-icon {
  font-size: 5rem;
  display: block;
  margin-bottom: var(--space-md);
}

.logo-text {
  color: #ffffff;
  font-size: var(--font-size-3xl);
  margin-bottom: var(--space-sm);
}

.logo-subtitle {
  color: rgba(255, 255, 255, 0.7);
  font-size: var(--font-size-lg);
  margin-bottom: 0;
}

/* ===========================
   Login Form
   =========================== */
.login-form-container {
  margin-top: var(--space-xl);
  animation: slideDown var(--transition-base) ease-out;
}

.login-form-container.hidden {
  display: none;
}

.login-form {
  background: var(--color-surface);
  padding: var(--space-xl);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  max-width: 380px;
  margin: 0 auto;
  text-align: left;
}

.login-title {
  text-align: center;
  margin-bottom: var(--space-lg);
  font-size: var(--font-size-xl);
  color: var(--color-primary);
}

/* ===========================
   Utility Classes
   =========================== */
.hidden {
  display: none !important;
}

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

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

.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }

/* ===========================
   Animations
   =========================== */
@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(100%);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}