/* Import Google Fonts (Roboto & Inter làm fallback chất lượng cao cho Google Sans) */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Roboto:wght@300;400;500;700&display=swap');

/* Định nghĩa hệ thống biến CSS dùng chung (Design System Variables) - LIGHT GOOGLE THEME */
:root {
  /* Google Branding Color Palette */
  --google-blue: #1a73e8;
  --google-blue-hover: #1557b0;
  --google-blue-light: #e8f0fe;
  
  --google-red: #d93025;
  --google-red-hover: #b02017;
  --google-red-light: #fce8e6;
  
  --google-yellow: #f9ab00;
  --google-yellow-hover: #d58c00;
  --google-yellow-light: #fef7e0;
  
  --google-green: #1e8e3e;
  --google-green-hover: #137333;
  --google-green-light: #e6f4ea;

  /* Neutrals & Backgrounds - Google light clean design */
  --bg-primary: #f0f4f9;       /* Google Drive Light BG */
  --bg-secondary: #ffffff;     /* Card White */
  --bg-glass: #ffffff;
  --border-glass: #dadce0;     /* Mảnh, xám sáng */
  
  --text-primary: #202124;     /* Chữ đen Google */
  --text-secondary: #5f6368;   /* Chữ phụ xám */
  --text-muted: #70757a;       /* Chữ nhạt hơn */

  /* Typography */
  --font-sans: 'Google Sans', 'Roboto', 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  
  /* Spacing System */
  --space-xs: 0.25rem;  /* 4px */
  --space-sm: 0.5rem;   /* 8px */
  --space-md: 1rem;     /* 16px */
  --space-lg: 1.5rem;   /* 24px */
  --space-xl: 2rem;     /* 32px */
  --space-xxl: 3rem;    /* 48px */

  /* Borders & Shadows */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  
  --shadow-sm: 0 1px 2px 0 rgba(60,64,67,0.3);
  --shadow-md: 0 1px 2px 0 rgba(60,64,67,0.1), 0 2px 6px 2px rgba(60,64,67,0.15);
  --shadow-lg: 0 1px 3px 0 rgba(60,64,67,0.3), 0 4px 8px 3px rgba(60,64,67,0.15);
  --shadow-glow: 0 0 8px rgba(26, 115, 232, 0.4);

  /* Transition Speed */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  overflow-x: hidden;
  background-image: none; /* Bỏ gradient tối */
}

/* Common Global Utilities */
.glass-panel {
  background: var(--bg-glass);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg); /* Mờ dịu */
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-sans);
  font-weight: 500;
  font-size: 0.95rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: var(--transition-fast);
  text-decoration: none;
  gap: var(--space-sm);
}

.btn-primary {
  background-color: var(--google-blue);
  color: white;
}

.btn-primary:hover {
  background-color: var(--google-blue-hover);
  box-shadow: var(--shadow-glow);
}

.btn-secondary {
  background-color: #ffffff;
  color: var(--google-blue);
  border: 1px solid var(--border-glass);
}

.btn-secondary:hover {
  background-color: var(--google-blue-light);
}

.btn-success {
  background-color: var(--google-green);
  color: white;
}

.btn-success:hover {
  background-color: var(--google-green-hover);
}

.btn-danger {
  background-color: var(--google-red);
  color: white;
}

.btn-danger:hover {
  background-color: var(--google-red-hover);
}

/* Form Styles */
.form-group {
  margin-bottom: var(--space-lg);
}

.form-label {
  display: block;
  font-weight: 500;
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}

.form-control {
  width: 100%;
  padding: 0.75rem 1rem;
  background-color: #f1f3f4;
  border: 1px solid transparent;
  border-bottom: 2px solid #80868b;
  border-radius: 4px 4px 0 0;
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  transition: var(--transition-fast);
}

.form-control:focus {
  outline: none;
  background-color: #e8f0fe;
  border-bottom-color: var(--google-blue);
}

.form-control::placeholder {
  color: var(--text-muted);
}