/* Display & Layout */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.grid { display: grid; }
.hidden { display: none !important; }
.block { display: block; }

/* Grid Columns */
.grid-cols-1 { grid-template-columns: repeat(1, minmax(0, 1fr)); }
.grid-cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

/* Spacing */
.gap-2 { gap: 0.5rem; }
.gap-4 { gap: 1rem; }
.gap-6 { gap: 1.5rem; }
.gap-8 { gap: 2rem; }

/* Margins */
.mx-auto { margin-left: auto; margin-right: auto; }
.mx-4 { margin-left: 1rem; margin-right: 1rem; }
.my-4 { margin-top: 1rem; margin-bottom: 1rem; }
.mt-4 { margin-top: 1rem; }
.mt-8 { margin-top: 2rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-4 { margin-bottom: 1rem; }
.mb-6 { margin-bottom: 1.5rem; }
.mb-8 { margin-bottom: 2rem; }
.mb-12 { margin-bottom: 3rem; }
.ml-2 { margin-left: 0.5rem; }
.m-0 { margin: 0; }

/* Paddings */
.p-2 { padding: 0.5rem; }
.p-4 { padding: 1rem; }
.p-8 { padding: 2rem; }
.pl-10 { padding-left: 2.5rem; }
.py-8 { padding-top: 2rem; padding-bottom: 2rem; }
.pt-8 { padding-top: 2rem; }

/* Sizing */
.w-full { width: 100%; }
.h-full { height: 100%; }
.max-w-md { max-width: 28rem; }
.max-w-lg { max-width: 32rem; }
.max-w-2xl { max-width: 42rem; }
.max-w-3xl { max-width: 48rem; }
.min-w-[80px] { min-width: 80px; }

/* Alignment */
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

/* Typography */
.text-xs { font-size: 0.75rem; line-height: 1rem; }
.text-sm { font-size: 0.875rem; line-height: 1.25rem; }
.text-lg { font-size: 1.125rem; line-height: 1.75rem; }
.text-xl { font-size: 1.25rem; line-height: 1.75rem; }
.text-2xl { font-size: 1.5rem; line-height: 2rem; }
.text-3xl { font-size: 1.875rem; line-height: 2.25rem; }
.text-4xl { font-size: 2.25rem; line-height: 2.5rem; }
.font-bold { font-weight: 700; }
.font-semibold { font-weight: 600; }
.uppercase { text-transform: uppercase; }
.hover\:underline:hover { text-decoration: underline; }
.hover\:text-primary:hover { color: var(--color-primary); }

/* Positioning */
.relative { position: relative; }
.absolute { position: absolute; }
.inset-0 { top: 0; right: 0; bottom: 0; left: 0; }
.top-3 { top: 0.75rem; }
.left-3 { left: 0.75rem; }
.z-10 { z-index: 10; }
.z-50 { z-index: 50; }

/* Colors */
.bg-surface { background-color: var(--color-surface); }
.bg-border { background-color: var(--color-border); }
.bg-surface\/80 { background-color: rgba(255, 255, 255, 0.8); }
html[data-theme='dark'] .bg-surface\/80 { background-color: rgba(31, 41, 55, 0.8); }

/* Borders & Shadow */
.border { border: 1px solid var(--color-border); }
.border-t { border-top: 1px solid var(--color-border); }
.border-b { border-bottom: 1px solid var(--color-border); }
.rounded { border-radius: 0.25rem; }
.rounded-lg { border-radius: 0.5rem; }
.shadow-sm { box-shadow: var(--shadow-sm); }

/* Interaction */
.pointer-events-none { pointer-events: none; }
.col-span-full { grid-column: 1 / -1; }
.col-span-3 { grid-column: span 3 / span 3; }
.overflow-hidden { overflow: hidden; }

/* Additional Sudoku Utilities */
.grid-cols-9 { grid-template-columns: repeat(9, minmax(0, 1fr)); }
.grid-rows-9 { grid-template-rows: repeat(9, minmax(0, 1fr)); }
.aspect-square { aspect-ratio: 1 / 1; }
.gap-12 { gap: 3rem; }
.pb-4 { padding-bottom: 1rem; }
.tracking-widest { letter-spacing: 0.1em; }
.tracking-wider { letter-spacing: 0.05em; }
.leading-relaxed { line-height: 1.625; }
.font-serif { font-family: var(--font-family-serif); }
.font-sans { font-family: var(--font-family-base); }
.font-mono { font-family: monospace; }

/* Additional Paddings/Margins for Sudoku UI */
.px-4 { padding-left: 1rem; padding-right: 1rem; }
.py-1 { padding-top: 0.25rem; padding-bottom: 0.25rem; }
.py-2 { padding-top: 0.5rem; padding-bottom: 0.5rem; }
.p-3 { padding: 0.75rem; }

/* Additional Positioning */
.top-1 { top: 0.25rem; }
.top-2 { top: 0.5rem; }
.right-1 { right: 0.25rem; }
.right-2 { right: 0.5rem; }
.right-3 { right: 0.75rem; }

.transition-colors { transition-property: color, background-color, border-color, text-decoration-color, fill, stroke; transition-timing-function: cubic-bezier(0.4, 0, 0.2, 1); transition-duration: 150ms; }