/* ==========================================================================
   Focus Management System - ITCSS Layer 2 (Base)
   ========================================================================== */

/* Global focus styles for accessibility */
:focus {
    outline: none;
}

:focus-visible {
    outline: 2px solid var(--sys-color-interactive);
    outline-offset: 2px;
    border-radius: var(--border-radius-xs);
}

/* Focus styles for interactive elements */
a:focus-visible {
    outline-color: var(--sys-color-interactive);
    text-decoration: underline;
}

button:focus-visible,
input[type="submit"]:focus-visible,
.btn:focus-visible {
    outline-color: var(--sys-color-primary-default);
    outline-offset: 2px;
}

/* Form element focus styles */
input:focus-visible,
textarea:focus-visible,
select:focus-visible {
    outline-color: var(--sys-color-primary-default);
    outline-offset: 1px;
}

/* Focus within containers */
.focus-within:focus-within {
    outline: 2px solid var(--sys-color-interactive);
    outline-offset: 2px;
    border-radius: var(--border-radius-sm);
}

/* Skip links for screen readers */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--sys-color-background-inverted);
    color: var(--sys-color-text-inverted);
    padding: var(--spacing-sm) var(--spacing-md);
    text-decoration: none;
    border-radius: var(--border-radius-sm);
    z-index: var(--z-index-modal);
    font-weight: var(--font-weight-semibold);
    transition: top var(--transition-speed-fast) var(--transition-easing);
}

.skip-link:focus {
    top: 6px;
}

/* Focus trap for modals and overlays */
.focus-trap {
    position: relative;
}

.focus-trap:before,
.focus-trap:after {
    content: '';
    position: absolute;
    width: 1px;
    height: 1px;
    opacity: 0;
    pointer-events: none;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :focus-visible {
        outline-width: 3px;
        outline-style: solid;
    }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
    :focus-visible {
        transition: none;
    }
    
    .skip-link {
        transition: none;
    }
}

/* Focus indicators for different interaction modes */
.js-focus-visible :focus:not(.focus-visible) {
    outline: none;
}

/* Custom focus styles for specific components */
.card:focus-visible {
    outline-color: var(--sys-color-border-default);
    outline-width: 2px;
    outline-offset: 4px;
}

.tab:focus-visible {
    outline-color: var(--sys-color-interactive);
    outline-offset: -2px;
    border-radius: var(--border-radius-sm);
}

/* Focus management utilities */
.focus-visible-only {
    outline: none;
}

.focus-visible-only:focus-visible {
    outline: 2px solid var(--sys-color-interactive);
    outline-offset: 2px;
}

.focus-ring {
    position: relative;
}

.focus-ring:focus-visible::after {
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    right: -2px;
    bottom: -2px;
    border: 2px solid var(--sys-color-interactive);
    border-radius: inherit;
    pointer-events: none;
}