/* Article Filters - Advanced Filter UI */

.article-filters {
    background: var(--color-bg);
    border-radius: var(--radius-xl);
    padding: var(--spacing-6);
    margin-bottom: var(--spacing-6);
    box-shadow: var(--shadow-sm);
}

/* Quick Filter Tabs */
.article-filters__tabs {
    display: flex;
    gap: var(--spacing-2);
    margin-bottom: var(--spacing-5);
    border-bottom: 2px solid var(--color-border);
    padding-bottom: var(--spacing-2);
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.filter-tab {
    background: transparent;
    border: none;
    padding: var(--spacing-2) var(--spacing-4);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    color: var(--color-text-secondary);
    cursor: pointer;
    border-radius: var(--radius-md);
    transition: var(--transition-normal);
    white-space: nowrap;
    position: relative;
}

.filter-tab:hover {
    background: var(--color-bg-tertiary);
    color: var(--color-text);
}

.filter-tab.active {
    color: var(--color-primary);
    background: var(--color-primary-light);
}

.filter-tab.active::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--color-primary);
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        transform: scaleX(0);
    }
    to {
        transform: scaleX(1);
    }
}

/* Filter Controls */
.article-filters__controls {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-4);
}

.article-filters__form {
    width: 100%;
}

.article-filters__row {
    display: flex;
    gap: var(--spacing-3);
    align-items: center;
    flex-wrap: wrap;
}

/* Search Input */
.article-filters__search {
    position: relative;
    flex: 1;
    min-width: 250px;
}

.article-filters__search-icon {
    position: absolute;
    left: 12px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--color-text-muted);
    pointer-events: none;
}

.article-filters__input {
    width: 100%;
    padding: 10px 16px 10px 40px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    transition: var(--transition-normal);
}

.article-filters__input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px var(--color-primary-light);
}

/* Sort Dropdown */
.article-filters__sort {
    min-width: 180px;
}

.article-filters__select {
    width: 100%;
    padding: 10px 16px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    background: var(--color-bg);
    cursor: pointer;
    transition: var(--transition-normal);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='20' height='20' viewBox='0 0 24 24' fill='none' stroke='%236b7280' stroke-width='2'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 40px;
}

.article-filters__select:hover {
    border-color: var(--color-text-muted);
}

.article-filters__select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px var(--color-primary-light);
}

/* Action Buttons */
.article-filters__actions {
    display: flex;
    gap: var(--spacing-2);
}

.article-filters__button {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: 10px 20px;
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    cursor: pointer;
    transition: var(--transition-normal);
    text-decoration: none;
    border: none;
}

.article-filters__button--primary {
    background: var(--color-primary);
    color: var(--color-bg);
}

.article-filters__button--primary:hover {
    background: var(--color-primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.article-filters__button--secondary {
    background: var(--color-bg-tertiary);
    color: var(--color-text-secondary);
}

.article-filters__button--secondary:hover {
    background: var(--color-border);
    color: var(--color-text);
}

/* Filter Chips */
.article-filters__chips {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-2);
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.filter-chip {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: 6px 12px;
    background: var(--color-primary-light);
    color: var(--color-primary);
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    animation: chipSlideIn 0.3s ease;
}

@keyframes chipSlideIn {
    from {
        opacity: 0;
        transform: scale(0.8);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.filter-chip__remove {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: none;
    padding: 2px;
    cursor: pointer;
    color: var(--color-primary);
    border-radius: 50%;
    transition: var(--transition-normal);
}

.filter-chip__remove:hover {
    background: var(--color-primary-light);
    transform: rotate(90deg);
}

.filter-chip__remove svg {
    display: block;
}

/* Results Counter */
.article-filters__results {
    padding-top: var(--spacing-3);
    border-top: 1px solid var(--color-border);
}

.article-filters__count {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    font-weight: var(--font-weight-medium);
}

/* Smooth Content Transitions */
.article-filters__form,
.article-filters__chips,
.article-filters__results {
    transition: all 0.3s ease;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .article-filters {
        padding: var(--spacing-4);
    }
    
    .article-filters__tabs {
        gap: var(--spacing-1);
        padding-bottom: var(--spacing-1);
    }
    
    .filter-tab {
        padding: var(--spacing-2) var(--spacing-3);
        font-size: var(--font-size-sm);
    }
    
    .article-filters__row {
        flex-direction: column;
        align-items: stretch;
    }
    
    .article-filters__search {
        min-width: 100%;
    }
    
    .article-filters__sort {
        min-width: 100%;
    }
    
    .article-filters__actions {
        width: 100%;
    }
    
    .article-filters__button {
        flex: 1;
        justify-content: center;
    }
    
    .article-filters__chips {
        gap: var(--spacing-1);
    }
    
    .filter-chip {
        font-size: var(--font-size-xs);
        padding: 5px 10px;
    }
}

/* Loading State */
.article-filters--loading {
    opacity: 0.6;
    pointer-events: none;
}

.article-filters--loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 24px;
    height: 24px;
    border: 3px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to {
        transform: translate(-50%, -50%) rotate(360deg);
    }
}

/* Focus Visible for Accessibility */
.filter-tab:focus-visible,
.article-filters__input:focus-visible,
.article-filters__select:focus-visible,
.article-filters__button:focus-visible,
.filter-chip__remove:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* Mobile Filter Bar - Sticky with Collapse on Scroll */
.mobile-filter-bar {
    display: none;
    position: relative;
    background: var(--color-bg);
    box-shadow: var(--shadow-md);
    z-index: 40;
    margin-bottom: var(--spacing-4);
    transition: var(--transition-normal);
}

.mobile-filter-bar.hidden {
    transform: translateY(-100%);
    opacity: 0;
    display: none;
}

.mobile-filter-bar__content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-3) var(--spacing-4);
    gap: var(--spacing-3);
}

.mobile-filter-bar__info {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    flex: 1;
    min-width: 0;
}

.mobile-filter-bar__icon {
    flex-shrink: 0;
    color: var(--color-text-secondary);
}

.mobile-filter-bar__text {
    font-size: var(--font-size-sm);
    color: var(--color-text);
    font-weight: var(--font-weight-medium);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.mobile-filter-bar__actions {
    display: flex;
    gap: var(--spacing-2);
    flex-shrink: 0;
}

.mobile-filter-bar__button {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: var(--spacing-2) var(--spacing-3);
    background: var(--color-bg-tertiary);
    border: none;
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    color: var(--color-text);
    cursor: pointer;
    transition: var(--transition-normal);
}

.mobile-filter-bar__button:hover {
    background: var(--color-border);
}

.mobile-filter-bar__button--primary {
    background: var(--color-primary);
    color: var(--color-bg);
}

.mobile-filter-bar__button--primary:hover {
    background: var(--color-primary-hover);
}

.mobile-filter-bar__button svg {
    flex-shrink: 0;
}

.mobile-filter-bar__badge {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 18px;
    height: 18px;
    padding: 0 4px;
    background: var(--color-bg);
    color: var(--color-primary);
    border-radius: var(--radius-full);
    font-size: 11px;
    font-weight: var(--font-weight-semibold);
    line-height: 1;
}

@media (max-width: 768px) {
    .mobile-filter-bar {
        display: block;
    }
    
    /* Hide desktop filters on mobile */
    .article-filters {
        display: none;
    }
}


/* Reading Time Filter (Epic 14 - Requirements: 12.3) */
/* Author and Date Range Filters */
/* Advanced Filters Row - Unified Design */
.article-filters__advanced-row {
    display: flex;
    gap: var(--spacing-6);
    padding: var(--spacing-4) 0;
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
    margin-bottom: var(--spacing-4);
    align-items: start;
    flex-wrap: wrap;
}

.article-filters__filter-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-2);
}

.article-filters__filter-group--flex {
    flex: 0 1 auto;
    min-width: 0;
}

.article-filters__filter-label {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: var(--font-size-xs);
    font-weight: var(--font-weight-semibold);
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.article-filters__filter-label svg {
    width: 16px;
    height: 16px;
    color: var(--color-text-muted);
}

.article-filters__filter-buttons {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
}

.article-filters__filter-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 4px;
    padding: 10px 12px;
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    font-size: var(--font-size-xs);
    font-weight: var(--font-weight-medium);
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: var(--transition-normal);
    white-space: nowrap;
}

.article-filters__filter-btn:hover {
    background: var(--color-bg-tertiary);
    border-color: var(--color-border);
    color: var(--color-text);
}

.article-filters__filter-btn.active {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--color-bg);
    box-shadow: var(--shadow-sm);
}

.article-filters__filter-btn--clear {
    padding: 6px 8px;
    background: var(--color-error-light);
    border-color: var(--color-error-light);
    color: var(--color-error);
}

.article-filters__filter-btn--clear:hover {
    background: var(--color-error-light);
    border-color: var(--color-error);
}

.article-filters__filter-btn svg {
    width: 14px;
    height: 14px;
}

/* Mobile adjustments for advanced filters */
@media (max-width: 1024px) {
    .article-filters__advanced-row {
        flex-direction: column;
        gap: var(--spacing-5);
    }
    
    .article-filters__filter-group {
        width: 100%;
    }
    
    .article-filters__filter-group--flex {
        flex: 1 1 auto;
    }
    
    .article-filters__filter-buttons {
        width: 100%;
    }
    
    .article-filters__filter-btn {
        flex: 1;
        justify-content: center;
    }
}

@media (max-width: 768px) {
    .article-filters__advanced-row {
        padding: var(--spacing-3) 0;
        gap: var(--spacing-4);
    }
    
    .article-filters__filter-label {
        font-size: var(--font-size-xs);
    }
    
    .article-filters__filter-btn {
        font-size: var(--font-size-xs);
        padding: 5px 10px;
    }
}