/* ===============================================
   Columns Page Styles - 컬럼
   Clean card grid layout
   =============================================== */

/* =============== HERO SECTION =============== */
.columns-hero {
    background: var(--gradient-primary);
    color: var(--white);
    padding: 120px 0 40px;
    text-align: center;
}

.columns-hero__content {
    max-width: 640px;
    margin: 0 auto;
}

.columns-hero__title {
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    font-weight: var(--font-bold);
    color: var(--white);
    line-height: 1.15;
    letter-spacing: -0.02em;
    margin-bottom: var(--spacing-sm);
}

.columns-hero__subtitle {
    font-size: clamp(1.05rem, 1.8vw, 1.25rem);
    font-weight: var(--font-light);
    color: rgba(255, 255, 255, 0.75);
    line-height: 1.6;
}

/* =============== FEATURED SECTION =============== */
.columns-featured {
    padding: 64px 0 0;
}

.columns-featured__card {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: center;
    background: var(--white);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: box-shadow var(--transition-normal), transform var(--transition-normal);
    text-decoration: none;
    color: inherit;
}

.columns-featured__card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.columns-featured__thumb {
    width: 100%;
    aspect-ratio: 16 / 10;
    object-fit: cover;
    display: block;
}

.columns-featured__thumb-placeholder {
    width: 100%;
    aspect-ratio: 16 / 10;
    background: linear-gradient(135deg, var(--secondary-light-gray) 0%, var(--secondary-medium-gray) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--secondary-dark-gray);
    font-size: 2.5rem;
    opacity: 0.4;
}

.columns-featured__body {
    padding: var(--spacing-lg) var(--spacing-xl) var(--spacing-lg) 0;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.columns-featured__meta {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--smaller-font-size);
    color: var(--neutral-blue);
}

.columns-featured__author {
    font-weight: var(--font-medium);
    color: var(--primary-deep-navy);
}

.columns-featured__date {
    color: var(--neutral-blue);
}

.columns-featured__meta-sep {
    width: 3px;
    height: 3px;
    border-radius: 50%;
    background: var(--secondary-medium-gray);
    flex-shrink: 0;
}

.columns-featured__title {
    font-size: clamp(1.375rem, 2.5vw, 1.75rem);
    font-weight: var(--font-bold);
    color: var(--primary-deep-navy);
    line-height: 1.35;
    letter-spacing: -0.01em;
    margin: 0;
}

.columns-featured__summary {
    font-size: var(--normal-font-size);
    color: var(--secondary-dark-gray);
    line-height: 1.7;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
    margin: 0;
}

.columns-featured__tags {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    margin-top: 4px;
}

.columns-featured__tag {
    display: inline-block;
    padding: 4px 12px;
    font-size: 0.8rem;
    font-weight: var(--font-medium);
    color: var(--primary-blue-accent);
    background: rgba(59, 130, 246, 0.08);
    border-radius: 100px;
    letter-spacing: 0.01em;
}

.columns-featured__action {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: var(--small-font-size);
    font-weight: var(--font-semi-bold);
    color: var(--primary-blue-accent);
    text-decoration: none;
    margin-top: 4px;
    transition: gap var(--transition-fast);
}

.columns-featured__action:hover {
    gap: 12px;
}

.columns-featured__action i {
    font-size: 0.85em;
    transition: transform var(--transition-fast);
}

.columns-featured__action:hover i {
    transform: translateX(2px);
}

/* Featured skeleton */
.columns-featured__skeleton {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    border-radius: var(--radius-lg);
    overflow: hidden;
    background: var(--white);
    box-shadow: var(--shadow-sm);
}

.columns-featured__skeleton-thumb {
    aspect-ratio: 16 / 10;
    background: linear-gradient(90deg, var(--secondary-light-gray) 25%, #eee 50%, var(--secondary-light-gray) 75%);
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
}

.columns-featured__skeleton-body {
    padding: var(--spacing-lg) var(--spacing-xl) var(--spacing-lg) 0;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.columns-featured__skeleton-line {
    height: 18px;
    border-radius: 4px;
    background: linear-gradient(90deg, var(--secondary-light-gray) 25%, #eee 50%, var(--secondary-light-gray) 75%);
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
}

.columns-featured__skeleton-line--short { width: 30%; }
.columns-featured__skeleton-line--long { width: 90%; height: 24px; }
.columns-featured__skeleton-line--medium { width: 70%; }

@keyframes shimmer {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* Featured empty state */
.columns-featured__empty {
    text-align: center;
    padding: var(--spacing-xxl) var(--spacing-lg);
    color: var(--neutral-blue);
}

.columns-featured__empty-icon {
    font-size: 3rem;
    color: var(--secondary-medium-gray);
    margin-bottom: var(--spacing-md);
}

.columns-featured__empty-text {
    font-size: var(--normal-font-size);
    color: var(--neutral-blue);
}

/* =============== CARD GRID SECTION =============== */
.columns-grid {
    padding: 48px 0 80px;
}

.columns-grid__list {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
}

/* Individual card */
.columns-card {
    display: flex;
    flex-direction: column;
    background: var(--white);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition-normal), transform var(--transition-normal);
    text-decoration: none;
    color: inherit;
}

.columns-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
}

.columns-card__thumb {
    width: 100%;
    aspect-ratio: 16 / 9;
    object-fit: cover;
    display: block;
}

.columns-card__thumb-placeholder {
    width: 100%;
    aspect-ratio: 16 / 9;
    background: linear-gradient(135deg, var(--secondary-light-gray) 0%, var(--secondary-medium-gray) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--secondary-dark-gray);
    font-size: 2rem;
    opacity: 0.35;
}

.columns-card__body {
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    gap: 10px;
    flex: 1;
}

.columns-card__meta {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: var(--smaller-font-size);
    color: var(--neutral-blue);
}

.columns-card__author {
    font-weight: var(--font-medium);
    color: var(--primary-deep-navy);
}

.columns-card__date {
    color: var(--neutral-blue);
}

.columns-card__meta-sep {
    width: 3px;
    height: 3px;
    border-radius: 50%;
    background: var(--secondary-medium-gray);
    flex-shrink: 0;
}

.columns-card__title {
    font-size: var(--h3-font-size);
    font-weight: var(--font-bold);
    color: var(--primary-deep-navy);
    line-height: 1.35;
    letter-spacing: -0.01em;
    margin: 0;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.columns-card__excerpt {
    font-size: var(--small-font-size);
    color: var(--secondary-dark-gray);
    line-height: 1.65;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
    margin: 0;
}

.columns-card__tags {
    display: flex;
    flex-wrap: wrap;
    gap: 5px;
    margin-top: auto;
    padding-top: 6px;
}

.columns-card__tag {
    display: inline-block;
    padding: 3px 10px;
    font-size: 0.75rem;
    font-weight: var(--font-medium);
    color: var(--primary-blue-accent);
    background: rgba(59, 130, 246, 0.08);
    border-radius: 100px;
}

/* Load More */
.columns-grid__more {
    text-align: center;
    margin-top: var(--spacing-xl);
}

.columns-grid__more-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 40px;
    font-size: var(--normal-font-size);
    font-weight: var(--font-semi-bold);
    color: var(--primary-blue-accent);
    background: transparent;
    border: 2px solid var(--primary-blue-accent);
    border-radius: 100px;
    cursor: pointer;
    transition: background var(--transition-fast), color var(--transition-fast);
    font-family: var(--body-font);
}

.columns-grid__more-btn:hover {
    background: var(--primary-blue-accent);
    color: var(--white);
}

.columns-grid__more-btn i {
    font-size: 0.8em;
    transition: transform var(--transition-fast);
}

.columns-grid__more-btn:hover i {
    transform: translateY(2px);
}

/* =============== RESPONSIVE =============== */

/* Tablet */
@media (max-width: 1024px) {
    .columns-grid__list {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Mobile */
@media (max-width: 768px) {
    .columns-hero {
        padding: 100px 0 48px;
    }

    .columns-featured {
        padding: 40px 0 0;
    }

    .columns-featured__card {
        grid-template-columns: 1fr;
    }

    .columns-featured__body {
        padding: var(--spacing-md);
    }

    .columns-featured__skeleton {
        grid-template-columns: 1fr;
    }

    .columns-featured__skeleton-body {
        padding: var(--spacing-md);
    }

    .columns-grid {
        padding: 32px 0 64px;
    }

    .columns-grid__list {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }

    .columns-card__title {
        font-size: 1.25rem;
    }
}