/* Design System Tokens (8px / 4px Spacing Scale) */
:root {
    --space-1: 0.25rem;  /* 4px */
    --space-2: 0.5rem;   /* 8px */
    --space-3: 0.75rem;  /* 12px */
    --space-4: 1rem;     /* 16px */
    --space-5: 1.25rem;  /* 20px */
    --space-6: 1.5rem;   /* 24px */
    --space-8: 2rem;     /* 32px */
    --space-10: 2.5rem;  /* 40px */
    --space-12: 3rem;    /* 48px */

    --container-max-width: 1440px;
}

/* Page Container - Global Enveloping Layout Component */
.page-container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: var(--space-6);
    padding: var(--space-4);
}

@media (min-width: 640px) {
    .page-container {
        padding: var(--space-6);
    }
}

@media (min-width: 1024px) {
    .page-container {
        padding: var(--space-6) var(--space-8);
    }
}

/* Page Header Component */
.page-header {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

@media (min-width: 640px) {
    .page-header {
        flex-direction: row;
        align-items: center;
        justify-content: space-between;
        gap: var(--space-4);
    }
}

.page-header-info {
    display: flex;
    flex-direction: column;
    gap: var(--space-1);
}

.page-header-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.03em;
    line-height: 1.25;
}

.page-header-subtitle {
    font-size: 0.825rem;
    color: var(--text-secondary);
    line-height: 1.4;
}

.page-header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    flex-wrap: wrap;
}

/* Section Stack (Vertical Rhythm) */
.section-stack {
    display: flex;
    flex-direction: column;
    gap: var(--space-6);
}

/* Metrics Grid Component */
.metrics-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-3);
}

@media (min-width: 640px) {
    .metrics-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-4);
    }
}

@media (min-width: 1024px) {
    .metrics-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: var(--space-6);
    }
}

.metrics-grid-4 {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-3);
}

@media (min-width: 640px) {
    .metrics-grid-4 {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-4);
    }
}

@media (min-width: 1024px) {
    .metrics-grid-4 {
        grid-template-columns: repeat(4, 1fr);
        gap: var(--space-6);
    }
}

/* Content Grid Components */
.content-grid-2 {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-4);
}

@media (min-width: 768px) {
    .content-grid-2 {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-6);
    }
}

.content-grid-3 {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-4);
}

@media (min-width: 768px) {
    .content-grid-3 {
        grid-template-columns: repeat(3, 1fr);
        gap: var(--space-6);
    }
}

.content-grid-sidebar {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-4);
}

@media (min-width: 1024px) {
    .content-grid-sidebar {
        grid-template-columns: 1fr 340px;
        gap: var(--space-6);
    }
}

/* Card Surface Component */
.card-surface {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: var(--space-4);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

@media (min-width: 640px) {
    .card-surface {
        padding: var(--space-5);
    }
}

@media (min-width: 1024px) {
    .card-surface {
        padding: var(--space-6);
    }
}

.card-surface-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-2);
    flex-wrap: wrap;
}

.card-surface-title {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.card-surface-subtitle {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Toolbar & Filters Container Component */
.toolbar-container {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: var(--space-3) var(--space-4);
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
    box-shadow: var(--shadow-sm);
}

@media (min-width: 640px) {
    .toolbar-container {
        padding: var(--space-4);
    }
}

.filter-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-3);
    align-items: center;
    width: 100%;
}

@media (min-width: 640px) {
    .filter-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-3);
    }
}

@media (min-width: 1024px) {
    .filter-grid {
        grid-template-columns: 2fr 1fr 1fr 1fr auto;
        gap: var(--space-3);
    }
}