/* ============================================
   BASE — Reset, body, layout, header, tabs
   ============================================ */

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--nb-bg-root);
    color: var(--nb-text-primary);
    padding: var(--nb-space-md);
    min-height: 100vh;
    line-height: 1.5;
}

/* Skip link */
.skip-link {
    position: absolute;
    top: -100px;
    left: var(--nb-space-md);
    padding: var(--nb-space-sm) var(--nb-space-md);
    background: var(--nb-accent-primary);
    color: var(--nb-text-on-accent);
    font-size: 0.875rem;
    font-weight: 500;
    text-decoration: none;
    border-radius: var(--nb-radius-sm);
    z-index: 10001;
    transition: top var(--nb-transition-fast);
}
.skip-link:focus { top: var(--nb-space-md); outline: 2px solid var(--nb-text-on-accent); outline-offset: 2px; }

/* Container */
.container { width: 100%; max-width: 100%; }

/* Header */
.header {
    text-align: center;
    margin-bottom: var(--nb-space-lg);
    padding-top: var(--nb-space-sm);
}

.header h1 {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.1;
    margin-bottom: 6px;
    color: var(--nb-text-primary);
}

.header-tagline {
    font-size: 0.9375rem;
    color: var(--nb-text-muted);
    letter-spacing: 0.04em;
    margin: 0;
}

.header-tagline::after {
    content: '';
    display: block;
    width: 32px;
    height: 2px;
    background: linear-gradient(90deg, var(--nb-gradient-start), var(--nb-gradient-end));
    opacity: 0.5;
    margin: 10px auto 0;
    border-radius: 1px;
}

/* ============================================
   TOOL TABS (tab navigation)
   ============================================ */
.tool-tabs-section { margin-bottom: var(--nb-space-lg); }

.tool-tabs {
    display: flex;
    background: var(--nb-bg-layer-1);
    border: 2px solid var(--nb-bg-layer-1);
    border-radius: var(--nb-radius-md);
    overflow: hidden;
}

.tool-tab {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--nb-space-xs);
    padding: var(--nb-space-sm) var(--nb-space-xs);
    min-height: 48px;
    border: none;
    border-radius: 0;
    background: var(--nb-bg-layer-1);
    color: var(--nb-text-muted);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: background var(--nb-transition-fast), color var(--nb-transition-fast);
    position: relative;
    font-family: inherit;
}

.tool-tab svg {
    width: 18px;
    height: 18px;
    flex-shrink: 0;
}

/* Dividers between tabs */
.tool-tab:not(:last-child)::after {
    content: '';
    position: absolute;
    right: 0; top: 25%; height: 50%;
    width: 1px;
    background: var(--nb-muted-border-soft);
    transition: opacity var(--nb-transition-fast);
}
.tool-tab.active::after,
.tool-tab:has(+ .tool-tab.active)::after { opacity: 0; }

.tool-tab.active {
    background: var(--nb-bg-layer-2);
    color: var(--nb-text-primary);
    box-shadow: inset 0 0 0 2px var(--nb-accent-primary);
    border-radius: calc(var(--nb-radius-md) - 2px);
    z-index: 1;
}

.tool-tab:focus-visible {
    outline: none;
    box-shadow: inset 0 0 0 2px var(--nb-accent-primary);
    z-index: 2;
}

/* ============================================
   TOOL PANELS
   ============================================ */
.tool-panel {
    background: var(--nb-bg-layer-1);
    border-radius: var(--nb-radius-lg);
    padding: var(--nb-space-md);
    margin-bottom: var(--nb-space-md);
    display: none;
}
.tool-panel.active { display: block; }

/* Panel header row: title + fullscreen button */
.panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--nb-space-md);
    padding-bottom: var(--nb-space-md);
    border-bottom: 1px solid var(--nb-muted-border-subtle);
}

.panel-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--nb-text-primary);
}

/* Desktop: two-column layout (primary | settings) */
.tool-layout {
    display: flex;
    flex-direction: column;
    gap: var(--nb-space-md);
}

/* Primary column: display area + action row + microcopy */
.tool-primary {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--nb-space-md);
    min-width: 0;
}

/* Tool display — the outcome area */
.tool-display {
    flex: 1;
}

/* Tool settings */
.tool-settings {
    display: flex;
    flex-direction: column;
    gap: var(--nb-space-md);
}

/* Action row — sits inside .tool-primary, no extra top margin needed */
.action-row {
    display: flex;
    gap: var(--nb-space-sm);
}

/* Trust microcopy */
.trust-microcopy {
    text-align: center;
    font-size: 0.75rem;
    color: var(--nb-text-muted);
    margin-top: var(--nb-space-sm);
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
    text-align: center;
    padding: 14px var(--nb-space-lg) 20px;
    color: var(--nb-text-muted);
    font-size: 0.875rem;
}

.footer-attribution {
    color: var(--nb-text-secondary);
    font-size: 0.8125rem;
    margin-bottom: 6px;
}

.footer-link {
    color: var(--nb-text-secondary);
    text-decoration: underline;
    text-decoration-color: var(--nb-border-subtle);
    text-underline-offset: 3px;
    transition: color 0.15s ease, text-decoration-color 0.15s ease;
}

.footer-link:hover, .footer-link:focus {
    color: var(--nb-accent-primary);
    text-decoration-color: var(--nb-accent-primary);
}

.footer-nav {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 8px;
    font-size: 0.8125rem;
    flex-wrap: wrap;
    margin-top: 4px;
}

.footer-nav-divider { color: var(--nb-text-disabled); }

/* ============================================
   RESPONSIVE
   ============================================ */
@media (min-width: 768px) {
    body {
        padding: var(--nb-space-xl);
        display: flex;
        justify-content: center;
        align-items: flex-start;
    }
    .container { max-width: 720px; }
    .header h1 { font-size: 2rem; }

    .tool-layout {
        flex-direction: row;
        align-items: flex-start;
    }
    .tool-primary {
        align-self: stretch;
    }
    .tool-settings {
        width: 260px;
        flex-shrink: 0;
    }
}

@media (min-width: 1024px) {
    .container { max-width: 860px; }
}

@media (min-width: 1280px) {
    .container { max-width: 980px; }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
    :root {
        --nb-transition-fast:   0.01s linear;
        --nb-transition-normal: 0.01s linear;
    }
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}