/**
 * Kids Learners — platform design tokens (v1)
 *
 * Source of truth for spacing, type, color, layout, motion, and z-index.
 * Component CSS in kl-platform.css and kl-single.css MUST consume these tokens.
 *
 * @package Kids_Learners_Classic
 */

:root {
	/* —— Typography —— */
	--kl-font: "Plus Jakarta Sans", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
	--kl-font-display: "DM Serif Display", Georgia, "Times New Roman", serif;

	--kl-text-xs: 0.75rem;
	--kl-text-sm: 0.875rem;
	--kl-text-base: 1rem;
	--kl-text-md: 0.9375rem;
	--kl-text-lg: 1.125rem;
	--kl-text-xl: 1.25rem;
	--kl-text-2xl: 1.5rem;
	--kl-text-3xl: clamp(2rem, 4.5vw, 2.75rem);
	--kl-text-4xl: clamp(2.25rem, 5vw, 3.25rem);
	--kl-text-display: clamp(2.25rem, 5.5vw, 3.5rem);
	--kl-text-hero-lead: clamp(1.0625rem, 1.6vw, 1.1875rem);

	--kl-leading-tight: 1.15;
	--kl-leading-snug: 1.35;
	--kl-leading-normal: 1.5;
	--kl-leading-relaxed: 1.7;
	--kl-leading-editorial: 1.45;

	--kl-weight-regular: 400;
	--kl-weight-medium: 500;
	--kl-weight-semibold: 600;
	--kl-weight-bold: 700;
	--kl-weight-extrabold: 800;

	--kl-tracking-tight: -0.01em;
	--kl-tracking-normal: 0;
	--kl-tracking-wide: 0.04em;
	--kl-tracking-wider: 0.06em;

	/* —— Color: ink & surfaces —— */
	--kl-ink: #1a1f2e;
	--kl-ink-muted: #5c6370;
	--kl-body-muted: #4a5568;
	--kl-ink-subtle: #8b929e;
	--kl-surface: #ffffff;
	--kl-surface-soft: #faf9f6;
	--kl-surface-muted: #f3f1ec;
	--kl-surface-warm: #f7f4ef;
	--kl-surface-elevated: #ffffff;
	--kl-surface-inverse: #111827;

	/* —— Color: brand & accents —— */
	--kl-primary: #4f8cff;
	--kl-primary-dark: #3b7dd8;
	--kl-primary-soft: #eef4fc;
	--kl-accent: #e8913a;
	--kl-accent-soft: #fef6ee;
	--kl-mint: #3d9a7a;
	--kl-mint-soft: #ecf7f2;
	--kl-violet: #6b5fc7;
	--kl-violet-soft: #f2f0fb;

	/* —— Color: semantic —— */
	--kl-success: #059669;
	--kl-warning: #d97706;
	--kl-error: #dc2626;
	--kl-info: #0284c7;
	--kl-border: #e8e4de;
	--kl-border-strong: #d6d0c8;
	--kl-focus-ring: rgba(79, 140, 255, 0.45);

	/* —— Color: content-type accents —— */
	--kl-type-worksheet: #4f8cff;
	--kl-type-story: #a78bfa;
	--kl-type-guide: #06b6d4;
	--kl-type-clipart: #22c55e;
	--kl-type-collection: #f59e0b;

	/* —— Color: difficulty —— */
	--kl-difficulty-easy: #22c55e;
	--kl-difficulty-medium: #f59e0b;
	--kl-difficulty-hard: #ef4444;

	/* —— Spacing scale (4px base) —— */
	--kl-space-0: 0;
	--kl-space-1: 0.25rem;
	--kl-space-2: 0.5rem;
	--kl-space-3: 0.75rem;
	--kl-space-4: 1rem;
	--kl-space-5: 1.25rem;
	--kl-space-6: 1.5rem;
	--kl-space-8: 2rem;
	--kl-space-10: 2.5rem;
	--kl-space-12: 3rem;
	--kl-space-16: 4rem;
	--kl-space-20: 5rem;

	--kl-section-gap: var(--kl-space-12);
	--kl-section-gap-sm: var(--kl-space-8);
	--kl-section-gap-lg: var(--kl-space-16);
	--kl-section-gap-breathe: var(--kl-space-20);
	--kl-stack-gap: var(--kl-space-4);
	--kl-stack-gap-lg: var(--kl-space-6);
	--kl-card-gap: var(--kl-space-4);
	--kl-grid-gap: var(--kl-space-4);
	--kl-grid-gap-lg: var(--kl-space-6);
	--kl-sidebar-gap: var(--kl-space-6);

	/* —— Locked grid systems (§49 — no template drift) —— */
	--kl-grid-card-min: 11.5rem;
	--kl-grid-card-min-compact: 8.75rem;
	--kl-hub-grid-min: 15rem;
	--kl-letter-grid-min: 3.5rem;

	/* —— Editorial measure —— */
	--kl-measure-narrow: 36rem;
	--kl-measure-comfort: 42rem;
	--kl-measure-wide: 48rem;

	/* —— Layout —— */
	--kl-container: min(1100px, calc(100% - 2rem));
	--kl-container-wide: min(1280px, calc(100% - 2rem));
	--kl-container-narrow: min(42rem, calc(100% - 2rem));
	--kl-container-reading: min(48rem, calc(100% - 2rem));
	--kl-sidebar-width: 320px;
	--kl-sidebar-width-lg: 360px;
	--kl-header-h: 4rem;
	--kl-header-max: 90rem;

	/* —— Radius —— */
	--kl-radius-xs: 6px;
	--kl-radius-sm: 10px;
	--kl-radius: 14px;
	--kl-radius-lg: 18px;
	--kl-radius-xl: 24px;
	--kl-radius-pill: 999px;

	/* —— Shadow —— */
	--kl-shadow-none: none;
	--kl-shadow-xs: 0 1px 2px rgba(26, 31, 46, 0.04);
	--kl-shadow: var(--kl-shadow-xs);
	--kl-shadow-md: 0 4px 14px rgba(26, 31, 46, 0.06);
	--kl-shadow-hover: 0 8px 28px rgba(26, 31, 46, 0.08);
	--kl-shadow-lg: 0 16px 40px rgba(26, 31, 46, 0.1);
	--kl-shadow-sticky: 0 -4px 20px rgba(26, 31, 46, 0.05);

	/* —— Border —— */
	--kl-border-width: 1px;
	--kl-border-width-strong: 2px;

	/* —— Z-index —— */
	--kl-z-base: 1;
	--kl-z-dropdown: 20;
	--kl-z-sticky: 30;
	--kl-z-header: 40;
	--kl-z-overlay: 50;
	--kl-z-modal: 60;
	--kl-z-toast: 70;

	/* —— Motion —— */
	--kl-duration-fast: 120ms;
	--kl-duration: 180ms;
	--kl-duration-slow: 280ms;
	--kl-ease: cubic-bezier(0.4, 0, 0.2, 1);
	--kl-ease-out: cubic-bezier(0, 0, 0.2, 1);

	/* —— Cards & media —— */
	--kl-card-radius: var(--kl-radius);
	--kl-card-padding: var(--kl-space-4);
	--kl-card-padding-sm: var(--kl-space-3);
	--kl-card-media-radius: var(--kl-radius-sm);

	/* —— Hero atmosphere —— */
	--kl-hero-glow-primary: radial-gradient(ellipse 75% 55% at 8% 0%, color-mix(in srgb, var(--kl-primary) 14%, transparent) 0%, transparent 62%);
	--kl-hero-glow-warm: radial-gradient(ellipse 55% 45% at 92% 8%, color-mix(in srgb, var(--kl-accent) 10%, transparent) 0%, transparent 58%);
	--kl-hero-bg: var(--kl-hero-glow-primary), var(--kl-hero-glow-warm), var(--kl-surface-soft);
	--kl-thumb-ratio-worksheet: 4 / 5;
	--kl-thumb-ratio-clipart: 1 / 1;
	--kl-thumb-ratio-story: 16 / 10;
	--kl-thumb-ratio-guide: 16 / 10;
	--kl-preview-max-h: 420px;

	/* —— Touch & a11y —— */
	--kl-touch-min: 44px;
	--kl-focus-outline: 2px solid var(--kl-primary);
	--kl-focus-offset: 2px;
}

@media (min-width: 768px) {
	:root {
		--kl-header-h: 5rem;
		--kl-grid-gap: var(--kl-space-5);
		--kl-section-gap: var(--kl-space-16);
	}
}

@media (min-width: 1024px) {
	:root {
		--kl-container: min(1100px, calc(100% - 3rem));
		--kl-grid-gap-lg: var(--kl-space-8);
	}
}

.kl-type-display {
	font-family: var(--kl-font-display);
	font-weight: var(--kl-weight-regular);
	letter-spacing: var(--kl-tracking-tight);
	line-height: var(--kl-leading-tight);
	color: var(--kl-ink);
}

.kl-type-h1 {
	font-family: var(--kl-font-display);
	font-size: var(--kl-text-display);
	line-height: var(--kl-leading-tight);
	font-weight: var(--kl-weight-regular);
	letter-spacing: var(--kl-tracking-tight);
	color: var(--kl-ink);
}

.kl-type-h2 {
	font-family: var(--kl-font-display);
	font-size: var(--kl-text-2xl);
	line-height: var(--kl-leading-snug);
	font-weight: var(--kl-weight-regular);
	letter-spacing: var(--kl-tracking-tight);
	color: var(--kl-ink);
}

.kl-type-h3 {
	font-family: var(--kl-font);
	font-size: var(--kl-text-xl);
	line-height: var(--kl-leading-snug);
	font-weight: var(--kl-weight-bold);
	color: var(--kl-ink);
}

.kl-type-h4 {
	font-family: var(--kl-font);
	font-size: var(--kl-text-lg);
	line-height: var(--kl-leading-snug);
	font-weight: var(--kl-weight-semibold);
	color: var(--kl-ink);
}

.kl-type-section-label {
	font-family: var(--kl-font);
	font-size: var(--kl-text-xs);
	font-weight: var(--kl-weight-semibold);
	text-transform: uppercase;
	letter-spacing: var(--kl-tracking-wider);
	color: var(--kl-ink-subtle);
}

.kl-type-meta {
	font-size: var(--kl-text-sm);
	line-height: var(--kl-leading-normal);
	color: var(--kl-ink-muted);
}

.kl-type-body {
	font-size: var(--kl-text-base);
	line-height: var(--kl-leading-relaxed);
	color: var(--kl-body-muted);
}

.kl-type-caption {
	font-size: var(--kl-text-xs);
	line-height: var(--kl-leading-normal);
	color: var(--kl-ink-subtle);
}

.kl-type-edu-note {
	font-size: var(--kl-text-sm);
	line-height: var(--kl-leading-relaxed);
	color: var(--kl-body-muted);
}

.kl-skeleton {
	background: linear-gradient(
		90deg,
		var(--kl-surface-muted) 0%,
		var(--kl-surface-soft) 50%,
		var(--kl-surface-muted) 100%
	);
	background-size: 200% 100%;
	animation: kl-skeleton-pulse 1.2s ease-in-out infinite;
	border-radius: var(--kl-radius-sm);
}

@keyframes kl-skeleton-pulse {
	0% {
		background-position: 100% 0;
	}
	100% {
		background-position: -100% 0;
	}
}