/* ==========================================================================
   BASE: variables, reset, animations, typography, focus ring
   ========================================================================== */

:root {
    --ios-blue: #007AFF;
    --ios-blue-hover: #006fe0;
    --link-blue: #0066cc; /* apple.com's link blue: #007AFF fails AA as text on light */
    --bg-color: #f5f5f7;
    --text-color: #5c5c5c;
    --text-heading: #1d1d1f; /* Apple near-black for crisp headlines */
    --nav-bg: rgba(255, 255, 255, 0.75);
    --card-bg: rgba(255, 255, 255, 0.7);
    --card-border: rgba(255, 255, 255, 0.6);
    --shadow-light: rgba(0, 0, 0, 0.05);
    --shadow-medium: rgba(0, 0, 0, 0.1);
    --text-muted: #6e6e73;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 90px; /* clear the sticky nav when jumping to in-page anchors */
    /* Page scrolling is vertical only; any accidentally-too-wide element
       gets clipped instead of creating sideways pan (mobile browsers grow
       the layout viewport when content overflows, which made the whole
       page wiggle left-right). `clip`, not `hidden`: hidden would turn
       this into a scroll container and break the sticky nav. */
    overflow-x: clip;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    line-height: 1.5;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Animations */
@keyframes scroll {
    /* The track holds two identical card sets; shifting by exactly half its
       width loops seamlessly, independent of card count or width. Each card
       owns its trailing gap via margin-right so -50% lands on a card boundary. */
    from { transform: translateX(0); }
    to { transform: translateX(-50%); }
}

/* Scroll reveal: elements start nudged down and transparent, then rise into
   place when they enter the viewport (an IntersectionObserver in layout.js
   adds .in-view; grid children get staggered). This selector list must stay
   in sync with REVEAL_SELECTOR / STAGGER_SELECTOR in layout.js, or an
   element would be hidden here that the observer never reveals. The state
   is triple-gated: html.js so nothing hides without JS, reduced-motion off,
   and the transition itself lives in layout.js as an inline style so card
   hover transitions come back untouched once the reveal finishes. */
@media (prefers-reduced-motion: no-preference) {
    html.js :is(.page-hero, .section-header, .hero-card, .glass-card,
        .section-cta, .cta-section, .code-cta, .carousel-container,
        .coming-soon, .article-backbar, .article-wrap,
        .featured-grid > *, .bento-grid > *):not(.in-view) {
        opacity: 0;
        transform: translateY(24px);
    }
}

/* Typography */
h1 {
    font-size: 3.5rem;
    font-weight: 700;
    letter-spacing: -0.025em;
    margin-bottom: 0.5rem;
    line-height: 1.1;
    color: var(--text-heading);
}

h2 {
    font-size: 2.2rem;
    font-weight: 600;
    letter-spacing: -0.02em;
    margin-top: 3rem;
    margin-bottom: 1.5rem;
    color: var(--text-heading);
}

h3 {
    font-size: 1.4rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    color: var(--text-heading);
}

.tagline {
    font-size: 1.35rem;
    color: var(--text-muted);
    font-weight: 400;
    margin-top: 0.5rem;
    letter-spacing: -0.01em;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.section-header {
    margin-top: 80px;
    margin-bottom: 30px;
    border-bottom: 1px solid rgba(0,0,0,0.1);
    padding-bottom: 15px;
}

/* Muted one-line subhead under a section heading */
.section-subhead { color: var(--text-muted); font-size: 0.95rem; margin-top: 5px; }

/* Keyboard focus ring: the box-shadow halo follows each element's own
   border-radius, so round buttons stay round and cards keep their corners.
   (Don't set border-radius here, or it reshapes the element on focus.) */
a:focus-visible,
button:focus-visible,
input:focus-visible,
textarea:focus-visible,
.glass-card:focus-visible,
.carousel-card:focus-visible {
    outline: none;
    box-shadow: 0 0 0 4px rgba(0, 122, 255, 0.4);
}

/* <main> receives focus when the skip link is used; don't show an outline there */
main[tabindex]:focus { outline: none; }