/* ==========================================================================
   FlipLock Article Pages Stylesheet
   Unified styles for story.html, learn/index.html, and article pages
   ========================================================================== */

/* --- 1. CSS Variables (Matching index.html) --- */
:root {
    --color-page: #f7f4ee;
    --color-surface: #fbf8f2;
    --color-surface-strong: #ffffff;
    --color-text: #111111;
    --color-muted: #5c5a57;
    --color-border: #d8d2c8;
    --color-dark: #111111;
    --color-dark-text: #f8f5ef;

    --shadow-soft: 0 10px 30px rgba(17, 17, 17, 0.05);
    --shadow-medium: 0 12px 30px rgba(17, 17, 17, 0.06);
    --shadow-strong: 0 20px 50px rgba(17, 17, 17, 0.08);
    --shadow-hover: 0 16px 36px rgba(17, 17, 17, 0.08);

    --radius-card: 1px;
    --radius-button: 1px;
    --radius-pill: 1px;

    --border-standard: 1px solid var(--color-border);

    --transition-fast: 160ms ease;

    --space-4: 4px;
    --space-8: 8px;
    --space-12: 12px;
    --space-16: 16px;
    --space-20: 20px;
    --space-24: 24px;
    --space-32: 32px;
    --space-40: 40px;
    --space-48: 48px;
    --space-56: 56px;
    --space-64: 64px;
    --space-72: 72px;
    --space-80: 80px;
    --space-88: 88px;
    --space-96: 96px;

    --container-max: 900px;
    --container-padding: 32px;

    --font-sans: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "SF Pro Text", sans-serif;
    --font-stack: var(--font-sans);

    --text-body-size: 17px;
    --text-body-line: 28px;
    --text-body-mobile-size: 16px;
    --text-body-mobile-line: 26px;
    --text-body-small-size: 14px;
    --text-body-small-line: 20px;
}

/* --- 2. Reset & Base --- */
*,
*::before,
*::after {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    background: var(--color-page);
    color: var(--color-text);
    font-family: var(--font-sans);
    font-size: var(--text-body-size);
    line-height: var(--text-body-line);
    text-rendering: optimizeLegibility;
    -webkit-font-smoothing: antialiased;
}

img,
video {
    display: block;
    max-width: 100%;
}

a {
    color: inherit;
    text-decoration: none;
}

button,
input,
textarea,
select {
    font: inherit;
}

button {
    cursor: pointer;
}

button:focus-visible,
a:focus-visible,
summary:focus-visible {
    outline: 2px solid var(--color-text);
    outline-offset: 3px;
}

/* --- 3. Typography --- */
h1,
h2,
h3,
p,
blockquote,
ul {
    margin: 0;
}

h1 {
    font-size: clamp(1.8rem, 3.5vw, 2.4rem);
    line-height: 1.12;
    font-weight: 800;
    letter-spacing: -0.03em;
}

h2 {
    font-size: clamp(1.5rem, 2.5vw, 1.8rem);
    line-height: 1.2;
    font-weight: 750;
    letter-spacing: -0.03em;
}

h3 {
    font-size: 1.3rem;
    line-height: 1.3;
    font-weight: 700;
    letter-spacing: -0.02em;
}

/* --- 4. Layout --- */
.container {
    width: min(100%, var(--container-max));
    margin: 0 auto;
    padding-inline: var(--container-padding);
}

.section {
    padding-block: var(--space-88);
}

/* --- 5. Buttons --- */
.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 52px;
    padding: 0 var(--space-24);
    border: 1px solid transparent;
    border-radius: var(--radius-button);
    background: var(--color-dark);
    color: var(--color-dark-text);
    font-size: 16px;
    font-weight: 700;
    line-height: 1;
    transition:
        transform var(--transition-fast),
        box-shadow var(--transition-fast),
        background-color var(--transition-fast),
        color var(--transition-fast),
        border-color var(--transition-fast);
    box-shadow: 0 8px 20px rgba(17, 17, 17, 0.08);
}

.button:hover {
    transform: translateY(-1px);
    box-shadow: 0 12px 26px rgba(17, 17, 17, 0.12);
    background: var(--color-dark);
    color: var(--color-dark-text);
}

.button--small {
    min-height: 44px;
    padding-inline: var(--space-20);
    border-color: var(--color-border);
    background: var(--color-surface);
    color: var(--color-text);
    box-shadow: none;
}

.button--light {
    background: var(--color-dark-text);
    color: var(--color-dark);
}

.button--light:hover {
    background: var(--color-dark-text);
    color: var(--color-dark);
}

/* --- 6. Cards --- */
.card-soft {
    background: var(--color-surface);
    border: var(--border-standard);
    box-shadow: var(--shadow-soft);
}

.card-elevated {
    background: var(--color-surface-strong);
    border: 1px solid rgba(17, 17, 17, 0.06);
    box-shadow: var(--shadow-medium);
}

.card-contrast {
    background: rgba(17, 17, 17, 0.035);
    border: 1px solid rgba(17, 17, 17, 0.08);
    box-shadow: none;
}

/* --- 7. Site Header (for story page) --- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    height: 72px;
    border-bottom: var(--border-standard);
    background: rgba(247, 244, 238, 0.92);
    backdrop-filter: blur(12px);
}

.site-header__inner {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-24);
}

.wordmark {
    font-size: 18px;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.back-nav {
    font-size: 18px;
    font-weight: 800;
    letter-spacing: -0.02em;
    color: var(--color-text);
    transition: color var(--transition-fast);
}

.back-nav:hover {
    color: var(--color-muted);
}

/* Download button in header */
.site-header .button--small {
    background: var(--color-dark);
    color: var(--color-dark-text);
    border-color: var(--color-dark);
    box-shadow: 0 6px 16px rgba(17, 17, 17, 0.12);
}

.site-header .button--small:hover {
    background: #000;
    color: var(--color-dark-text);
}

/* --- 8. Site Footer --- */
.site-footer {
    border-top: var(--border-standard);
    padding: var(--space-32) var(--container-padding);
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: var(--container-max);
    margin: 0 auto;
}

.site-footer__inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-24);
}

.site-footer__brand {
    font-size: var(--text-body-small-size);
    line-height: var(--text-body-small-line);
    color: var(--color-muted);
}

.site-footer__nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: flex-end;
    gap: var(--space-24);
}

.site-footer__nav a {
    font-size: var(--text-body-small-size);
    line-height: var(--text-body-small-line);
    color: var(--color-muted);
    transition: color var(--transition-fast);
}

.site-footer__nav a:hover,
.site-footer__nav a:focus-visible {
    color: var(--color-text);
}

/* Legacy footer classes */
.footer-left,
.footer-right {
    font-size: var(--text-body-small-size);
    line-height: var(--text-body-small-line);
    color: var(--color-muted);
}

.footer-right a {
    color: var(--color-muted);
    font-weight: 600;
    transition: color var(--transition-fast);
}

.footer-right a:hover {
    color: var(--color-text);
}


/* ==========================================================================
   ARTICLE PAGE STYLES
   ========================================================================== */

/* --- 9. Article Shell --- */
.article-shell {
    width: min(100%, var(--container-max));
    margin: 0 auto;
    padding: var(--space-64) var(--container-padding) var(--space-48);
}

.article-topbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-16);
    margin-bottom: var(--space-32);
    padding-bottom: var(--space-24);
    border-bottom: var(--border-standard);
}

.back-link {
    display: inline-flex;
    align-items: center;
    gap: var(--space-8);
    color: var(--color-muted);
    font-weight: 600;
    font-size: var(--text-body-small-size);
    transition: color var(--transition-fast), transform var(--transition-fast);
}

.back-link:hover {
    color: var(--color-text);
    transform: translateX(-2px);
}

.article-brand {
    display: inline-flex;
    align-items: center;
    gap: var(--space-8);
    font-weight: 800;
    font-size: 18px;
    letter-spacing: -0.02em;
}

.article-brand::before {
    content: "";
    display: inline-block;
    width: 18px;
    height: 18px;
    background-image: url("/assets/images/favicon-32x32.png");
    background-size: contain;
    background-repeat: no-repeat;
    background-position: center;
}

/* --- 10. Article Body --- */
.article-body {
    font-family: var(--font-sans);
    font-size: var(--text-body-size);
    line-height: 1.8;
    color: var(--color-text);
}

.article-body p {
    margin-bottom: 1.4em;
}

.article-body h1,
.article-body h2,
.article-body h3 {
    font-family: var(--font-sans);
    color: var(--color-text);
    font-weight: 750;
    letter-spacing: -0.03em;
    line-height: 1.2;
    margin-top: var(--space-40);
    margin-bottom: var(--space-16);
}

.article-body h1 {
    font-size: clamp(1.8rem, 3.5vw, 2.4rem);
    font-weight: 800;
}

.article-body h2 {
    font-size: clamp(1.5rem, 2.5vw, 1.8rem);
}

.article-body h3 {
    font-size: 1.3rem;
}

.article-body a {
    color: var(--color-text);
    text-decoration: underline;
    text-underline-offset: 3px;
    text-decoration-color: var(--color-border);
    transition: color var(--transition-fast);
}

.article-body a:hover {
    color: var(--color-dark);
}

.article-body ul,
.article-body ol {
    margin: var(--space-16) 0 var(--space-20) 0;
    padding-left: 1.5rem;
}

.article-body li {
    margin: var(--space-8) 0;
    color: var(--color-muted);
}

.article-body strong {
    color: var(--color-text);
    font-weight: 700;
}

.article-body em {
    font-style: italic;
}

.article-body hr {
    border: none;
    border-top: var(--border-standard);
    margin: var(--space-48) 0;
}

figure.article-figure {
    margin: var(--space-32) 0;
    border-radius: var(--radius-card);
    overflow: hidden;
    background: var(--color-surface);
    border: var(--border-standard);
    box-shadow: var(--shadow-soft);
}

figure.article-figure img {
    display: block;
    width: 100%;
    height: auto;
}

figure.article-figure figcaption {
    padding: var(--space-12) var(--space-16);
    font-size: var(--text-body-small-size);
    line-height: var(--text-body-small-line);
    color: var(--color-muted);
    background: var(--color-surface);
    border-top: var(--border-standard);
}


/* ==========================================================================
   STORY PAGE STYLES
   ========================================================================== */

/* --- 11. Story Layout --- */
.story-container {
    width: min(100%, 800px);
    margin: 0 auto;
    padding: var(--space-64) var(--container-padding);
}

.noise-curtain {
    display: none;
}

/* --- 12. Floating Toolbar (Story) --- */
.floating-toolbar {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(247, 244, 238, 0.92);
    backdrop-filter: blur(12px);
    border-bottom: var(--border-standard);
    padding: 15px var(--container-padding);
}

.toolbar-inner {
    max-width: var(--container-max);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.back-btn {
    color: var(--color-text);
    font-weight: 700;
    font-size: var(--text-body-small-size);
    transition: color var(--transition-fast);
}

.back-btn:hover {
    color: var(--color-muted);
}

.brutalist-btn {
    display: inline-flex;
    align-items: center;
    padding: var(--space-12) var(--space-24);
    background: var(--color-dark);
    color: var(--color-dark-text);
    border: 1px solid transparent;
    border-radius: var(--radius-button);
    font-weight: 700;
    font-size: var(--text-body-small-size);
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.brutalist-btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 8px 20px rgba(17, 17, 17, 0.08);
    background: var(--color-dark);
    color: var(--color-dark-text);
}

.btn-sm {
    padding: var(--space-8) var(--space-16);
    font-size: 13px;
}

/* --- 13. Story Header --- */
.story-header {
    margin-bottom: var(--space-48);
}

.header-image {
    width: 100%;
    height: auto;
    border-radius: var(--radius-card);
    margin-bottom: var(--space-32);
    box-shadow: var(--shadow-medium);
}

.story-header h1 {
    font-size: clamp(2rem, 4vw, 2.8rem);
    font-weight: 800;
    letter-spacing: -0.03em;
    text-align: center;
}

.amber-text {
    color: var(--color-text);
}

/* Story Footer Amber Text - White on dark background */
.story-footer .amber-text {
    color: var(--color-dark-text);
}

/* --- 14. Story Content --- */
.story-content {
    font-size: var(--text-body-size);
    line-height: 1.8;
}

.story-block {
    margin-bottom: var(--space-40);
}

.story-content h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin: var(--space-32) 0 var(--space-16) 0;
    letter-spacing: -0.02em;
}

.story-content p {
    margin-bottom: var(--space-20);
    color: var(--color-muted);
    line-height: 1.8;
}

.story-content strong {
    color: var(--color-text);
}

.story-content em {
    font-style: italic;
}

/* --- 15. Story Footer --- */
.story-footer {
    margin-top: var(--space-64);
    padding: var(--space-48) var(--space-32);
    background: var(--color-dark);
    color: var(--color-dark-text);
    border-radius: var(--radius-card);
    text-align: center;
}

.story-footer h2 {
    font-size: 1.6rem;
    font-weight: 800;
    margin-bottom: var(--space-20);
}

.story-footer p {
    color: rgba(248, 245, 239, 0.8);
    margin-bottom: var(--space-24);
    line-height: 1.7;
}

.story-footer strong {
    color: var(--color-dark-text);
    font-weight: 700;
}

.card-divider {
    display: none;
}

/* Story Footer Button - White background on dark background */
.story-footer .brutalist-btn {
    background: var(--color-dark-text);
    color: var(--color-dark);
    border: 1px solid var(--color-dark-text);
}

.story-footer .brutalist-btn:hover {
    background: transparent;
    color: var(--color-dark-text);
    border: 1px solid var(--color-dark-text);
}


/* ==========================================================================
   LEARN LIST PAGE STYLES
   ========================================================================== */

/* --- 16. Learn Hero --- */
.learn-hero {
    min-height: 50vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-96) var(--container-padding) var(--space-64);
    text-align: center;
}

.learn-hero-inner {
    max-width: 700px;
}

.learn-hero-tag {
    font-size: var(--text-body-small-size);
    font-weight: 700;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    color: var(--color-muted);
    margin-bottom: var(--space-24);
}

.learn-hero-title {
    font-size: clamp(2rem, 5vw, 3.2rem);
    font-weight: 800;
    line-height: 1.05;
    letter-spacing: -0.04em;
    margin-bottom: var(--space-24);
}

.learn-hero-sub {
    font-size: var(--text-body-size);
    line-height: 1.7;
    color: var(--color-muted);
    max-width: 550px;
    margin: 0 auto;
}

.learn-separator {
    text-align: center;
    color: var(--color-border);
    font-size: 12px;
    letter-spacing: 6px;
    user-select: none;
    padding: 0 var(--container-padding);
    margin-bottom: var(--space-80);
    overflow: hidden;
    white-space: nowrap;
}

/* --- 17. Learn Articles --- */
.learn-articles {
    padding: 0 var(--container-padding) var(--space-80);
    display: flex;
    flex-direction: column;
    align-items: center;
}

.learn-list {
    width: 100%;
    max-width: var(--container-max);
    display: flex;
    flex-direction: column;
}

/* --- 18. Article Card --- */
.article-card {
    border-top: var(--border-standard);
    padding: var(--space-40) 0;
    display: grid;
    grid-template-columns: 60px 1fr;
    gap: var(--space-32);
    align-items: start;
    text-decoration: none;
    color: inherit;
    transition: opacity var(--transition-fast);
}

.article-card:hover {
    opacity: 0.8;
}

.article-card:last-of-type {
    border-bottom: var(--border-standard);
}

.article-card-num {
    font-size: 1.4rem;
    font-weight: 700;
    line-height: 1;
    padding-top: var(--space-4);
}

.article-card-body {
    display: flex;
    flex-direction: column;
    gap: var(--space-12);
}

.article-card-title {
    font-size: clamp(1.1rem, 2vw, 1.4rem);
    font-weight: 700;
    line-height: 1.25;
    letter-spacing: -0.02em;
}

.article-card-excerpt {
    font-size: 15px;
    line-height: 1.7;
    color: var(--color-muted);
}

.article-card-cta {
    display: inline-flex;
    align-items: center;
    gap: var(--space-8);
    font-size: 13px;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    transition: gap var(--transition-fast);
}

.article-card:hover .article-card-cta {
    gap: var(--space-16);
}

/* --- 19. Learn CTA --- */
.learn-cta {
    padding: var(--space-80) var(--container-padding) var(--space-96);
    display: flex;
    align-items: center;
    justify-content: center;
}


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

/* --- 20. Tablet (max-width: 1023px) --- */
@media (max-width: 1023px) {
    .site-footer__inner {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--space-16);
    }

    .site-footer__nav {
        justify-content: flex-start;
    }
}

/* --- 21. Mobile (max-width: 767px) --- */
@media (max-width: 767px) {
    :root {
        --container-padding: 16px;
    }

    body {
        font-size: var(--text-body-mobile-size);
        line-height: var(--text-body-mobile-line);
    }

    /* Article */
    .article-shell {
        padding: var(--space-40) var(--container-padding) var(--space-32);
    }

    .article-topbar {
        margin-bottom: var(--space-24);
        padding-bottom: var(--space-20);
    }

    .article-body {
        font-size: var(--text-body-mobile-size);
        line-height: var(--text-body-mobile-line);
    }

    .article-body h1 {
        font-size: clamp(1.6rem, 6vw, 2rem);
    }

    .article-body h2 {
        font-size: clamp(1.3rem, 4vw, 1.5rem);
    }

    /* Story */
    .story-container {
        padding: var(--space-40) var(--container-padding);
    }

    .story-header h1 {
        font-size: clamp(1.8rem, 8vw, 2.4rem);
    }

    .story-footer {
        padding: var(--space-32) var(--space-20);
    }

    /* Learn */
    .learn-hero {
        min-height: 40vh;
        padding: var(--space-80) var(--container-padding) var(--space-40);
    }

    .article-card {
        grid-template-columns: 1fr;
        gap: var(--space-12);
        padding: var(--space-32) 0;
    }

    .article-card-num {
        font-size: 1.1rem;
    }

    .article-card-title {
        font-size: 1.1rem;
    }

    /* Buttons */
    .button,
    .brutalist-btn {
        width: 100%;
        min-height: 52px;
    }

    .button--small,
    .btn-sm {
        width: auto;
    }

    /* Footer */
    .site-footer__inner {
        flex-direction: column;
        align-items: flex-start;
    }

    .site-footer__nav {
        justify-content: flex-start;
        gap: var(--space-16);
    }
}


/* ==========================================================================
   ACCESSIBILITY
   ========================================================================== */

/* --- 22. Reduced Motion --- */
@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* --- 23. Skip Link --- */
.skip-link {
    position: absolute;
    left: var(--space-16);
    top: -48px;
    z-index: 1000;
    padding: var(--space-12) var(--space-16);
    border-radius: var(--radius-button);
    background: var(--color-dark);
    color: var(--color-dark-text);
    transition: top var(--transition-fast);
}

.skip-link:focus {
    top: var(--space-16);
}


/* ==========================================================================
   ANIMATIONS
   ========================================================================== */

/* --- 24. Scroll Reveal --- */
.reveal-up {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease, transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

.reveal-stagger {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

.is-visible {
    opacity: 1;
    transform: translateY(0);
}


/* ==========================================================================
   HOVER EFFECTS
   ========================================================================== */

/* --- 25. Card Hover --- */
.card-soft:hover,
.card-elevated:hover,
.card-contrast:hover {
    box-shadow: var(--shadow-hover);
    transform: translateY(-1px);
}