/* ============================================================
   DESIGN TOKENS
   ============================================================ */
:root {
    /* Background */
    --bg-base:       #0a0a14;
    --bg-surface:    #0f0f20;
    --bg-gradient:   linear-gradient(135deg, #0d0d1a 0%, #12082a 50%, #0a1428 100%);

    /* Glass */
    --glass-bg:      rgba(255, 255, 255, 0.06);
    --glass-bg-hover:rgba(255, 255, 255, 0.10);
    --glass-border:  rgba(255, 255, 255, 0.12);
    --glass-border-strong: rgba(255, 255, 255, 0.22);
    --glass-blur:    blur(20px);
    --glass-blur-sm: blur(10px);

    /* Accent */
    --accent-blue:   #3b82f6;
    --accent-violet: #8b5cf6;
    --accent-cyan:   #06b6d4;
    --accent-grad:   linear-gradient(135deg, #3b82f6, #8b5cf6);
    --accent-glow:   0 0 40px rgba(139, 92, 246, 0.35);

    /* Text */
    --text-primary:  #f1f5f9;
    --text-secondary:#94a3b8;
    --text-muted:    #475569;
    --text-on-dark:  #ffffff;

    /* Spacing */
    --space-xs:  0.25rem;
    --space-sm:  0.5rem;
    --space-md:  1rem;
    --space-lg:  1.5rem;
    --space-xl:  2.5rem;
    --space-2xl: 4rem;
    --space-3xl: 6rem;

    /* Typography */
    --font-sans:  'Inter', 'Noto Sans TC', system-ui, sans-serif;
    --font-size-sm:   0.875rem;
    --font-size-base: 1rem;
    --font-size-lg:   1.125rem;
    --font-size-xl:   1.25rem;
    --font-size-2xl:  1.5rem;
    --font-size-3xl:  2rem;
    --font-size-4xl:  2.75rem;
    --font-size-5xl:  3.75rem;
    --font-weight-light:  300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold:   700;
    --line-height-tight:  1.2;
    --line-height-normal: 1.6;
    --line-height-relaxed: 1.8;

    /* Border radius */
    --radius-sm:  6px;
    --radius-md:  12px;
    --radius-lg:  20px;
    --radius-xl:  28px;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm:  0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md:  0 8px 32px rgba(0, 0, 0, 0.4);
    --shadow-lg:  0 20px 60px rgba(0, 0, 0, 0.5);
    --shadow-glow-blue:   0 0 30px rgba(59, 130, 246, 0.25);
    --shadow-glow-violet: 0 0 30px rgba(139, 92, 246, 0.25);

    /* Transitions */
    --ease-out:   cubic-bezier(0.16, 1, 0.3, 1);
    --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);
    --duration-fast:   150ms;
    --duration-normal: 300ms;
    --duration-slow:   600ms;

    /* Layout */
    --container-max: 1200px;
    --container-pad: 1.5rem;
    --nav-height:    72px;
    --section-pad:   var(--space-3xl);
}

/* ============================================================
   RESET & BASE
   ============================================================ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-normal);
    line-height: var(--line-height-normal);
    color: var(--text-primary);
    background: var(--bg-base);
    background-image: var(--bg-gradient);
    background-attachment: fixed;
    min-height: 100vh;
    overflow-x: hidden;
}

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

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

ul, ol {
    list-style: none;
}

button {
    cursor: pointer;
    border: none;
    background: none;
    font: inherit;
}

/* ============================================================
   LAYOUT
   ============================================================ */
.site-wrapper {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.page-content {
    flex: 1;
    padding-top: var(--nav-height);
}

.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-pad);
}

.section {
    padding: var(--section-pad) 0;
}

/* ============================================================
   BACKGROUND ORBS (ambient glow)
   ============================================================ */
body::before,
body::after {
    content: '';
    position: fixed;
    border-radius: 50%;
    filter: blur(80px);
    pointer-events: none;
    z-index: 0;
}

body::before {
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(139, 92, 246, 0.15) 0%, transparent 70%);
    top: -100px;
    right: -100px;
}

body::after {
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(59, 130, 246, 0.12) 0%, transparent 70%);
    bottom: 10%;
    left: -100px;
}

/* ============================================================
   GLASS CARD COMPONENT
   ============================================================ */
.glass-card {
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-lg);
    transition: background var(--duration-normal) var(--ease-out),
                border-color var(--duration-normal) var(--ease-out),
                box-shadow var(--duration-normal) var(--ease-out),
                transform var(--duration-normal) var(--ease-out);
}

.glass-card:hover {
    background: var(--glass-bg-hover);
    border-color: var(--glass-border-strong);
    box-shadow: var(--shadow-md), var(--shadow-glow-violet);
    transform: translateY(-4px);
}

.glass-card--flat:hover {
    transform: none;
}

/* ============================================================
   GLASSMORPHISM NAV
   ============================================================ */
.glass-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    height: var(--nav-height);
    background: rgba(10, 10, 20, 0.7);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    border-bottom: 1px solid var(--glass-border);
    transition: background var(--duration-normal) var(--ease-out),
                border-color var(--duration-normal) var(--ease-out);
}

.glass-nav.scrolled {
    background: rgba(10, 10, 20, 0.92);
    border-bottom-color: var(--glass-border-strong);
}

.nav-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--nav-height);
    gap: var(--space-xl);
}

/* Logo */
.site-logo {
    display: flex;
    align-items: center;
    flex-shrink: 0;
    text-decoration: none;
}

.site-logo__text {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    background: var(--accent-grad);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.02em;
}

.site-logo img {
    height: 36px;
    width: auto;
}

/* Nav menu */
.site-nav {
    display: flex;
    align-items: center;
    gap: var(--space-xl);
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--space-lg);
}

.nav-menu a {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    color: var(--text-secondary);
    transition: color var(--duration-fast) var(--ease-out);
    position: relative;
    padding: var(--space-xs) 0;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 1px;
    background: var(--accent-grad);
    transition: width var(--duration-normal) var(--ease-out);
}

.nav-menu a:hover,
.nav-menu .current-menu-item > a {
    color: var(--text-primary);
}

.nav-menu a:hover::after,
.nav-menu .current-menu-item > a::after {
    width: 100%;
}

/* Nav CTA button */
.nav-cta {
    color: var(--text-on-dark) !important;
    padding: 0.5rem 1.25rem !important;
}

.nav-cta::after {
    display: none !important;
}

/* Language switcher */
.lang-switcher {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
}

.lang-switcher a {
    color: var(--text-secondary);
    transition: color var(--duration-fast);
}

.lang-switcher a:hover,
.lang-switcher .lang-item.current a {
    color: var(--accent-blue);
}

/* Mobile toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: var(--space-sm);
    z-index: 110;
}

.nav-toggle__bar {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: transform var(--duration-normal) var(--ease-out),
                opacity var(--duration-normal) var(--ease-out);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) {
    opacity: 0;
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: 0.75rem 1.75rem;
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    line-height: 1;
    cursor: pointer;
    transition: all var(--duration-normal) var(--ease-out);
    text-decoration: none;
    white-space: nowrap;
}

.btn--primary {
    background: var(--accent-grad);
    color: var(--text-on-dark);
    box-shadow: 0 4px 20px rgba(139, 92, 246, 0.35);
}

.btn--primary:hover {
    box-shadow: 0 8px 30px rgba(139, 92, 246, 0.5);
    transform: translateY(-2px);
    color: var(--text-on-dark);
}

.btn--ghost {
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur-sm);
    -webkit-backdrop-filter: var(--glass-blur-sm);
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
}

.btn--ghost:hover {
    background: var(--glass-bg-hover);
    border-color: var(--glass-border-strong);
    transform: translateY(-2px);
    color: var(--text-primary);
}

.btn--lg {
    padding: 1rem 2.5rem;
    font-size: var(--font-size-base);
}

/* ============================================================
   TYPOGRAPHY UTILITIES
   ============================================================ */
.text-gradient {
    background: var(--accent-grad);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-label {
    display: inline-block;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--accent-blue);
    margin-bottom: var(--space-md);
}

.section-title {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
    letter-spacing: -0.03em;
    color: var(--text-primary);
    margin-bottom: var(--space-lg);
}

.section-subtitle {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    line-height: var(--line-height-relaxed);
    max-width: 600px;
}

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer {
    position: relative;
    overflow: hidden;
    background: rgba(5, 5, 12, 0.8);
    border-top: 1px solid var(--glass-border);
    padding: var(--space-3xl) 0 var(--space-xl);
}

.footer-glow {
    position: absolute;
    width: 400px;
    height: 200px;
    background: radial-gradient(ellipse, rgba(139, 92, 246, 0.1), transparent 70%);
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    pointer-events: none;
}

.footer-inner {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: var(--space-2xl);
    align-items: start;
}

.footer-tagline {
    margin-top: var(--space-sm);
    font-size: var(--font-size-sm);
    color: var(--text-muted);
}

.footer-menu {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.footer-menu a {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
    transition: color var(--duration-fast);
}

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

.footer-bottom {
    grid-column: 1 / -1;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: var(--space-lg);
    border-top: 1px solid var(--glass-border);
}

.footer-copy {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
}

/* ============================================================
   BLOG POST CARDS (used in index.php & archive.php)
   ============================================================ */
.posts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: var(--space-lg);
    margin-bottom: var(--space-2xl);
}

.post-card {
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.post-card__thumb {
    display: block;
    overflow: hidden;
    border-radius: var(--radius-md) var(--radius-md) 0 0;
    aspect-ratio: 16/9;
}

.post-card__thumb img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--duration-slow) var(--ease-out);
}

.post-card:hover .post-card__thumb img {
    transform: scale(1.04);
}

.post-card__body {
    padding: var(--space-lg);
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
    flex: 1;
}

.post-card__meta {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
}

.post-card__title {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    line-height: var(--line-height-tight);
}

.post-card__title a:hover {
    color: var(--accent-blue);
}

.post-card__excerpt {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    line-height: var(--line-height-relaxed);
    flex: 1;
}

.post-card .btn {
    align-self: flex-start;
    margin-top: var(--space-sm);
}

/* Pagination */
.nav-links {
    display: flex;
    gap: var(--space-sm);
    justify-content: center;
}

.page-numbers {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    color: var(--text-secondary);
    transition: all var(--duration-fast);
}

.page-numbers.current,
.page-numbers:hover {
    background: var(--accent-grad);
    border-color: transparent;
    color: var(--text-on-dark);
}

/* Invisible reveal class (for GSAP) */
.reveal {
    opacity: 0;
    transform: translateY(30px);
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 768px) {
    :root {
        --font-size-4xl: 2rem;
        --font-size-5xl: 2.5rem;
        --section-pad: 3rem;
        --container-pad: 1rem;
    }

    .nav-toggle {
        display: flex;
    }

    .site-nav {
        position: fixed;
        top: var(--nav-height);
        left: 0;
        right: 0;
        bottom: 0;
        background: rgba(10, 10, 20, 0.97);
        backdrop-filter: var(--glass-blur);
        -webkit-backdrop-filter: var(--glass-blur);
        flex-direction: column;
        align-items: flex-start;
        gap: 0;
        padding: var(--space-xl) var(--container-pad);
        transform: translateX(100%);
        transition: transform var(--duration-normal) var(--ease-out);
        overflow-y: auto;
    }

    .site-nav.is-open {
        transform: translateX(0);
    }

    .nav-menu {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--space-md);
        width: 100%;
    }

    .nav-menu a {
        font-size: var(--font-size-lg);
        color: var(--text-primary);
    }

    .footer-inner {
        grid-template-columns: 1fr;
        gap: var(--space-xl);
    }

    .footer-bottom {
        flex-direction: column;
        gap: var(--space-md);
        text-align: center;
    }

    .posts-grid {
        grid-template-columns: 1fr;
    }
}