/* ============================================================
   cosmos.css — shared visual language for the observation deck
   used by:  cosmos.html  and  blogs/<slug>/index.html
   ============================================================ */

:root {
    --bg: #06081a;
    --bg-2: #0a0e2e;
    --cyan: #7ee7ff;
    --lavender: #b08cff;
    --warm: #ffd56b;
    --text: #d8def0;
    --text-dim: #7d8aa3;
    --text-faint: #4a546b;
    --grid: rgba(126, 231, 255, 0.04);
}

* { box-sizing: border-box; }

html, body {
    margin: 0;
    padding: 0;
    min-height: 100vh;
    background: var(--bg);
    color: var(--text);
    font-family: 'Inter', -apple-system, sans-serif;
    font-weight: 300;
    overflow-x: hidden;
}

/* --- background layers --- */
.cosmos-bg {
    position: fixed;
    inset: 0;
    z-index: 0;
    pointer-events: none;
    overflow: hidden;
}
.nebula {
    position: absolute; inset: 0;
    background:
        radial-gradient(ellipse 60% 45% at 18% 28%, rgba(176, 140, 255, 0.16) 0%, transparent 65%),
        radial-gradient(ellipse 55% 40% at 82% 72%, rgba(126, 231, 255, 0.12) 0%, transparent 65%),
        radial-gradient(circle at 50% 100%, rgba(255, 213, 107, 0.05) 0%, transparent 50%),
        linear-gradient(180deg, var(--bg) 0%, var(--bg-2) 70%, var(--bg) 100%);
}
.grid {
    position: absolute; inset: 0;
    background-image:
        linear-gradient(var(--grid) 1px, transparent 1px),
        linear-gradient(90deg, var(--grid) 1px, transparent 1px);
    background-size: 48px 48px;
    -webkit-mask-image: radial-gradient(ellipse 80% 80% at center, black 30%, transparent 85%);
            mask-image: radial-gradient(ellipse 80% 80% at center, black 30%, transparent 85%);
}
.starfield { position: absolute; inset: 0; }
.star {
    position: absolute;
    background: #fff;
    border-radius: 50%;
    animation: twinkle ease-in-out infinite alternate;
}
.star.s { width: 1px; height: 1px; opacity: 0.45; }
.star.m { width: 2px; height: 2px; opacity: 0.75; }
.star.l { width: 2.5px; height: 2.5px; opacity: 1; box-shadow: 0 0 5px rgba(255,255,255,0.7); }
@keyframes twinkle {
    from { opacity: 0.25; }
    to   { opacity: 1; }
}

/* --- layout --- */
.deck {
    position: relative;
    z-index: 1;
    max-width: 760px;
    margin: 0 auto;
    padding: 32px 32px 140px;
}

/* --- status bar --- */
.status-bar {
    position: fixed;
    top: 0; left: 0; right: 0;
    z-index: 2;
    background: rgba(6, 8, 26, 0.7);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border-bottom: 1px solid rgba(126, 231, 255, 0.12);
    padding: 8px 24px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7em;
    color: var(--text-dim);
    letter-spacing: 0.08em;
    text-transform: uppercase;
    display: flex;
    gap: 24px;
    flex-wrap: wrap;
}
.status-bar .live::before {
    content: '●';
    color: #5be58a;
    margin-right: 6px;
    animation: pulse-dot 2s ease-in-out infinite;
    display: inline-block;
}
@keyframes pulse-dot {
    0%, 100% { opacity: 0.6; }
    50%      { opacity: 1; text-shadow: 0 0 6px #5be58a; }
}
.status-bar .sep { color: var(--text-faint); }

/* --- deck header --- */
.deck-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 56px;
    margin-bottom: 64px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
}
.back-link {
    color: var(--cyan);
    text-decoration: none;
    letter-spacing: 0.04em;
    transition: text-shadow 0.3s ease, transform 0.3s ease;
}
.back-link:hover {
    text-decoration: none;
    color: var(--cyan);
    text-shadow: 0 0 10px rgba(126, 231, 255, 0.7);
    transform: translateX(-3px);
}
.deck-tag { color: var(--text-faint); }

/* --- hero --- */
h1.hero {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 400;
    font-size: 2.4em;
    margin: 0 0 16px;
    color: var(--text);
    letter-spacing: -0.01em;
    min-height: 1.2em;
}
h1.hero.typing::after {
    content: '▮';
    color: var(--cyan);
    margin-left: 4px;
    animation: blink 0.8s steps(2) infinite;
}
@keyframes blink {
    0%, 50%   { opacity: 1; }
    51%, 100% { opacity: 0; }
}
.lede {
    font-family: 'JetBrains Mono', monospace;
    color: var(--text-dim);
    font-size: 0.95em;
    line-height: 1.8;
    margin: 0 0 72px;
}
.lede .hl { color: var(--lavender); }

/* --- deck blocks --- */
section.block {
    margin-bottom: 56px;
}
.block-header {
    display: flex;
    align-items: baseline;
    gap: 10px;
    margin-bottom: 24px;
    padding-bottom: 12px;
    border-bottom: 1px solid rgba(126, 231, 255, 0.1);
    font-family: 'JetBrains Mono', monospace;
}
.block-header h2 {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 500;
    font-size: 1.0em;
    color: var(--cyan);
    letter-spacing: 0.06em;
    margin: 0;
    text-transform: uppercase;
}
.block-header .bracket {
    color: var(--text-faint);
    font-size: 1.0em;
}
.block-header .meta {
    margin-left: auto;
    color: var(--text-faint);
    font-size: 0.78em;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.packet {
    padding: 18px 22px;
    border: 1px solid rgba(126, 231, 255, 0.08);
    border-left: 2px solid rgba(126, 231, 255, 0.25);
    border-radius: 2px;
    margin-bottom: 14px;
    background: rgba(126, 231, 255, 0.015);
    transition: border-color 0.3s ease, background 0.3s ease, transform 0.3s ease;
}
.packet:hover {
    border-color: rgba(126, 231, 255, 0.3);
    border-left-color: var(--cyan);
    background: rgba(126, 231, 255, 0.04);
    transform: translateX(3px);
}
.packet a {
    color: inherit;
    text-decoration: none;
    display: block;
}
.packet .ts {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.72em;
    color: var(--text-faint);
    letter-spacing: 0.06em;
    text-transform: uppercase;
    margin-bottom: 8px;
}
.packet h3 {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 400;
    font-size: 1.05em;
    margin: 0 0 10px;
    color: var(--text);
}
.packet p {
    color: var(--text-dim);
    font-size: 0.9em;
    line-height: 1.65;
    margin: 0;
}
.packet .badge {
    display: inline-block;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.66em;
    padding: 2px 8px;
    border: 1px solid rgba(176, 140, 255, 0.35);
    color: var(--lavender);
    border-radius: 1px;
    margin-left: 8px;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    vertical-align: middle;
}

/* --- transmitter (deck only) --- */
.transmitter-area {
    position: relative;
    margin: 96px 0 32px;
    text-align: center;
    font-family: 'JetBrains Mono', monospace;
}
.transmitter-area .prompt {
    color: var(--text-faint);
    font-size: 0.78em;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    margin: 0 0 16px;
}
.transmitter {
    --glow: 0;
    position: relative;
    display: inline-block;
    width: 72px; height: 72px;
    background: transparent;
    border: none;
    padding: 0;
    color: var(--cyan);
    cursor: pointer;
    filter: drop-shadow(0 0 calc(var(--glow) * 1px) rgba(126, 231, 255, 0.55));
    transition: transform 0.18s ease, filter 0.4s ease;
}
.transmitter:hover { transform: scale(1.06); }
.transmitter:active { transform: scale(0.94); }
.transmitter svg { width: 100%; height: 100%; display: block; }
.transmitter .core {
    fill: var(--cyan);
    transition: fill 0.4s ease;
}
.transmitter.armed .core { fill: var(--warm); }
.transmitter.armed { color: var(--warm); }
.transmitter-area .status {
    margin: 18px 0 0;
    color: var(--text-dim);
    font-size: 0.85em;
    letter-spacing: 0.04em;
    min-height: 1.4em;
}
.transmitter-area .status .n {
    color: var(--lavender);
    margin-left: 8px;
}

/* pulse rings */
.pulse-ring {
    position: absolute;
    left: 50%; top: 50%;
    width: 72px; height: 72px;
    margin-left: -36px; margin-top: -36px;
    border: 1px solid var(--cyan);
    border-radius: 50%;
    pointer-events: none;
    opacity: 0;
    animation: ring-out 2.2s ease-out forwards;
}
.pulse-ring.warm { border-color: var(--warm); }
@keyframes ring-out {
    0%   { transform: scale(0.5); opacity: 0.85; }
    100% { transform: scale(5);   opacity: 0; }
}

/* --- footer --- */
.footer-note {
    margin-top: 80px;
    text-align: center;
    font-family: 'JetBrains Mono', monospace;
    color: var(--text-faint);
    font-size: 0.85em;
    letter-spacing: 0.04em;
}
.visit-tally {
    margin-top: 12px;
    text-align: center;
    font-family: 'JetBrains Mono', monospace;
    color: var(--text-faint);
    font-size: 0.72em;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}
.visit-tally .count { color: var(--cyan); }
.visit-tally .dim { color: var(--text-faint); opacity: 0.6; }

/* --- comet --- */
.comet {
    position: fixed;
    left: 0; top: 0;
    width: 3px; height: 3px;
    background: #fff;
    border-radius: 50%;
    z-index: 3;
    pointer-events: none;
    box-shadow:
        0 0 6px 1px #fff,
        0 0 18px 4px rgba(126, 231, 255, 0.6);
    will-change: transform;
}
.comet::after {
    content: '';
    position: absolute;
    right: 3px;
    top: 50%;
    margin-top: -0.5px;
    width: 70px;
    height: 1px;
    background: linear-gradient(to left, rgba(255,255,255,0.95), rgba(126,231,255,0.4) 40%, transparent);
    box-shadow: 0 0 4px rgba(126, 231, 255, 0.5);
    transform-origin: right center;
}

/* ============================================================
   blog post — used by  blogs/<slug>/index.html
   ============================================================ */

.post {
    max-width: 680px;
}

.post-meta {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78em;
    color: var(--text-faint);
    letter-spacing: 0.08em;
    text-transform: uppercase;
    margin-bottom: 16px;
}
.post-meta .sep { margin: 0 8px; opacity: 0.5; }
.post-meta .tag { color: var(--lavender); }

h1.post-title {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 500;
    font-size: 2em;
    color: var(--text);
    line-height: 1.25;
    margin: 0 0 48px;
    letter-spacing: -0.005em;
}

.post-body {
    font-family: 'Inter', -apple-system, sans-serif;
    font-size: 1em;
    line-height: 1.8;
    color: var(--text);
    font-weight: 300;
}

.post-body > p { margin: 0 0 1.4em; }

.post-body h2 {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 500;
    font-size: 1.25em;
    color: var(--cyan);
    margin: 56px 0 20px;
    letter-spacing: 0.02em;
}
.post-body h2::before {
    content: '// ';
    color: var(--text-faint);
}

.post-body h3 {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 400;
    font-size: 1.05em;
    color: var(--text);
    margin: 36px 0 14px;
}

.post-body a {
    color: var(--cyan);
    text-decoration: none;
    border-bottom: 1px dotted rgba(126, 231, 255, 0.45);
    transition: border-color 0.2s ease, text-shadow 0.2s ease;
}
.post-body a:hover {
    border-bottom-color: var(--cyan);
    text-shadow: 0 0 8px rgba(126, 231, 255, 0.5);
}

.post-body strong { color: var(--text); font-weight: 500; }
.post-body em { color: var(--lavender); font-style: italic; }

.post-body code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.88em;
    padding: 1px 6px;
    background: rgba(126, 231, 255, 0.07);
    border: 1px solid rgba(126, 231, 255, 0.14);
    border-radius: 2px;
    color: var(--cyan);
}

.post-body pre {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
    line-height: 1.6;
    padding: 16px 20px;
    background: rgba(10, 14, 46, 0.5);
    border: 1px solid rgba(126, 231, 255, 0.1);
    border-left: 2px solid rgba(126, 231, 255, 0.4);
    border-radius: 2px;
    overflow-x: auto;
    color: var(--text);
    margin: 1.6em 0;
}
.post-body pre code {
    background: none;
    border: none;
    padding: 0;
    color: inherit;
    font-size: inherit;
}

.post-body blockquote {
    border-left: 2px solid var(--lavender);
    padding: 6px 22px;
    margin: 1.6em 0;
    color: var(--text-dim);
    font-style: italic;
    background: rgba(176, 140, 255, 0.04);
}
.post-body blockquote p { margin: 0.5em 0; }

.post-body ul, .post-body ol {
    padding-left: 1.4em;
    margin: 0 0 1.4em;
}
.post-body li { margin-bottom: 0.4em; }
.post-body ul li::marker { color: var(--cyan); }
.post-body ol li::marker { color: var(--cyan); font-family: 'JetBrains Mono', monospace; }

.post-body img,
.post-body figure {
    max-width: 100%;
    margin: 1.8em auto;
    display: block;
}
.post-body figure { text-align: center; }
.post-body figure img { margin: 0 auto; }
.post-body figcaption {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78em;
    color: var(--text-faint);
    margin-top: 10px;
    letter-spacing: 0.04em;
}

.post-body hr {
    border: none;
    border-top: 1px dashed rgba(126, 231, 255, 0.15);
    margin: 3em 0;
}

.post-end {
    margin-top: 80px;
    text-align: center;
    font-family: 'JetBrains Mono', monospace;
    color: var(--text-faint);
    font-size: 0.85em;
    letter-spacing: 0.06em;
}

/* --- math (KaTeX) — inherits .post-body color (light on dark) --- */
.post-body .katex { color: inherit; }
.post-body .katex-display {
    margin: 1.6em 0;
    overflow-x: auto;
    overflow-y: hidden;
    padding: 4px 0;
}

/* ============================================================
   bilingual toggle  (CN / EN)
   set html.lang-en or html.lang-zh on <html> to control visibility;
   each translatable element gets data-lang="en" or data-lang="zh"
   ============================================================ */

html.lang-en [data-lang="zh"] { display: none; }
html.lang-zh [data-lang="en"] { display: none; }

.lang-toggle {
    margin-left: auto;
    display: flex;
    align-items: center;
    gap: 6px;
}
.lang-toggle .label {
    color: var(--text-faint);
}
.lang-toggle button {
    background: none;
    border: none;
    padding: 0;
    margin: 0;
    color: var(--text-faint);
    font-family: inherit;
    font-size: inherit;
    letter-spacing: inherit;
    text-transform: inherit;
    cursor: pointer;
    transition: color 0.2s ease, text-shadow 0.2s ease;
}
.lang-toggle button:hover {
    color: var(--text-dim);
}
.lang-toggle button.active {
    color: var(--cyan);
    text-shadow: 0 0 6px rgba(126, 231, 255, 0.5);
}
.lang-toggle .divider {
    color: var(--text-faint);
    opacity: 0.5;
}

/* --- responsive + reduced motion --- */
@media (max-width: 560px) {
    h1.hero { font-size: 1.7em; }
    .deck { padding: 24px 20px 100px; }
    .status-bar { font-size: 0.62em; gap: 12px; }
    h1.post-title { font-size: 1.5em; }
    .post-body { font-size: 0.95em; }
}

@media (prefers-reduced-motion: reduce) {
    .star, .status-bar .live::before, .comet { animation: none; }
    .pulse-ring { animation-duration: 1ms; }
}