/*
  The design system: the tokens, the page frame, the sticky header, the pill
  buttons and the footer — everything shared across the site's four screens.

  Loaded by index.html, which is the whole site, and also by czzy/feed.xsl, whose
  only job is to bounce a browser from the feed URL to /#/podcast. Linking this
  file there means that one-line page wears the site's chrome for free.
*/

:root {
    --bg: #ffffff;
    --text: #1a1a1a;
    --muted: #6b6b6b;
    --accent: #1a1a1a;
    --line: #ececec;
    --maxw: 880px;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #111111;
        --text: #ededed;
        --muted: #9a9a9a;
        --accent: #ffffff;
        --line: #262626;
    }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
    font-size: 18px;
    line-height: 1.65;
    -webkit-font-smoothing: antialiased;
}

.wrap {
    max-width: var(--maxw);
    margin: 0 auto;
    padding: 0 24px;
}

/* Header */
header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: color-mix(in srgb, var(--bg) 88%, transparent);
    backdrop-filter: saturate(180%) blur(12px);
    -webkit-backdrop-filter: saturate(180%) blur(12px);
    border-bottom: 1px solid var(--line);
}
.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.brand {
    font-weight: 800;
    font-size: 20px;
    letter-spacing: -0.01em;
    color: var(--text);
    text-decoration: none;
}

nav { display: flex; align-items: center; }
nav a {
    color: var(--muted);
    text-decoration: none;
    font-size: 15px;
    font-weight: 500;
    margin-left: 28px;
    transition: color 0.15s ease;
}
nav a:hover { color: var(--text); }
nav a.active { color: var(--text); font-weight: 600; }

/* Hero — the shared part: both pages open with a centered image, title and subtitle */
.hero {
    text-align: center;
    border-bottom: 1px solid var(--line);
}
.hero h1 {
    font-size: 46px;
    line-height: 1.12;
    letter-spacing: -0.03em;
    margin: 0 0 18px;
    font-weight: 800;
}

/* Pill buttons: the hero calls to action, and the podcast's 收听平台 links */
.btn {
    display: inline-block;
    text-decoration: none;
    font-size: 15px;
    font-weight: 600;
    padding: 12px 22px;
    border-radius: 999px;
    transition: opacity 0.15s ease, background 0.15s ease;
}
.btn-primary { background: var(--accent); color: var(--bg); }
.btn-primary:hover { opacity: 0.85; }
.btn-ghost { border: 1px solid var(--line); color: var(--text); }
.btn-ghost:hover { background: var(--line); }

/* Section heading above a list — 近期笔记 on the site, 全部单集 on the podcast */
.intro { padding: 56px 0 8px; }
.intro h1, .intro h2 {
    font-size: 36px;
    line-height: 1.15;
    letter-spacing: -0.03em;
    margin: 0;
    font-weight: 800;
}

/* Date · category line above a post or an episode */
.meta {
    font-size: 13px;
    letter-spacing: 0.04em;
    color: var(--muted);
    margin-bottom: 8px;
}

footer {
    padding: 32px 0 56px;
    color: var(--muted);
    font-size: 14px;
}
footer a { color: var(--muted); text-decoration: none; }
footer a:hover { color: var(--text); }

@media (max-width: 600px) {
    .hero h1 { font-size: 34px; }
}