/* ─────────────────────────────────────────────
   global.css — shared tokens and components
   Loaded on every page before page-specific CSS
───────────────────────────────────────────── */

:root {
    --bg:       #FFFFFF;
    --bg-up:    #F8FAFC;
    --text:     #1A1A1A;
    --muted:    #71717A;
    --accent:   #38BDF8;
    --gold:     #D97706;
    --border:   rgba(0, 0, 0, 0.08);
    --overlay:  rgba(255, 255, 255, 0.88);
    --sans:     'Inter', sans-serif;
    --mono:     'IBM Plex Mono', monospace;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
    background: var(--bg);
    color: var(--text);
    font-family: var(--sans);
    line-height: 1.6;
}

/* ── Page fade-in ── */
@keyframes pageFadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* ── Canvas background ── */
#matrix-bg {
    position: fixed;
    inset: 0;
    width: 100%; height: 100%;
    z-index: 0;
    pointer-events: none;
}

/* ── Nav ── */
nav {
    position: sticky; top: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.88);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    padding: 0 40px;
}
.nav-inner {
    max-width: 1100px; margin: 0 auto;
    display: flex; align-items: center; justify-content: space-between;
    height: 56px;
}
.nav-logo {
    font-family: var(--sans); font-size: 17px; font-weight: 700;
    color: var(--text); text-decoration: none;
    letter-spacing: -0.02em;
}
.nav-back {
    font-family: var(--mono); font-size: 12px;
    color: var(--muted); text-decoration: none;
    letter-spacing: -0.02em; transition: color 0.2s;
}
.nav-back:hover { color: var(--accent); }
.lang-btn {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--muted);
    padding: 5px 14px; border-radius: 6px;
    cursor: pointer; font-family: var(--mono);
    font-size: 12px; letter-spacing: -0.01em;
    transition: all 0.2s;
}
.lang-btn:hover,
.lang-btn[aria-pressed="true"] { border-color: var(--accent); color: var(--accent); }

/* ── Canvas toggle ── */
.canvas-toggle {
    position: fixed; bottom: 20px; right: 40px;
    background: rgba(255, 255, 255, 0.92);
    border: 1px solid var(--border);
    color: var(--muted);
    padding: 6px 14px; border-radius: 6px;
    cursor: pointer; font-family: var(--mono);
    font-size: 11px; z-index: 10;
    transition: all 0.2s;
    backdrop-filter: blur(10px);
    letter-spacing: -0.01em;
}
.canvas-toggle:hover { border-color: var(--accent); color: var(--accent); }

/* ── Back to Top ── */
.back-to-top {
    position: fixed; bottom: 40px;
    left: 50%; transform: translateX(-50%) translateY(8px);
    padding: 8px 24px;
    background: rgba(255, 255, 255, 0.7);
    border: 1px solid var(--border);
    color: var(--muted);
    border-radius: 6px;
    cursor: pointer; font-family: var(--mono);
    font-size: 11px; letter-spacing: 0.06em;
    z-index: 10;
    display: flex; align-items: center; justify-content: center; gap: 6px;
    white-space: nowrap;
    opacity: 0; pointer-events: none;
    transition: opacity 0.3s ease, transform 0.3s ease,
                border-color 0.2s, color 0.2s;
    backdrop-filter: blur(10px);
}
.back-to-top.visible {
    opacity: 1;
    pointer-events: auto;
    transform: translateX(-50%) translateY(0);
}
.back-to-top:hover { border-color: var(--accent); color: var(--accent); }

/* ── Lang toggle ── */
[lang="zh"] { display: none; }
.lang-zh [lang="en"] { display: none; }
.lang-zh [lang="zh"] { display: block; }
.lang-zh span[lang="zh"] { display: inline; }

/* ── Focus states ── */
a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 3px;
    border-radius: 3px;
}

/* ── 600px: hide canvas toggle on mobile ── */
@media (max-width: 600px) {
    .canvas-toggle { display: none; }
}

/* ── 480px: mobile nav padding ── */
@media (max-width: 480px) {
    nav { padding: 0 24px; }
}