:root {
    --blue: #0a5ae6;
    --blue-2: #3aa0ff;
    --ink: #1c1c1e;
    --muted: #6b7280;
    --line: #e5e7eb;
    --bg: #ffffff;
    --card: #f7f8fa;
    color-scheme: light;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC",
        "Microsoft JhengHei", system-ui, sans-serif;
    color: var(--ink);
    background: var(--bg);
    line-height: 1.65;
}

/* 語言切換：預設英文 */
.zh { display: none; }
.lang-zh .zh { display: revert; }
.lang-zh .en { display: none; }

a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap { max-width: 880px; margin: 0 auto; padding: 0 24px; }

/* 導覽列 */
header.nav {
    position: sticky; top: 0; z-index: 10;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: saturate(180%) blur(12px);
    border-bottom: 1px solid var(--line);
}
.nav .wrap { display: flex; align-items: center; gap: 16px; height: 60px; }
.nav .brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 18px; }
.nav .brand img { width: 30px; height: 30px; border-radius: 7px; }
.nav .spacer { flex: 1; }
.nav a.link { color: var(--ink); font-size: 15px; }
.langswitch { display: inline-flex; border: 1px solid var(--line); border-radius: 999px; overflow: hidden; }
.langswitch button {
    border: 0; background: transparent; padding: 6px 12px; cursor: pointer;
    font-size: 13px; color: var(--muted);
}
.lang-en .langswitch .b-en, .lang-zh .langswitch .b-zh { background: var(--blue); color: #fff; }

/* Hero */
.hero {
    background: linear-gradient(160deg, var(--blue-2), var(--blue));
    color: #fff; text-align: center; padding: 72px 24px 80px;
}
.hero img.logo { width: 108px; height: 108px; border-radius: 24px; box-shadow: 0 12px 40px rgba(0,0,0,.25); }
.hero h1 { font-size: 44px; margin: 20px 0 6px; letter-spacing: -0.5px; }
.hero p.tag { font-size: 20px; opacity: .95; margin: 0 auto 26px; max-width: 560px; }
.btn {
    display: inline-block; background: #fff; color: var(--blue);
    font-weight: 600; padding: 13px 26px; border-radius: 999px; font-size: 16px;
}
.btn:hover { text-decoration: none; opacity: .92; }

/* 內容區塊 */
section.block { padding: 56px 0; }
section.block h2 { font-size: 28px; margin: 0 0 8px; letter-spacing: -0.3px; }
.lead { color: var(--muted); margin-top: 0; }

.features { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 28px; }
.feature { background: var(--card); border: 1px solid var(--line); border-radius: 16px; padding: 22px; }
.feature .ico { font-size: 28px; }
.feature h3 { margin: 10px 0 6px; font-size: 18px; }
.feature p { margin: 0; color: var(--muted); font-size: 15px; }

/* 文件頁 */
.doc { padding: 44px 24px 80px; }
.doc h1 { font-size: 34px; margin: 0 0 4px; }
.doc h2 { font-size: 22px; margin: 34px 0 10px; padding-top: 8px; }
.doc h3 { font-size: 17px; margin: 22px 0 6px; }
.doc p, .doc li { color: #33353a; }
.doc .updated { color: var(--muted); font-size: 14px; }
.doc code, .copyfield {
    font-family: ui-monospace, "SF Mono", Menlo, monospace;
    background: var(--card); border: 1px solid var(--line); border-radius: 6px; padding: 2px 6px;
}
.copyfield {
    display: block; padding: 12px 14px; margin: 6px 0 16px; white-space: pre-wrap;
    font-size: 14px; line-height: 1.6;
}
.label { font-weight: 600; margin-top: 18px; }
ol.steps { padding-left: 20px; }
ol.steps > li { margin: 10px 0; }
.note { background: #eef4ff; border: 1px solid #cfe0ff; border-radius: 12px; padding: 14px 16px; margin: 18px 0; font-size: 15px; }

footer.foot { border-top: 1px solid var(--line); padding: 30px 0 50px; color: var(--muted); font-size: 14px; }
footer.foot .wrap { display: flex; flex-wrap: wrap; gap: 10px 24px; align-items: center; }
footer.foot .spacer { flex: 1; }

@media (max-width: 720px) {
    .features { grid-template-columns: 1fr; }
    .hero { padding: 56px 20px 60px; }
    .hero h1 { font-size: 34px; }
    .nav a.link.hide-sm { display: none; }
    .wrap { padding: 0 20px; }
    .doc { padding: 32px 20px 64px; }
    .doc h1 { font-size: 28px; }
    .doc h2 { font-size: 20px; }
    .copyfield { font-size: 13px; }
}