/* BackToWin site — dark, professional, zero dependencies */
:root {
  --bg: #0b0f14; --bg2: #0f1520; --card: #131b26; --card2: #16202e;
  --line: #1f2b3a; --txt: #e6edf3; --mut: #8b98a9;
  --acc: #4f8cff; --acc2: #2dd4bf; --warn: #f59e0b;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg); color: var(--txt);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial,
    "PingFang SC", "Microsoft YaHei", sans-serif;
  line-height: 1.65; font-size: 16px;
}
a { color: var(--acc); text-decoration: none; }
a:hover { text-decoration: underline; }
.wrap { max-width: 1080px; margin: 0 auto; padding: 0 24px; }

/* nav */
nav {
  position: sticky; top: 0; z-index: 10;
  background: rgba(11, 15, 20, .92); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
nav .wrap { display: flex; align-items: center; gap: 28px; height: 60px; }
.logo { font-weight: 700; font-size: 18px; color: var(--txt); letter-spacing: .2px; }
.logo b { color: var(--acc2); }
nav .links { margin-left: auto; display: flex; gap: 22px; }
nav .links a { color: var(--mut); font-size: 14.5px; }
nav .links a:hover { color: var(--txt); text-decoration: none; }
nav .cta {
  background: var(--acc); color: #fff; padding: 7px 14px; border-radius: 8px;
  font-size: 14px; font-weight: 600;
}
nav .cta:hover { text-decoration: none; filter: brightness(1.1); }

/* hero */
.hero { padding: 84px 0 56px; text-align: center; }
.hero h1 { font-size: 44px; line-height: 1.2; letter-spacing: -.5px; max-width: 820px; margin: 0 auto; }
.hero h1 span { color: var(--acc2); }
.hero p.sub { color: var(--mut); font-size: 18px; max-width: 640px; margin: 18px auto 0; }
.hero .btns { margin-top: 32px; display: flex; gap: 14px; justify-content: center; }
.btn {
  display: inline-block; padding: 12px 26px; border-radius: 10px; font-weight: 600; font-size: 15.5px;
}
.btn.primary { background: var(--acc); color: #fff; }
.btn.ghost { border: 1px solid var(--line); color: var(--txt); background: var(--card); }
.btn:hover { text-decoration: none; filter: brightness(1.1); }
.pilot {
  display: inline-block; margin-top: 26px; font-size: 12.5px; color: var(--mut);
  border: 1px solid var(--line); border-radius: 999px; padding: 4px 14px;
}

/* sections */
section { padding: 64px 0; border-top: 1px solid var(--line); }
section h2 { font-size: 30px; letter-spacing: -.3px; margin-bottom: 10px; }
section p.lead { color: var(--mut); max-width: 720px; margin-bottom: 36px; }
.grid3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.grid2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
@media (max-width: 860px) { .grid3, .grid2 { grid-template-columns: 1fr; } .hero h1 { font-size: 32px; } }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 26px;
}
.card h3 { font-size: 17.5px; margin-bottom: 8px; }
.card p { color: var(--mut); font-size: 14.8px; }
.card .ico { font-size: 24px; margin-bottom: 12px; display: block; }

/* steps */
.step { display: flex; gap: 18px; align-items: flex-start; }
.step .num {
  flex: 0 0 40px; height: 40px; border-radius: 10px; background: var(--card2);
  border: 1px solid var(--line); color: var(--acc2); font-weight: 700;
  display: flex; align-items: center; justify-content: center;
}

/* risk callout */
.risk {
  background: linear-gradient(180deg, var(--card), var(--bg2));
  border: 1px solid var(--line); border-left: 3px solid var(--warn);
  border-radius: 14px; padding: 26px 28px;
}
.risk h3 { font-size: 18px; margin-bottom: 8px; }
.risk p { color: var(--mut); font-size: 15px; }

/* pricing */
.price { text-align: center; position: relative; }
.price .tag {
  position: absolute; top: -12px; left: 50%; transform: translateX(-50%);
  background: var(--acc2); color: #06251f; font-size: 12px; font-weight: 700;
  padding: 3px 12px; border-radius: 999px;
}
.price .amount { font-size: 34px; font-weight: 700; margin: 6px 0 2px; }
.price .amount small { font-size: 15px; color: var(--mut); font-weight: 400; }
.price ul { list-style: none; margin-top: 14px; }
.price ul li { color: var(--mut); font-size: 14.5px; padding: 4px 0; }

/* code blocks */
.code {
  background: #0a0e13; border: 1px solid var(--line); border-radius: 10px;
  padding: 16px 18px; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 13.5px; color: #cfe3ff; overflow-x: auto; position: relative; white-space: pre;
}
.code .copy {
  position: absolute; top: 8px; right: 8px; background: var(--card2); color: var(--mut);
  border: 1px solid var(--line); border-radius: 6px; font-size: 12px; padding: 3px 10px; cursor: pointer;
}
.code .copy:hover { color: var(--txt); }

/* faq */
.faq details {
  background: var(--card); border: 1px solid var(--line); border-radius: 12px;
  padding: 16px 20px; margin-bottom: 10px;
}
.faq summary { cursor: pointer; font-weight: 600; font-size: 15.5px; }
.faq details p { color: var(--mut); font-size: 14.8px; margin-top: 10px; }

/* table */
table.tools { width: 100%; border-collapse: collapse; font-size: 14.5px; }
table.tools th, table.tools td {
  text-align: left; padding: 10px 14px; border-bottom: 1px solid var(--line); vertical-align: top;
}
table.tools th { color: var(--mut); font-weight: 600; }
table.tools td:first-child { font-family: ui-monospace, Menlo, Consolas, monospace; color: var(--acc2); white-space: nowrap; }
table.tools td:last-child { color: var(--mut); }

/* cta + footer */
.cta-big { text-align: center; padding: 72px 0; }
.cta-big h2 { font-size: 30px; margin-bottom: 20px; }
footer { border-top: 1px solid var(--line); padding: 36px 0 48px; color: var(--mut); font-size: 13.5px; }
footer .cols { display: flex; gap: 48px; flex-wrap: wrap; margin-bottom: 24px; }
footer .cols a { display: block; color: var(--mut); padding: 3px 0; }
footer .cols a:hover { color: var(--txt); text-decoration: none; }
footer .cols b { color: var(--txt); display: block; margin-bottom: 8px; font-size: 14px; }

/* stats page */
.stat-big { font-size: 40px; font-weight: 700; color: var(--acc2); }
.stat-lbl { color: var(--mut); font-size: 14px; }
.muted-note { color: var(--mut); font-size: 13.5px; margin-top: 8px; }
.ok-badge { color: var(--acc2); font-weight: 600; }
.bad-badge { color: var(--warn); font-weight: 600; }

/* language switcher */
.langsw { margin-left: auto; display: flex; gap: 10px; align-items: center; }
.langsw a.lang { color: var(--mut); font-size: 13px; padding: 3px 8px; border-radius: 6px; border: 1px solid transparent; }
.langsw a.lang:hover { color: var(--txt); text-decoration: none; border-color: var(--line); }
.langsw a.lang.cur { color: var(--acc2); border-color: var(--line); font-weight: 600; }
nav .wrap nav .langsw { margin-left: auto; }

/* [黑盒P1修复] 375px 移动端: 导航不溢出, 语言切换器保持首屏可达 */
@media (max-width: 960px) {
  nav .links { display: none; }
}
@media (max-width: 640px) {
  nav .wrap { gap: 10px; height: auto; flex-wrap: nowrap; padding: 8px 14px; }
  .logo { font-size: 16px; }
  .langsw { gap: 4px; }
  .langsw a.lang { padding: 2px 5px; font-size: 11.5px; }
  nav .cta { padding: 6px 9px; font-size: 12.5px; }
  .hero { padding: 48px 0 36px; }
  .hero h1 { font-size: 26px; }
  .hero p.sub { font-size: 15px; }
  .btns { flex-wrap: wrap; }
  section { padding: 44px 0; }
}