:root {
  --bg: #0b0d12;
  --bg-soft: #11141b;
  --panel: #151922;
  --border: #242a36;
  --text: #e7e9ee;
  --text-dim: #9aa3b2;
  --brand: #5b8cff;
  --brand-2: #7ee0c3;
  --danger: #ff6b6b;
  --warn: #ffc400;
  --nav-bg: rgba(11, 13, 18, 0.85);
  --radius: 14px;
  --max-width: 1080px;
  color-scheme: dark;
}

:root[data-theme="light"] {
  --bg: #f7f8fb;
  --bg-soft: #ffffff;
  --panel: #ffffff;
  --border: #e3e7ef;
  --text: #171a21;
  --text-dim: #5c6373;
  --brand: #3f6fe0;
  --brand-2: #0f9d72;
  --danger: #d6455a;
  --warn: #a8710a;
  --nav-bg: rgba(255, 255, 255, 0.85);
  color-scheme: light;
}

/* 无 JS 环境下的渐进增强：跟随系统偏好 */
@media (prefers-color-scheme: light) {
  :root:not([data-theme]) {
    --bg: #f7f8fb;
    --bg-soft: #ffffff;
    --panel: #ffffff;
    --border: #e3e7ef;
    --text: #171a21;
    --text-dim: #5c6373;
    --brand: #3f6fe0;
    --brand-2: #0f9d72;
    --danger: #d6455a;
    --warn: #a8710a;
    --nav-bg: rgba(255, 255, 255, 0.85);
    color-scheme: light;
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei",
    "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.2s ease, color 0.2s ease;
}

a { color: inherit; }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* 顶部导航 */
.nav {
  position: sticky;
  top: 0;
  z-index: 20;
  background: var(--nav-bg);
  backdrop-filter: saturate(150%) blur(8px);
  border-bottom: 1px solid var(--border);
}
.nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  gap: 12px;
}
.nav .logo {
  font-weight: 700;
  font-size: 18px;
  letter-spacing: 0.5px;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}
.nav .logo .dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  display: inline-block;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  font-size: 14px;
  color: var(--text-dim);
  flex: 1;
  justify-content: center;
}
.nav-links a { text-decoration: none; }
.nav-links a:hover { color: var(--text); }

.nav-right {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  cursor: pointer;
  font-size: 16px;
  line-height: 1;
  padding: 0;
}
.icon-btn:hover { border-color: var(--text-dim); }
.icon-btn .icon-sun { display: none; }
.icon-btn .icon-moon { display: inline; }
:root[data-theme="light"] .icon-btn .icon-sun { display: inline; }
:root[data-theme="light"] .icon-btn .icon-moon { display: none; }

.lang-switch {
  display: flex;
  align-items: center;
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  font-size: 13px;
  font-weight: 600;
  flex-shrink: 0;
}
.lang-switch a {
  padding: 8px 12px;
  text-decoration: none;
  color: var(--text-dim);
  background: var(--panel);
  white-space: nowrap;
}
.lang-switch a.active {
  color: #fff;
  background: linear-gradient(135deg, var(--brand), #3f6fe0);
}

.nav .cta {
  padding: 9px 18px;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--brand), #3f6fe0);
  color: #fff !important;
  text-decoration: none;
  font-size: 14px;
  font-weight: 600;
  white-space: nowrap;
  flex-shrink: 0;
}

.nav-toggle {
  display: none;
  width: 38px;
  height: 38px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--panel);
  cursor: pointer;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  flex-shrink: 0;
}
.nav-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
}

@media (max-width: 860px) {
  .nav-links {
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: flex-start;
    gap: 2px;
    background: var(--bg-soft);
    border-bottom: 1px solid var(--border);
    padding: 8px 20px 16px;
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    pointer-events: none;
    transition: max-height 0.2s ease, opacity 0.15s ease;
  }
  .nav-links.is-open {
    max-height: 400px;
    opacity: 1;
    pointer-events: auto;
  }
  .nav-links a {
    width: 100%;
    padding: 12px 0;
    border-bottom: 1px solid var(--border);
    color: var(--text);
  }
  .nav-links a:last-child { border-bottom: none; }
  .nav-toggle { display: flex; }
  .nav .cta { display: none; }
}

@media (max-width: 480px) {
  .lang-switch a { padding: 7px 9px; }
}

/* Hero */
.hero {
  padding: 72px 0 56px;
  text-align: center;
  background:
    radial-gradient(60% 50% at 50% 0%, color-mix(in srgb, var(--brand) 16%, transparent), transparent 70%);
}
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--brand-2);
  background: color-mix(in srgb, var(--brand-2) 10%, transparent);
  border: 1px solid color-mix(in srgb, var(--brand-2) 28%, transparent);
  padding: 6px 14px;
  border-radius: 999px;
  margin-bottom: 22px;
}
.hero h1 {
  font-size: clamp(28px, 5.2vw, 44px);
  line-height: 1.32;
  margin: 0 0 18px;
  font-weight: 800;
  letter-spacing: -0.5px;
}
.hero h1 .accent {
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero p.lead {
  max-width: 680px;
  margin: 0 auto 34px;
  color: var(--text-dim);
  font-size: clamp(15px, 2vw, 17px);
}
.hero-actions {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
}
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  min-height: 48px;
  border-radius: 10px;
  font-weight: 600;
  font-size: 15px;
  text-decoration: none;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.btn-primary {
  background: linear-gradient(135deg, var(--brand), #3f6fe0);
  color: #fff;
  box-shadow: 0 8px 24px color-mix(in srgb, var(--brand) 32%, transparent);
}
.btn-primary:hover { transform: translateY(-1px); }
.btn-ghost {
  background: transparent;
  border-color: var(--border);
  color: var(--text);
}
.btn-ghost:hover { border-color: var(--text-dim); }
.btn-block { width: 100%; }

/* Section 通用 */
.section { padding: 56px 0; border-top: 1px solid var(--border); }
.section .eyebrow {
  font-size: 13px;
  letter-spacing: 1px;
  text-transform: uppercase;
  color: var(--brand-2);
  margin-bottom: 10px;
  font-weight: 700;
}
.section h2 {
  font-size: clamp(22px, 3.2vw, 28px);
  margin: 0 0 12px;
  font-weight: 800;
}
.section p.desc { color: var(--text-dim); max-width: 680px; margin: 0 0 32px; }

/* 卡片网格 */
.grid { display: grid; gap: 18px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 900px) {
  .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 600px) {
  .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
}
.card h3 { margin: 0 0 8px; font-size: 16px; }
.card p { margin: 0; color: var(--text-dim); font-size: 14px; }
.card .tag {
  display: inline-block;
  font-size: 12px;
  color: var(--brand-2);
  background: color-mix(in srgb, var(--brand-2) 10%, transparent);
  border: 1px solid color-mix(in srgb, var(--brand-2) 22%, transparent);
  padding: 2px 8px;
  border-radius: 6px;
  margin-bottom: 10px;
}

/* 表格 */
.table-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius); -webkit-overflow-scrolling: touch; }
table { width: 100%; border-collapse: collapse; font-size: 14px; min-width: 560px; }
thead th {
  text-align: left;
  background: var(--bg-soft);
  color: var(--text-dim);
  font-weight: 600;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}
tbody td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  vertical-align: top;
}
tbody tr:last-child td { border-bottom: none; }
td.dim, th.dim { color: var(--text-dim); }

/* 适合谁 / 列表 */
.list-check { list-style: none; margin: 0; padding: 0; display: grid; gap: 12px; }
.list-check li {
  display: flex;
  gap: 10px;
  color: var(--text-dim);
  font-size: 14.5px;
}
.list-check li::before {
  content: "✓";
  color: var(--brand-2);
  font-weight: 700;
  flex-shrink: 0;
}
.list-check strong { color: var(--text); }

/* CTA 区块 */
.cta-panel {
  background: linear-gradient(135deg, color-mix(in srgb, var(--brand) 14%, transparent), color-mix(in srgb, var(--brand-2) 10%, transparent));
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 44px 24px;
  text-align: center;
}
.cta-panel h2 { margin: 0 0 10px; font-size: clamp(20px, 3vw, 26px); }
.cta-panel p { color: var(--text-dim); margin: 0 0 26px; }

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 32px 0 48px;
  color: var(--text-dim);
  font-size: 13px;
}
footer .container {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}
footer a { color: var(--text-dim); text-decoration: none; }
footer a:hover { color: var(--text); }

/* 表单页 */
.form-page { padding: 56px 0; }
.form-shell {
  max-width: 560px;
  margin: 0 auto;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
}
.form-shell h1 { font-size: clamp(20px, 3vw, 24px); margin: 0 0 6px; }
.form-shell p.hint { color: var(--text-dim); font-size: 14px; margin: 0 0 26px; }

.field { margin-bottom: 18px; }
.field label {
  display: block;
  font-size: 13.5px;
  color: var(--text-dim);
  margin-bottom: 6px;
}
.field input[type="text"],
.field input[type="email"],
.field input[type="tel"],
.field textarea {
  width: 100%;
  padding: 12px 14px;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--text);
  font-size: 16px;
  font-family: inherit;
  outline: none;
  transition: border-color 0.15s ease;
}
.field input:focus, .field textarea:focus { border-color: var(--brand); }
.field textarea { resize: vertical; min-height: 110px; }

.captcha-row { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.captcha-row .captcha-q {
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 16px;
  font-weight: 700;
  font-size: 16px;
  letter-spacing: 1px;
  white-space: nowrap;
  user-select: none;
}
.captcha-row input { flex: 1; min-width: 140px; }

/* honeypot 字段：对正常用户隐藏，但依然存在于 DOM 中供机器人填写 */
.hp-field {
  position: absolute;
  left: -9999px;
  top: -9999px;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

.alert {
  border-radius: 10px;
  padding: 14px 16px;
  font-size: 14px;
  margin-bottom: 22px;
  border: 1px solid transparent;
}
.alert-success {
  background: color-mix(in srgb, var(--brand-2) 12%, transparent);
  border-color: color-mix(in srgb, var(--brand-2) 30%, transparent);
  color: var(--brand-2);
}
.alert-error {
  background: color-mix(in srgb, var(--danger) 12%, transparent);
  border-color: color-mix(in srgb, var(--danger) 30%, transparent);
  color: var(--danger);
}
.alert-warn {
  background: color-mix(in srgb, var(--warn) 14%, transparent);
  border-color: color-mix(in srgb, var(--warn) 32%, transparent);
  color: var(--warn);
}

.field-error { color: var(--danger); font-size: 12.5px; margin-top: 6px; }

@media (max-width: 640px) {
  .form-shell { padding: 24px 18px; }
  .cta-panel { padding: 32px 18px; }
  .section { padding: 44px 0; }
}