/* =========================================================================
   Fy-AI (飞鱼) 前端设计系统 —— 全局主题变量 / 卡片 / 按钮 / 输入 / 动效
   两套主题：venom(毒液) / flat(扁平柔和渐变)
   全站（落地页 / 登录注册 / 控制台）共用，保证视觉语言统一。
   ========================================================================= */

/* ---------- Flat Soft Gradient（默认）---------- */
:root{
  --c-bg:#f7f8fc;
  --c-bg-grad:linear-gradient(160deg,#eef2ff 0%,#f7f8fc 40%,#fdf2f8 100%);
  --c-surface:#ffffff;
  --c-surface-2:#fafbff;
  --c-border:#e6e9f2;
  --c-text:#1a1d29;
  --c-text-2:#5b6172;
  --c-text-3:#8a90a2;
  --c-primary:#6366f1;
  --c-primary-2:#8b5cf6;
  --c-primary-soft:#eef0ff;
  --c-accent:#06b6d4;
  --c-success:#10b981;
  --c-warn:#f59e0b;
  --c-danger:#ef4444;
  --grad:linear-gradient(135deg,#6366f1 0%,#8b5cf6 100%);

  --radius:18px;
  --radius-sm:12px;
  --radius-lg:26px;
  --shadow:0 4px 20px rgba(99,102,241,.07),0 1px 3px rgba(16,24,40,.04);
  --shadow-hover:0 14px 40px rgba(99,102,241,.15),0 2px 8px rgba(16,24,40,.06);
  --ring:rgba(99,102,241,.35);
  --card-bg:rgba(255,255,255,.78);
  --card-blur:blur(14px);
}

/* ---------- Venom（毒液：暗黑 / 高对比 / 流体入侵感）---------- */
[data-theme="venom"]{
  --c-bg:#05070a;
  --c-bg-grad:
    radial-gradient(1000px 560px at 82% -14%, rgba(127,29,255,.30) 0%, transparent 58%),
    radial-gradient(760px 460px at 6% 108%, rgba(220,20,60,.22) 0%, transparent 60%),
    radial-gradient(620px 400px at 50% 46%, rgba(0,229,255,.10) 0%, transparent 60%),
    #05070a;
  --c-surface:#0b0e13;
  --c-surface-2:#0e1219;
  --c-border:#1b2130;
  --c-text:#e9fbf3;
  --c-text-2:#8fa6a0;
  --c-text-3:#5d7269;
  --c-primary:#a855f7;
  --c-primary-2:#22d3ee;
  --c-primary-soft:#150f22;
  --c-accent:#22d3ee;
  --c-success:#39ff14;
  --c-warn:#fbbf24;
  --c-danger:#f43f5e;
  --grad:linear-gradient(135deg,#7c1dff 0%,#22d3ee 100%);

  --radius:18px;
  --radius-sm:12px;
  --radius-lg:26px;
  --shadow:0 8px 30px rgba(0,0,0,.5),0 0 0 1px rgba(168,85,247,.10);
  --shadow-hover:0 0 0 1px rgba(168,85,247,.45),0 18px 46px rgba(0,0,0,.65);
  --ring:rgba(168,85,247,.5);
  --card-bg:rgba(11,14,19,.72);
  --card-blur:blur(16px);
}

/* ---------- 基础 ---------- */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  font-family:"Inter","PingFang SC","Microsoft YaHei",system-ui,-apple-system,sans-serif;
  background:var(--c-bg);background-image:var(--c-bg-grad);
  background-attachment:fixed;color:var(--c-text);
  line-height:1.6;-webkit-font-smoothing:antialiased;
  transition:background .35s ease,color .35s ease;
}
a{color:inherit;text-decoration:none}
button{font-family:inherit;cursor:pointer;border:none;background:none}
input,select,textarea{font-family:inherit;font-size:inherit}
ul{list-style:none}

.container{max-width:1180px;margin:0 auto;padding:0 24px}

/* ---------- 卡片：全站统一交互语言 ---------- */
.card{
  background:var(--card-bg);
  backdrop-filter:var(--card-blur);-webkit-backdrop-filter:var(--card-blur);
  border:1px solid var(--c-border);
  border-radius:var(--radius);
  box-shadow:var(--shadow);
  padding:26px;
  transition:transform .28s cubic-bezier(.22,1,.36,1),box-shadow .28s,border-color .28s;
}
.card:hover{
  transform:translateY(-3px);
  box-shadow:var(--shadow-hover);
  border-color:color-mix(in srgb,var(--c-primary) 35%,transparent);
}
.card-flat{background:var(--c-surface)}
.card-pad-sm{padding:18px}

/* 毒液：卡片的"粘稠/共生体"质感 */
[data-theme="venom"] .card{
  position:relative;overflow:hidden;
}
[data-theme="venom"] .card::after{
  content:"";position:absolute;inset:0;border-radius:inherit;pointer-events:none;
  background:radial-gradient(340px 160px at 100% 0%,rgba(168,85,247,.16),transparent 62%);
  opacity:.9;transition:opacity .3s;
}
[data-theme="venom"] .card:hover::after{opacity:1}

/* ---------- 按钮 ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:12px 24px;border-radius:var(--radius-sm);
  font-size:15px;font-weight:600;letter-spacing:.2px;
  transition:transform .22s cubic-bezier(.22,1,.36,1),box-shadow .22s,filter .22s,background .22s;
  position:relative;overflow:hidden;
}
.btn:active{transform:scale(.975)}
.btn-primary{
  background:var(--grad);color:#fff;
  box-shadow:0 6px 20px color-mix(in srgb,var(--c-primary) 34%,transparent);
}
.btn-primary:hover{transform:translateY(-2px);filter:brightness(1.07);
  box-shadow:0 12px 30px color-mix(in srgb,var(--c-primary) 46%,transparent)}
.btn-ghost{
  background:var(--c-surface);color:var(--c-text);
  border:1px solid var(--c-border);
}
.btn-ghost:hover{border-color:var(--c-primary);color:var(--c-primary);transform:translateY(-2px)}
.btn-soft{background:var(--c-primary-soft);color:var(--c-primary)}
.btn-soft:hover{filter:brightness(1.05);transform:translateY(-2px)}
.btn-block{width:100%}
.btn-lg{padding:15px 32px;font-size:16px}
.btn-sm{padding:9px 16px;font-size:13.5px;border-radius:10px}

/* 毒液：按钮"流体"扫光 */
[data-theme="venom"] .btn-primary::before{
  content:"";position:absolute;top:0;left:-70%;width:55%;height:100%;
  background:linear-gradient(100deg,transparent,rgba(255,255,255,.28),transparent);
  transform:skewX(-22deg);transition:left .55s ease;
}
[data-theme="venom"] .btn-primary:hover::before{left:120%}

/* ---------- 输入 ---------- */
.field{margin-bottom:16px;text-align:left}
.field label{display:block;font-size:13.5px;font-weight:600;margin-bottom:7px;color:var(--c-text-2)}
.input{
  width:100%;padding:13px 15px;border-radius:var(--radius-sm);
  background:var(--c-surface);border:1.5px solid var(--c-border);
  color:var(--c-text);outline:none;
  transition:border-color .22s,box-shadow .22s,background .22s;
}
.input::placeholder{color:var(--c-text-3)}
.input:focus{
  border-color:var(--c-primary);
  box-shadow:0 0 0 4px var(--ring);
}
.input.is-error{border-color:var(--c-danger);box-shadow:0 0 0 4px rgba(239,68,68,.18)}
.input.is-ok{border-color:var(--c-success)}

.err{
  display:none;align-items:center;gap:6px;
  margin-top:7px;font-size:12.5px;color:var(--c-danger);font-weight:500;
}
.err.show{display:flex;animation:shakeIn .35s ease}
@keyframes shakeIn{
  0%{opacity:0;transform:translateX(-6px)}
  60%{transform:translateX(3px)}
  100%{opacity:1;transform:translateX(0)}
}

/* ---------- 主题切换按钮 ---------- */
.theme-toggle{
  display:inline-flex;align-items:center;gap:7px;
  padding:8px 14px;border-radius:999px;
  background:var(--c-surface);border:1px solid var(--c-border);
  color:var(--c-text-2);font-size:13px;font-weight:600;
  transition:color .22s,border-color .22s,transform .22s,box-shadow .22s;
}
.theme-toggle:hover{
  color:var(--c-primary);border-color:var(--c-primary);transform:translateY(-1px);
  box-shadow:0 6px 18px color-mix(in srgb,var(--c-primary) 24%,transparent);
}
.theme-toggle .ic{width:14px;height:14px;border-radius:50%;background:var(--grad);flex:none}

/* ---------- 顶部导航 ---------- */
.navbar{
  position:sticky;top:0;z-index:100;
  background:color-mix(in srgb,var(--c-bg) 82%,transparent);
  backdrop-filter:blur(18px);-webkit-backdrop-filter:blur(18px);
  border-bottom:1px solid var(--c-border);
  transition:box-shadow .3s;
}
.navbar.scrolled{box-shadow:0 6px 26px rgba(16,24,40,.06)}
.navbar .inner{display:flex;align-items:center;gap:28px;height:66px}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;font-size:19px;letter-spacing:-.3px}
.brand .mark{
  width:34px;height:34px;border-radius:11px;background:var(--grad);
  display:grid;place-items:center;color:#fff;font-size:15px;font-weight:800;
  box-shadow:0 5px 16px color-mix(in srgb,var(--c-primary) 40%,transparent);
}
.brand small{display:block;font-size:10.5px;font-weight:600;color:var(--c-text-3);
  letter-spacing:1.4px;margin-top:-3px}
.nav-links{display:flex;gap:26px;flex:1;font-size:14.5px;color:var(--c-text-2);font-weight:500}
.nav-links a{transition:color .22s;position:relative}
.nav-links a::after{
  content:"";position:absolute;left:0;bottom:-6px;height:2px;width:0;
  background:var(--grad);border-radius:2px;transition:width .26s;
}
.nav-links a:hover{color:var(--c-primary)}
.nav-links a:hover::after{width:100%}

/* ---------- 通用排版 ---------- */
.eyebrow{
  display:inline-block;padding:6px 15px;border-radius:999px;
  background:var(--c-primary-soft);color:var(--c-primary);
  font-size:12.5px;font-weight:700;letter-spacing:.6px;margin-bottom:16px;
}
.section{padding:88px 0}
.section-head{text-align:center;max-width:660px;margin:0 auto 52px}
.section-head h2{
  font-size:38px;font-weight:800;letter-spacing:-.8px;line-height:1.25;
  margin-bottom:14px;
}
.section-head p{font-size:16px;color:var(--c-text-2);line-height:1.75}
.grad-text{
  background:var(--grad);-webkit-background-clip:text;background-clip:text;
  -webkit-text-fill-color:transparent;color:transparent;
}

/* ---------- 出现动画 ---------- */
.reveal{opacity:0;transform:translateY(24px);transition:opacity .6s ease,transform .6s cubic-bezier(.22,1,.36,1)}
.reveal.in{opacity:1;transform:none}

@media(max-width:860px){
  .nav-links{display:none}
  .section{padding:60px 0}
  .section-head h2{font-size:29px}
  .container{padding:0 18px}
}