/* ─── 微博超话签到 - Landing Page ─── */
*,*::before,*::after{box-sizing:border-box;margin:0}
img,picture,video,canvas,svg{display:block;max-width:100%}
input,button,textarea,select{font:inherit}

:root{
  --primary:#4f46e5;--primary-light:#6366f1;--accent:#06b6d4;
  --text:#0f172a;--text-2:#334155;--text-3:#64748b;--text-4:#94a3b8;
  --bg:#f0f4f8;--card-bg:rgba(255,255,255,0.65);
  --glass:rgba(255,255,255,0.45);--glass-border:rgba(255,255,255,0.25);
  --radius:14px;--radius-lg:20px;
  --blur:20px;
}

body{
  font-family:-apple-system,"SF Pro Display","PingFang SC","Helvetica Neue","Noto Sans SC",sans-serif;
  background:var(--bg);color:var(--text);line-height:1.6;
  min-height:100vh;overflow-x:hidden;-webkit-font-smoothing:antialiased;
  font-size:.9rem;position:relative;
}
html{scroll-behavior:smooth;}

/* Background */
.bg-layer{
  position:fixed;inset:0;z-index:-2;
  background:
    radial-gradient(ellipse 90vw 70vh at 10% -10%,rgba(79,70,229,0.06),transparent 55%),
    radial-gradient(ellipse 70vw 50vh at 90% 20%,rgba(6,182,212,0.04),transparent 55%),
    radial-gradient(ellipse 60vw 60vh at 40% 90%,rgba(244,114,182,0.04),transparent 55%);
}

/* ─── Nav ─── */
.nav{
  position:fixed;top:0;left:0;right:0;z-index:100;
  display:flex;align-items:center;justify-content:space-between;
  padding:14px 28px;
  background:rgba(255,255,255,0.55);backdrop-filter:blur(var(--blur));
  -webkit-backdrop-filter:blur(var(--blur));
  border-bottom:1px solid rgba(255,255,255,0.3);
}
.nav-brand{font-size:1rem;font-weight:700;color:var(--primary);}
.nav-actions{display:flex;gap:8px;}

/* ─── Buttons ─── */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:6px;
  padding:9px 20px;border-radius:999px;border:none;
  font-size:.85rem;font-weight:600;cursor:pointer;line-height:1.4;
  transition:transform .15s,opacity .15s,background .2s;
  white-space:nowrap;text-decoration:none;
}
.btn:active{transform:scale(.96);}
.btn-primary{
  background:linear-gradient(135deg,var(--primary),var(--primary-light));
  color:#fff;box-shadow:0 4px 14px rgba(79,70,229,.25);
}
.btn-primary:hover{background:linear-gradient(135deg,var(--primary-light),var(--primary));}
.btn-ghost{
  background:var(--glass);color:var(--text);
  border:1px solid var(--glass-border);
}
.btn-ghost:hover{background:rgba(255,255,255,0.7);}
.btn-lg{padding:13px 32px;font-size:1rem;}
.btn-full{width:100%;padding:12px;font-size:.9rem;}

/* ─── Hero ─── */
.hero{
  position:relative;text-align:center;
  padding:140px 20px 80px;overflow:hidden;
}
.hero-glow{
  position:absolute;top:-30%;left:50%;transform:translateX(-50%);
  width:600px;height:600px;
  background:radial-gradient(circle,rgba(79,70,229,0.15),transparent 65%);
  pointer-events:none;
}
.hero-title{
  font-size:3rem;font-weight:900;letter-spacing:-1px;
  background:linear-gradient(135deg,var(--primary),var(--accent),#f472b6);
  -webkit-background-clip:text;-webkit-text-fill-color:transparent;
  background-clip:text;margin-bottom:12px;
  position:relative;
}
.hero-subtitle{
  font-size:1.1rem;color:var(--text-3);max-width:500px;margin:0 auto 32px;
}
.hero-cta{display:flex;gap:12px;justify-content:center;flex-wrap:wrap;}
.hero-stats{display:flex;gap:40px;justify-content:center;margin-top:48px;flex-wrap:wrap;}
.hero-stat{text-align:center;}
.hero-stat .num{display:block;font-size:1.8rem;font-weight:800;color:var(--primary);}
.hero-stat .lbl{font-size:.8rem;color:var(--text-4);margin-top:2px;}

/* ─── Sections ─── */
.section{padding:80px 20px;max-width:1080px;margin:0 auto;}
.section-alt{background:rgba(255,255,255,0.3);border-radius:var(--radius-lg);
  max-width:1120px;margin:0 auto 40px;}
.section-title{text-align:center;font-size:1.75rem;font-weight:800;margin-bottom:8px;}
.section-desc{text-align:center;color:var(--text-3);margin-bottom:48px;font-size:.9rem;}

/* ─── Feature Cards ─── */
.features-grid{
  display:grid;grid-template-columns:repeat(3,1fr);gap:20px;
}
.feature-card{
  background:var(--glass);backdrop-filter:blur(12px);
  -webkit-backdrop-filter:blur(12px);
  border:1px solid var(--glass-border);
  border-radius:var(--radius);padding:28px 22px;
  transition:transform .2s,box-shadow .2s;
}
.feature-card:hover{transform:translateY(-4px);box-shadow:0 8px 30px rgba(15,23,42,.08);}
.feature-icon{font-size:2.2rem;margin-bottom:12px;}
.feature-card h3{font-size:1rem;margin-bottom:6px;}
.feature-card p{font-size:.82rem;color:var(--text-3);line-height:1.6;}

/* ─── Steps Horizontal ─── */
.steps-h{display:flex;align-items:flex-start;justify-content:center;gap:16px;flex-wrap:wrap;}
.step-item{text-align:center;max-width:220px;}
.step-num{
  width:48px;height:48px;border-radius:50%;
  background:linear-gradient(135deg,var(--primary),var(--primary-light));
  color:#fff;font-size:1.3rem;font-weight:800;
  display:flex;align-items:center;justify-content:center;
  margin:0 auto 12px;
}
.step-item h3{font-size:.95rem;margin-bottom:4px;}
.step-item p{font-size:.8rem;color:var(--text-3);}
.step-arrow{font-size:1.5rem;color:var(--text-4);padding-top:12px;}

/* ─── Tutorial Steps ─── */
.tutorial-steps{max-width:700px;margin:0 auto;}
.t-step{
  display:flex;gap:16px;align-items:flex-start;
  padding:18px 0;border-bottom:1px solid rgba(148,163,184,.1);
}
.t-step:last-child{border-bottom:none;}
.t-num{
  font-size:.85rem;font-weight:800;color:var(--primary);
  background:rgba(79,70,229,.08);padding:4px 10px;border-radius:8px;
  white-space:nowrap;flex-shrink:0;
}
.t-step h4{font-size:.9rem;margin-bottom:2px;}
.t-step p{font-size:.8rem;color:var(--text-3);}
.tip-box{
  margin-top:8px;padding:10px 14px;background:rgba(251,191,36,.1);
  border-radius:8px;font-size:.78rem;color:#92400e;
}

/* ─── FAQ ─── */
.faq-list{max-width:700px;margin:0 auto;}
.faq-list details{
  background:var(--glass);backdrop-filter:blur(10px);
  -webkit-backdrop-filter:blur(10px);
  border:1px solid var(--glass-border);
  border-radius:var(--radius);
  padding:16px 20px;margin-bottom:8px;
  transition:background .2s;
}
.faq-list details[open]{background:rgba(255,255,255,0.75);}
.faq-list summary{
  font-weight:600;font-size:.9rem;cursor:pointer;
  list-style:none;display:flex;justify-content:space-between;align-items:center;
}
.faq-list summary::-webkit-details-marker{display:none;}
.faq-list summary::after{content:'+';font-size:1.2rem;color:var(--primary);font-weight:400;}
.faq-list details[open] summary::after{content:'−';}
.faq-list p{padding-top:10px;font-size:.82rem;color:var(--text-3);line-height:1.7;}

/* ─── Footer ─── */
.footer{text-align:center;padding:48px 20px;color:var(--text-4);}
.footer p{font-size:.85rem;}
.footer-sub{font-size:.75rem;margin-top:4px;opacity:.7;}

/* ─── Modal ─── */
.modal-overlay{
  position:fixed;inset:0;z-index:200;
  background:rgba(15,23,42,.3);backdrop-filter:blur(6px);
  -webkit-backdrop-filter:blur(6px);
  display:flex;align-items:center;justify-content:center;
  opacity:0;pointer-events:none;transition:opacity .25s;
}
.modal-overlay.active{opacity:1;pointer-events:auto;}
.modal{
  background:rgba(255,255,255,0.85);backdrop-filter:blur(24px);
  -webkit-backdrop-filter:blur(24px);
  border:1px solid rgba(255,255,255,0.5);
  border-radius:var(--radius-lg);
  padding:36px 32px;width:90%;max-width:420px;
  box-shadow:0 20px 60px rgba(15,23,42,.12);
  position:relative;transform:translateY(20px);
  transition:transform .25s;
}
.modal-overlay.active .modal{transform:translateY(0);}
.modal-close{
  position:absolute;top:12px;right:14px;
  background:none;border:none;font-size:1.3rem;
  color:var(--text-4);cursor:pointer;padding:4px 8px;
  border-radius:8px;transition:background .15s;
}
.modal-close:hover{background:rgba(148,163,184,.1);}
.modal h2{font-size:1.3rem;font-weight:800;margin-bottom:4px;}
.modal-sub{font-size:.82rem;color:var(--text-3);margin-bottom:24px;}

/* ─── Form ─── */
.form-group{margin-bottom:16px;}
.form-group label{display:block;font-size:.8rem;font-weight:600;margin-bottom:5px;color:var(--text-2);}
.form-group input{
  width:100%;padding:10px 14px;border:1px solid rgba(148,163,184,.2);
  border-radius:10px;font-size:.88rem;background:rgba(255,255,255,.5);
  transition:border-color .2s,box-shadow .2s;
}
.form-group input:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(79,70,229,.1);}
.form-error{color:#ef4444;font-size:.78rem;min-height:20px;margin-bottom:8px;}
.modal-switch{text-align:center;margin-top:16px;font-size:.82rem;color:var(--text-3);}
.modal-switch a{color:var(--primary);font-weight:600;text-decoration:none;}
.modal-switch a:hover{text-decoration:underline;}

/* ─── Toast ─── */
#toast{
  position:fixed;bottom:28px;left:50%;transform:translateX(-50%) translateY(100px);
  background:rgba(30,30,50,.9);color:#fff;padding:10px 22px;
  border-radius:999px;font-size:.82rem;font-weight:500;
  z-index:300;opacity:0;
  transition:opacity .3s,transform .3s cubic-bezier(.4,0,.2,1);
  pointer-events:none;
}
#toast.show{opacity:1;transform:translateX(-50%) translateY(0);}

/* ─── Responsive ─── */
@media(max-width:768px){
  .nav{padding:12px 16px;}
  .nav-brand{font-size:.9rem;}
  .hero{padding:120px 16px 60px;}
  .hero-title{font-size:2rem;}
  .hero-subtitle{font-size:.9rem;}
  .hero-stats{gap:24px;}
  .hero-stat .num{font-size:1.4rem;}
  .section{padding:60px 16px;}
  .section-title{font-size:1.4rem;}
  .features-grid{grid-template-columns:repeat(2,1fr);gap:14px;}
  .feature-card{padding:20px 16px;}
  .modal{padding:28px 22px;}
}

@media(max-width:540px){
  .nav{padding:10px 14px;}
  .nav-actions .btn{padding:6px 14px;font-size:.8rem;}
  .hero{padding:100px 14px 50px;}
  .hero-title{font-size:1.6rem;}
  .features-grid{grid-template-columns:1fr;}
  .hero-cta{flex-direction:column;align-items:center;}
  .steps-h{flex-direction:column;align-items:center;}
  .step-arrow{transform:rotate(90deg);}
}