:root{
  --bg:#f5f7fb;
  --card:#ffffff;
  --text:#1f2937;
  --muted:#5f6b7a;
  --line:#dfe5ee;
  --blue:#4b82e7;
  --blue-dark:#3468c9;
  --green-bg:#edf8ec;
  --green-line:#cfe8cc;
  --shadow:0 10px 28px rgba(15,23,42,.06);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  background:var(--bg);
  color:var(--text);
  font-family:Arial,Helvetica,sans-serif;
  line-height:1.65;
}
a{color:#3e72cc;text-decoration:none}
a:hover{text-decoration:underline}
img{max-width:100%;display:block}
.site-wrap{max-width:1120px;margin:0 auto;padding:24px 20px 56px}
.topbar{
  display:flex;justify-content:space-between;align-items:center;gap:16px;
  margin-bottom:24px;
}
.brand a{
  color:#223049;text-decoration:none;font-size:28px;font-weight:700;
}
.topnav{display:flex;gap:18px;flex-wrap:wrap}
.topnav a{color:#445066;font-size:15px}
.hero{text-align:center;margin-bottom:22px}
.kicker{
  display:inline-block;background:#eaf0ff;color:#456fc6;padding:8px 12px;
  border-radius:999px;font-size:13px;font-weight:700;margin-bottom:12px
}
.hero h1{font-size:48px;line-height:1.1;margin:0 0 10px}
.hero p{margin:0 auto;max-width:760px;color:var(--muted);font-size:18px}
.card{
  background:var(--card);border:1px solid var(--line);border-radius:16px;
  box-shadow:var(--shadow)
}
.calc-panel{padding:26px;margin:28px 0 18px}
.calc-grid{display:grid;grid-template-columns:1fr auto 1fr;gap:16px;align-items:end}
.calc-grid.single{grid-template-columns:1fr}
.calc-grid.three{grid-template-columns:1fr 160px 1fr}
.field label{display:block;font-size:14px;font-weight:700;margin:0 0 8px;color:#354154}
.input-wrap{position:relative}
.input-wrap input,.input-wrap select{
  width:100%;height:54px;border:1px solid #cfd7e3;border-radius:10px;
  padding:0 44px 0 16px;font-size:18px;background:#fff;color:#1f2937
}
.input-icon{
  position:absolute;right:14px;top:50%;transform:translateY(-50%);
  color:#8591a3;font-size:18px
}
.mid-dash{font-size:34px;font-weight:700;color:#7c8798;padding-bottom:7px;text-align:center}
.primary-btn{
  width:100%;margin-top:18px;border:none;border-radius:10px;
  background:linear-gradient(180deg,var(--blue),var(--blue-dark));
  color:#fff;height:54px;font-size:22px;font-weight:700;cursor:pointer
}
.result-box{
  margin:18px 0 28px;background:var(--green-bg);border:1px solid var(--green-line);
  border-radius:14px;padding:22px 24px
}
.result-title{font-size:22px;font-weight:700;margin-bottom:10px}
.result-list{margin:0;padding-left:22px}
.result-list li{margin:8px 0;font-size:18px}
.visual-card{padding:26px;margin-bottom:30px}
.calendar-row{display:grid;grid-template-columns:1fr 220px 1fr;gap:20px;align-items:center}
.calendar{border:1px solid var(--line);border-radius:12px;padding:18px;background:#fff}
.calendar h3{text-align:center;margin:0 0 12px;font-size:28px}
.month-grid{display:grid;grid-template-columns:repeat(7,1fr);gap:4px;text-align:center}
.month-grid span{padding:8px 0;border-radius:7px;font-size:15px}
.month-grid .head{color:#6d7888;font-weight:700}
.month-grid .mark-start{background:#4b82e7;color:#fff;font-weight:700}
.month-grid .mark-end{background:#e66b6b;color:#fff;font-weight:700}
.arrow-box{text-align:center;font-weight:700;color:#2c3550}
.arrow-box .days{font-size:42px;margin-bottom:8px}
.arrow{font-size:58px;line-height:1}
.content-grid{display:grid;grid-template-columns:minmax(0,1fr) 320px;gap:28px;align-items:start}
.content-main section{margin-bottom:30px}
.section-card{padding:26px}
.section-card h2{margin:0 0 14px;font-size:34px;line-height:1.15}
.section-card h3{margin:16px 0 10px;font-size:24px}
.section-card p,.section-card li{font-size:18px}
.section-card ul{padding-left:22px}
.examples li{margin:12px 0}
.sidebar .section-card h3{margin:0 0 14px;font-size:26px}
.related-list{margin:0;padding-left:20px}
.related-list li{margin:12px 0}
.faq-item{border-top:1px solid var(--line);padding:16px 0}
.faq-item:first-child{border-top:none}
.faq-q{font-weight:700;font-size:18px;margin-bottom:8px}
.image-caption{color:var(--muted);text-align:center;font-size:15px;margin-top:6px}
.footer{
  margin-top:40px;padding-top:24px;border-top:1px solid var(--line);
  color:#677285;font-size:14px;display:flex;justify-content:space-between;gap:20px;flex-wrap:wrap
}
.footer a{color:#54627a}
.guide-list,.tool-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px}
.mini-card{padding:20px}
.mini-card h3{margin:0 0 10px;font-size:24px}
.mini-card p{margin:0 0 12px;color:var(--muted)}
.notice{
  background:#fff8e6;border:1px solid #f0ddb0;border-radius:12px;padding:14px 16px;
  color:#66511b;font-size:15px;margin-top:18px
}
.breadcrumbs{font-size:14px;color:#6f7a89;margin-bottom:14px}
.breadcrumbs a{color:#5c6b83}
@media (max-width:980px){
  .hero h1{font-size:40px}
  .calendar-row{grid-template-columns:1fr}
  .arrow-box .arrow{transform:rotate(90deg)}
  .content-grid{grid-template-columns:1fr}
}
@media (max-width:720px){
  .calc-grid,.calc-grid.three{grid-template-columns:1fr}
  .mid-dash{display:none}
  .hero h1{font-size:34px}
  .guide-list,.tool-grid{grid-template-columns:1fr}
  .site-wrap{padding:16px 14px 40px}
  .section-card h2{font-size:28px}
}