.envelope-hero{background:linear-gradient(125deg,var(--surface,#eef7f9),var(--bg,#fff));border-bottom:1px solid var(--border,#d7e3e9)}
.envelope-topics{max-width:920px;margin:auto}.envelope-nav{display:flex;flex-wrap:wrap;gap:.6rem;margin:1.5rem 0}.envelope-nav a{padding:.6rem .85rem;border:1px solid var(--border,#ccdce4);border-radius:999px;text-decoration:none}
.envelope-topic{border:1px solid var(--border,#cddce4);border-radius:12px;margin:.8rem 0;background:var(--surface,#fff);scroll-margin-top:7rem}.envelope-topic>summary{padding:1.15rem;cursor:pointer;font-weight:700;line-height:1.55}.envelope-topic[open]>summary{border-bottom:1px solid var(--border,#d7e3e9)}.envelope-topic-body{padding:0 1.2rem 1.2rem}.envelope-topic-body p{max-width:76ch;line-height:1.8}.envelope-group{scroll-margin-top:7rem}.envelope-topic ul{padding-left:1.4rem}
.envelope-calculator{max-width:1050px;margin:auto;scroll-margin-top:7rem}.envelope-calculator form{padding:clamp(1rem,3vw,2rem);border:1px solid var(--border,#cadce3);border-radius:16px;background:var(--surface,#f5f9fb)}.envelope-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:1rem}.envelope-grid label{display:flex;flex-direction:column;gap:.4rem}.envelope-calculator input{width:100%;min-width:0;padding:.7rem;border:1px solid var(--border,#a8becb);border-radius:7px;background:var(--bg,#fff);color:inherit;font:inherit}.envelope-calculator input[aria-invalid]{outline:3px solid #c23737}.envelope-calculator input[type=checkbox]{width:auto;margin-right:.6rem}.envelope-check{display:flex;align-items:flex-start;margin:1rem 0}.envelope-rows{display:grid;gap:.7rem;margin:1rem 0}.envelope-row{display:grid;grid-template-columns:minmax(0,1.3fr) repeat(2,minmax(0,1fr));gap:.6rem;align-items:end;border-bottom:1px solid var(--border,#cbdbe1);padding-bottom:.7rem}.envelope-row label{display:grid;gap:.35rem}.envelope-row>strong{overflow-wrap:anywhere;align-self:center}.envelope-actions{display:flex;flex-wrap:wrap;gap:.7rem;margin:1.3rem 0}.envelope-actions button{min-height:44px;white-space:normal}.envelope-alert{color:var(--text,#263e4e);font-weight:600}.envelope-alert:empty{display:none}.envelope-result{padding:1rem 0;outline-offset:6px}.envelope-total{font-size:clamp(2rem,6vw,3rem);font-weight:800;margin:.3rem 0}.envelope-breakdown{margin:1rem 0}.envelope-breakdown>div{display:grid;grid-template-columns:minmax(0,2fr) minmax(0,1fr);gap:1rem;border-bottom:1px solid var(--border,#d4e1e7);padding:.6rem 0}.envelope-breakdown dd{text-align:right;margin:0}.envelope-result table{width:100%;table-layout:fixed}.envelope-result th,.envelope-result td{overflow-wrap:anywhere}.envelope-calculator .notice{line-height:1.7}.envelope-card{border-left:5px solid var(--accent,#0785a0)}
@media(max-width:600px){.envelope-grid{grid-template-columns:1fr}.envelope-row{grid-template-columns:repeat(2,minmax(0,1fr))}.envelope-row>strong{grid-column:1/-1}.envelope-topic>summary{padding:.9rem}.envelope-topic-body{padding:0 .9rem 1rem}.envelope-nav a{flex:1 1 45%;text-align:center}.envelope-calculator form{padding:.85rem}.envelope-breakdown>div{grid-template-columns:minmax(0,1.8fr) minmax(0,1fr);gap:.5rem}}
@media print{.envelope-topic{display:block}.envelope-topic::details-content{content-visibility:visible}.envelope-calculator button{display:none}}