/* 台灣實用計算機 — 共用樣式（品牌 token + 元件），深/淺色 */
:root{
  --gold1:#FCE38A; --gold2:#F5C542; --gold3:#E0A422;
  --radius:18px; --radius-sm:12px; --ease:cubic-bezier(.16,1,.3,1);
  --teal:#1D9E75;
  color-scheme:dark;
  --ink:#EAEEF6; --muted:#97A0B5; --faint:#7A8298; --body:#cdd3e0; --gold-text:#F5C542;
  --glass:rgba(255,255,255,.055); --glass-strong:rgba(255,255,255,.09);
  --hair:rgba(255,255,255,.10); --hair-soft:rgba(255,255,255,.06); --track:rgba(9,14,26,.55);
  --key:rgba(255,255,255,.07); --key-ink:#EAEEF6;
  --page-bg:
    radial-gradient(120% 90% at 15% -10%, rgba(245,197,66,.16), transparent 55%),
    radial-gradient(110% 80% at 100% 10%, rgba(94,120,210,.14), transparent 50%),
    linear-gradient(160deg,#243049,#0F1626 70%);
}
:root[data-theme="light"]{
  color-scheme:light;
  --ink:#1B2438; --muted:#5A6478; --faint:#8A93A8; --body:#3d4657; --gold-text:#8a5a00;
  --glass:rgba(255,255,255,.66); --glass-strong:rgba(255,255,255,.85);
  --hair:rgba(20,30,55,.13); --hair-soft:rgba(20,30,55,.07); --track:rgba(20,30,55,.055);
  --key:#ffffff; --key-ink:#1B2438;
  --page-bg:
    radial-gradient(120% 90% at 12% -10%, rgba(245,197,66,.24), transparent 54%),
    radial-gradient(120% 90% at 100% 6%, rgba(93,202,165,.20), transparent 52%),
    linear-gradient(160deg,#EEF3FB,#DEE7F4 80%);
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:-apple-system,BlinkMacSystemFont,"PingFang TC","Noto Sans TC","Microsoft JhengHei",sans-serif;
  color:var(--ink);line-height:1.7;min-height:100dvh;background:var(--page-bg);background-attachment:fixed;
  -webkit-font-smoothing:antialiased;transition:color .3s var(--ease)}
.wrap{max-width:1040px;margin:0 auto;padding:0 18px}
a,button,summary,label,select{touch-action:manipulation}
a:focus-visible,button:focus-visible,summary:focus-visible,input:focus-visible,select:focus-visible,[tabindex]:focus-visible{outline:2px solid var(--gold3);outline-offset:2px;border-radius:8px}
.tnum{font-variant-numeric:tabular-nums}
.katex{font-size:1.05em}

/* header */
header.site{padding:18px 0 6px;display:flex;align-items:center;justify-content:space-between;gap:12px}
.brand{display:flex;align-items:center;gap:11px;text-decoration:none;color:var(--ink);width:fit-content}
.brand img{width:34px;height:34px;border-radius:9px}
.brand b{font-weight:600;font-size:17px;letter-spacing:.01em}
.brand span{font-size:12px;color:var(--muted);display:block;margin-top:-2px}
.theme-btn{width:42px;height:42px;flex:none;border-radius:12px;border:1px solid var(--hair);background:var(--glass);backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);color:var(--ink);cursor:pointer;display:flex;align-items:center;justify-content:center;transition:transform .18s var(--ease),background .2s var(--ease)}
.theme-btn:hover{background:var(--glass-strong)}
.theme-btn:active{transform:scale(.92) rotate(-8deg)}
.theme-btn svg{width:20px;height:20px}
.theme-btn .i-moon{display:none}
:root[data-theme="light"] .theme-btn .i-sun{display:none}
:root[data-theme="light"] .theme-btn .i-moon{display:block}

/* 麵包屑 */
.crumb{font-size:12px;color:var(--faint);padding:8px 0 0;display:flex;flex-wrap:wrap;gap:6px;align-items:center}
.crumb a{color:var(--muted);text-decoration:none}
.crumb a:hover{color:var(--gold-text)}
.crumb .sep{opacity:.5}

/* hero */
.hero{padding:16px 0 6px}
.hero h1{font-size:clamp(24px,5.2vw,34px);font-weight:700;letter-spacing:.01em;line-height:1.3}
.hero h1 em{font-style:normal;background:linear-gradient(180deg,var(--gold1),var(--gold3));-webkit-background-clip:text;background-clip:text;color:transparent}
:root[data-theme="light"] .hero h1 em{background:linear-gradient(180deg,#C8860A,#7a4f00);-webkit-background-clip:text;background-clip:text}
.hero p{color:var(--muted);margin-top:10px;font-size:15px;max-width:660px}

/* glass 面板 */
.glass{background:var(--glass);backdrop-filter:blur(18px) saturate(140%);-webkit-backdrop-filter:blur(18px) saturate(140%);border:1px solid var(--hair);border-radius:var(--radius);box-shadow:0 1px 0 rgba(255,255,255,.06) inset,0 20px 40px -24px rgba(0,0,0,.5)}
.panel{padding:18px}
@media(min-width:860px){.panel{padding:22px}}
.panel-title{font-size:13px;color:var(--muted);margin-bottom:12px}

/* 分段控制 */
.seg{position:relative;display:flex;background:var(--track);border:1px solid var(--hair-soft);border-radius:12px;padding:4px}
.seg-thumb{position:absolute;top:4px;bottom:4px;left:4px;border-radius:9px;background:linear-gradient(180deg,var(--gold1),var(--gold2));box-shadow:0 6px 18px -8px rgba(245,197,66,.75);z-index:0;transition:transform .34s var(--ease);will-change:transform}
.seg button{position:relative;z-index:1;flex:1;min-height:44px;border:0;background:transparent;color:var(--muted);font-size:15px;font-family:inherit;font-weight:500;border-radius:9px;cursor:pointer;transition:color .28s var(--ease),transform .1s var(--ease)}
.seg button:hover{color:var(--ink)}
.seg button:active{transform:scale(.97)}
.seg button[aria-pressed="true"]{color:#3a2c05;font-weight:600}

/* 輸入 */
.field-label{font-size:13px;color:var(--muted);margin:14px 0 7px}
.vgrid{display:grid;grid-template-columns:repeat(auto-fit,minmax(120px,1fr));gap:10px}
.vgrid label{font-size:12px;color:var(--muted);display:block;margin-bottom:5px}
input.num,select.styled{width:100%;min-height:48px;border:1px solid var(--hair);background:var(--glass-strong);color:var(--ink);border-radius:12px;padding:8px 12px;font-size:16px;font-family:inherit;outline:none;font-variant-numeric:tabular-nums}
input.num:focus,select.styled:focus{border-color:var(--gold3)}
.btn-solve{margin-top:14px;width:100%;min-height:52px;border:0;border-radius:14px;background:linear-gradient(180deg,var(--gold1),var(--gold3));color:#3a2c05;font-size:17px;font-weight:700;font-family:inherit;cursor:pointer;transition:transform .1s var(--ease)}
.btn-solve:active{transform:scale(.98)}

/* 逐步解題 SolutionSteps */
.steps{margin-top:14px;background:var(--glass-strong);border:1px solid var(--hair);border-radius:14px;padding:15px 16px}
.steps .lbl{font-size:13px;color:var(--muted);margin-bottom:12px}
.step{display:flex;gap:10px;margin-bottom:13px}
.step .no{width:23px;height:23px;flex:none;border-radius:50%;background:var(--gold2);color:#3a2c05;font-size:12px;font-weight:700;display:flex;align-items:center;justify-content:center}
.step .body .reason{font-size:13px;color:var(--muted);margin-bottom:3px}
.step .body .math{font-size:16px;overflow-x:auto}
.answer-row{border-top:1px solid var(--hair);margin-top:4px;padding-top:12px;display:flex;align-items:baseline;justify-content:space-between;gap:12px;flex-wrap:wrap}
.answer-row .k{font-size:14px;color:var(--muted)}
.answer-row .v{font-size:22px;font-weight:700;color:var(--gold-text);font-variant-numeric:tabular-nums}
.hint{font-size:14px;color:var(--faint);text-align:center;padding:8px}

/* 廣告位 */
.ad-slot{margin:24px 0;min-height:100px;display:flex;align-items:center;justify-content:center;border:1px dashed var(--hair);border-radius:12px;background:var(--glass);color:var(--faint);font-size:11px;letter-spacing:.28em;text-align:center;overflow:hidden}
.ad-slot::before{content:"廣告"}
@media(min-width:860px){.ad-slot{min-height:120px}}

/* 內容 / 觀念 / 範例 / FAQ */
.content{margin:34px 0 20px}
.content h2{font-size:21px;font-weight:600;margin:26px 0 12px}
.content h3{font-size:16px;font-weight:600;margin:18px 0 6px;color:var(--gold-text)}
.content p{color:var(--body);font-size:15px;margin-bottom:12px}
.content ul,.content ol{color:var(--body);font-size:15px;margin:0 0 12px 20px}
.content li{margin-bottom:6px}
.content .policy-date{font-size:13px;color:var(--faint);margin:-4px 0 16px}
.example{background:var(--glass);border:1px solid var(--hair-soft);border-radius:14px;padding:15px 16px;margin:12px 0}
.example .q{font-weight:600;margin-bottom:8px}
.example .math{overflow-x:auto;margin:6px 0}
details.faq{border-bottom:1px solid var(--hair-soft);padding:14px 2px}
details.faq summary{font-size:15px;font-weight:500;cursor:pointer;list-style:none;display:flex;justify-content:space-between;gap:12px}
details.faq summary::-webkit-details-marker{display:none}
details.faq summary::after{content:"+";color:var(--gold-text);font-size:20px;transition:transform .2s var(--ease)}
details.faq[open] summary::after{transform:rotate(45deg)}
details.faq p{margin:10px 0 2px;font-size:14px;color:var(--body)}
.disclaimer{font-size:12px;color:var(--faint);margin-top:16px;line-height:1.6}

/* 頁尾 + 信任頁連結 */
footer.site{border-top:1px solid var(--hair-soft);margin-top:30px;padding:22px 0 42px;color:var(--faint);font-size:13px;text-align:center}
footer.site nav{display:flex;flex-wrap:wrap;gap:14px;justify-content:center;margin-bottom:12px}
footer.site a{color:var(--muted);text-decoration:none}
footer.site a:hover{color:var(--gold-text)}
footer.site .foot-note{max-width:620px;margin:0 auto 6px;line-height:1.6}
footer.site .foot-copy{margin:0;opacity:.75}

@media(prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}

/* ===== 台灣工具箱 portal ===== */
.portal-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:16px;margin:8px 0}
.pcard{display:flex;flex-direction:column;text-decoration:none;color:var(--ink);padding:22px;border-radius:var(--radius);position:relative;transition:transform .2s var(--ease),border-color .2s var(--ease)}
a.pcard:hover{transform:translateY(-3px);border-color:var(--gold2)}
.pcard .top{display:flex;align-items:center;gap:12px;margin-bottom:11px}
.pcard .ic{width:46px;height:46px;flex:none;border-radius:12px;background:linear-gradient(180deg,var(--gold1),var(--gold3));display:flex;align-items:center;justify-content:center;color:#3a2c05}
.pcard .ic svg{width:25px;height:25px}
.pcard h3{font-size:18px;font-weight:600;letter-spacing:.01em}
.pcard .host{font-size:12px;color:var(--muted);margin-top:1px;font-variant-numeric:tabular-nums}
.pcard p{font-size:14px;color:var(--body);line-height:1.7;flex:1}
.pcard .go{margin-top:13px;color:var(--gold-text);font-size:14px;font-weight:600}
.badge{display:inline-block;font-size:11px;font-weight:600;letter-spacing:.03em;padding:2px 9px;border-radius:99px;margin-left:auto;flex:none}
.badge.live{color:#0a8a34;background:rgba(16,170,70,.16)}
.badge.soon{color:var(--faint);background:var(--glass-strong)}
:root[data-theme="light"] .badge.live{color:#0a7a2e}
.feature-list{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:12px;margin:14px 0}
.feature-list .f{background:var(--glass);border:1px solid var(--hair-soft);border-radius:var(--radius-sm);padding:14px 16px}
.feature-list .f b{color:var(--ink);font-size:15px}
.feature-list .f span{display:block;font-size:13px;color:var(--muted);margin-top:4px;line-height:1.6}