:root{color-scheme:dark;--bg:#0c1016;--surface:#141b25;--surface2:#192330;--line:#273243;--ink:#f4f7fb;--muted:#a3afbf;--accent:#a8c9fa;--accent2:#83b3f2;--green:#96d5bd;--radius:18px;--shadow:0 20px 60px rgba(0,0,0,.23)}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--ink);font-family:'DM Sans','Noto Sans JP',system-ui,sans-serif;font-size:15px;line-height:1.7}button,input,select{font:inherit}button{cursor:pointer}a{color:inherit;text-decoration:none}a:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible{outline:2px solid var(--accent);outline-offset:3px}.layout{max-width:1120px;margin:0 auto;padding:0 28px}.topbar{border-bottom:1px solid var(--line);position:sticky;top:0;background:rgba(12,16,22,.94);backdrop-filter:blur(16px);z-index:20}.topbar-inner{height:78px;display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{display:inline-flex;align-items:center;gap:12px;font-weight:700;letter-spacing:.18em;font-size:19px}.mark{width:40px;height:40px;flex:none}.mark .top{fill:#eef3fa}.mark .stem{fill:#eef3fa}.mark .chip{fill:var(--accent)}.nav{display:flex;gap:28px;align-items:center;color:var(--muted);font-size:13px}.nav a:hover{color:#fff}.nav a.active{color:#fff}.tag{color:var(--accent);font-weight:700;letter-spacing:.22em;font-size:11px}.hero{padding:98px 0 74px;max-width:810px}.hero h1{font-size:clamp(36px,5.2vw,64px);font-weight:600;line-height:1.34;letter-spacing:-.055em;margin:18px 0 22px}.hero p{font-size:17px;color:var(--muted);max-width:650px;margin:0}.hero-cta{margin-top:32px;display:flex;gap:12px;flex-wrap:wrap}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border-radius:11px;border:1px solid var(--line);background:var(--surface2);padding:11px 18px;color:#eff5ff;font-size:13px;font-weight:700;transition:.2s}.btn:hover{transform:translateY(-1px);border-color:#58759a}.btn.primary{background:#d3e4ff;color:#142033;border-color:#d3e4ff}.btn.primary:hover{background:#fff}.btn:disabled{opacity:.45;cursor:not-allowed}.section{padding:24px 0 80px}.section-title{display:flex;align-items:flex-end;justify-content:space-between;gap:18px;margin-bottom:24px}.section-title h2{font-size:27px;letter-spacing:-.03em;margin:4px 0 0}.subtle{color:var(--muted)}.small{font-size:12px}.eyebrow{font-size:11px;letter-spacing:.2em;color:var(--accent);font-weight:700}.searchbar{display:flex;align-items:center;gap:12px;background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:0 18px;margin-bottom:18px;max-width:100%}.searchbar input{width:100%;padding:17px 0;background:transparent;border:0;outline:none;color:var(--ink)}.searchbar input::placeholder{color:#7d8da4}.filterbar{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:24px}.chipbtn{background:transparent;border:1px solid var(--line);color:var(--muted);border-radius:999px;padding:8px 14px;font-size:12px}.chipbtn[aria-pressed=true]{background:#293b53;color:#e8f2ff;border-color:#3e5473}.tool-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}.tool-card{border:1px solid var(--line);border-radius:17px;background:var(--surface);padding:26px;min-height:210px;display:flex;flex-direction:column;gap:20px;transition:.2s}.tool-card:hover{border-color:#516581;background:#19222f;transform:translateY(-2px)}.card-head{display:flex;align-items:flex-start;justify-content:space-between;gap:10px}.glyph{width:45px;height:45px;border-radius:12px;background:#263649;color:var(--accent);display:flex;align-items:center;justify-content:center;font-size:20px;font-weight:700}.card-label{color:#87a4c5;border-radius:20px;background:#202c3b;font-size:10px;padding:3px 10px;letter-spacing:.05em}.tool-card h3{font-size:19px;letter-spacing:-.015em;margin:0 0 6px}.tool-card p{margin:0;color:var(--muted);font-size:13px}.card-bottom{margin-top:auto;font-size:12px;color:var(--accent)}.info-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.info{border-top:1px solid var(--line);padding-top:18px}.info strong{font-size:14px}.info p{color:var(--muted);font-size:13px;margin:8px 0}.site-footer{padding:40px 0;border-top:1px solid var(--line);margin-top:40px;display:flex;justify-content:space-between;gap:18px;align-items:center;flex-wrap:wrap}.foot-brand{letter-spacing:.18em;font-size:16px;font-weight:700}.foot-note{font-size:12px;color:var(--muted)}.detail-intro{padding:72px 0 36px}.breadcrumbs{color:var(--muted);font-size:12px;margin-bottom:20px}.breadcrumbs a:hover{color:#fff}.detail-intro h1{font-size:clamp(29px,4vw,46px);letter-spacing:-.04em;margin:10px 0}.detail-intro p{color:var(--muted);max-width:750px;margin:0}.calculator{border-radius:20px;border:1px solid var(--line);background:var(--surface);padding:30px;margin-bottom:36px}.form-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}.field{display:flex;flex-direction:column;gap:8px}.field label{font-weight:600;font-size:13px}.field input,.field select{width:100%;border:1px solid #344254;background:#0e151f;border-radius:10px;color:var(--ink);padding:13px 14px;min-height:50px}.field small{color:var(--muted);font-size:11px}.checklabel{display:flex;align-items:center;gap:10px;font-size:13px;color:var(--muted)}.checklabel input{accent-color:#aac9f7;width:17px;height:17px}.result{border:1px solid #354b62;background:#1b2939;padding:24px;border-radius:14px;margin-top:25px}.result-label{font-size:12px;letter-spacing:.04em;color:#b2c7e1;margin:0 0 4px}.result-number{font-size:clamp(30px,5vw,46px);font-weight:700;letter-spacing:-.04em;line-height:1.3;margin:0;color:#f1f7ff;font-variant-numeric:tabular-nums}.metric-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin-top:20px}.metric{background:#121c28;border-radius:11px;padding:15px}.metric span{display:block;color:var(--muted);font-size:11px}.metric strong{display:block;font-size:18px;margin-top:5px;font-variant-numeric:tabular-nums}.disclaimer{font-size:12px;color:var(--muted);margin:15px 0 0}.explain{max-width:780px;margin-bottom:55px}.explain h2{font-size:22px}.explain p,.explain li{color:var(--muted);font-size:14px}.error{margin-top:12px;color:#ffb4b4;font-size:13px}.sheet-canvas{padding:16px;background:#0e151f;border:1px solid #344254;border-radius:12px;overflow:auto;margin-top:14px}.sheet-illustration{width:100%;height:auto;max-height:330px;display:block}.empty{border:1px dashed var(--line);border-radius:12px;padding:25px;text-align:center;color:var(--muted)}.back-link{color:var(--accent);font-size:13px}.hidden{display:none!important}.mobile-menu{display:none}
@media(max-width:740px){.layout{padding:0 20px}.topbar-inner{height:70px}.nav{gap:12px;font-size:11px}.nav a:nth-child(2){display:none}.brand{font-size:16px}.mark{height:34px;width:34px}.hero{padding:72px 0 50px}.hero p{font-size:15px}.tool-grid,.form-grid,.info-grid{grid-template-columns:1fr}.section{padding-bottom:50px}.tool-card{min-height:180px;padding:21px}.calculator{padding:20px}.metric-grid{grid-template-columns:1fr}.detail-intro{padding-top:48px}.site-footer{margin-top:20px}}

/* v0.2: simpler, more compact interface; calculators and functionality preserved. */
.topbar-inner{height:66px}
.mark{width:34px;height:34px}
.brand{gap:10px;font-size:18px}
.nav{gap:16px}
.hero.compact-hero{padding:57px 0 48px;max-width:none}
.compact-hero .tag{font-size:10px;letter-spacing:.18em}
.compact-hero h1{font-size:clamp(29px,4.2vw,44px);font-weight:600;letter-spacing:-.055em;line-height:1.35;margin:12px 0 10px}
.compact-hero p{font-size:14px;max-width:none}
.tools-section{padding:0 0 56px}
.tools-section .section-title{align-items:center;margin-bottom:16px}
.tools-section .section-title h2{font-size:21px;margin:0;letter-spacing:-.025em}
.tools-section .searchbar{max-width:none;margin:0 0 16px;border-radius:11px;gap:9px;padding:0 15px;color:#9daec4}
.tools-section .searchbar input{padding:12px 0;font-size:14px}
.tools-section .filterbar{margin-bottom:18px;gap:8px}
.tools-section .chipbtn{font-size:12px;padding:7px 13px}
.tools-section .tool-grid{gap:12px}
.tools-section .tool-card{min-height:147px;padding:20px;gap:14px;border-radius:14px}
.tools-section .glyph{width:36px;height:36px;font-size:18px;border-radius:10px}
.tools-section .card-arrow{color:var(--muted);font-size:19px;font-weight:400;line-height:1}
.tools-section .tool-card h3{font-size:17px;margin:0 0 3px}
.tools-section .tool-card p{font-size:12px;line-height:1.65}
.site-footer{margin-top:0;padding:26px 28px}
.detail-intro{padding:46px 0 25px}
.detail-intro h1{font-size:clamp(27px,4vw,38px);margin:9px 0 7px}
.detail-intro p{font-size:14px}
.calculator{padding:24px;margin-bottom:24px}
.explain{margin-bottom:42px}
@media(max-width:740px){
 .layout{padding-left:18px;padding-right:18px}
 .topbar-inner{height:62px}
 .brand{font-size:16px}
 .hero.compact-hero{padding:43px 0 37px}
 .compact-hero h1{font-size:clamp(25px,7vw,33px)}
 .compact-hero p{font-size:13px}
 .tools-section .section-title h2{font-size:19px}
 .tools-section .tool-card{min-height:130px;padding:17px}
 .tools-section .filterbar{gap:6px}
 .tools-section .chipbtn{padding:6px 10px;font-size:11px}
 .site-footer{padding:22px 18px}
 .calculator{padding:18px}
}


/* v0.3: retain v0.2 visual identity, reduce tapping and scrolling on phones. */
.result-actions{display:flex;flex-wrap:wrap;gap:10px;margin-top:17px}
.result-actions .btn{min-height:44px;padding:10px 16px}
.result-actions .reset-btn{background:transparent;color:var(--muted)}
.action-feedback{color:var(--green);min-height:0;margin:0;font-size:12px}
.action-feedback:not(:empty){margin-top:8px}
.result-number{overflow-wrap:anywhere}
.metric strong{overflow-wrap:anywhere}
.field input:invalid{box-shadow:none}
@media(hover:hover){.btn:hover{transform:translateY(-1px)}}
@media(max-width:740px){
  .topbar-inner{height:58px}
  .hero.compact-hero{padding:33px 0 29px}
  .compact-hero h1{font-size:clamp(24px,6.5vw,32px);margin:8px 0}
  .tools-section .section-title{margin-bottom:12px}
  .tools-section .searchbar{margin-bottom:12px}
  .tools-section .searchbar input{font-size:16px;padding:11px 0;min-height:44px}
  .tools-section .filterbar{gap:7px;margin-bottom:15px;flex-wrap:nowrap;overflow-x:auto;overscroll-behavior-inline:contain;padding-bottom:5px;scrollbar-width:thin}
  .tools-section .chipbtn{font-size:12px;white-space:nowrap;flex:none;min-height:42px;padding:7px 13px}
  .tools-section .tool-grid{gap:9px}
  .tools-section .tool-card{min-height:102px;padding:15px;display:grid;grid-template-columns:36px minmax(0,1fr);align-items:center;gap:13px}
  .tools-section .tool-card .card-head{display:contents}
  .tools-section .tool-card .glyph{grid-column:1;grid-row:1}
  .tools-section .tool-card .card-arrow{grid-column:2;grid-row:1;justify-self:end;align-self:start}
  .tools-section .tool-card>div:last-child{grid-column:2;grid-row:1;padding-right:25px}
  .tools-section .tool-card h3{font-size:15px}
  .tools-section .tool-card p{font-size:11px;line-height:1.5}
  .detail-intro{padding:27px 0 22px}
  .detail-intro h1{font-size:27px}
  .calculator{display:flex;flex-direction:column;padding:14px;border-radius:15px}
  .calculator>.result{order:-1;margin:0 0 17px;padding:17px}
  .calculator>.result .result-number{font-size:clamp(26px,8vw,36px)}
  .calculator>.form-grid{order:0;gap:14px}
  .calculator>div:has(.checklabel){order:0}
  .calculator>.error{order:2}
  .metric-grid{gap:8px;margin-top:14px}
  .metric{padding:11px 13px}
  .metric strong{font-size:16px}
  .field{gap:5px}
  .field input,.field select{font-size:16px;min-height:52px}
  .result-actions .btn{flex:1;min-width:0;font-size:12px}
  .explain{margin-bottom:30px}
}
@media(max-width:370px){.result-actions{flex-direction:column}.tool-card h3{font-size:14px}}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important;transition:none!important;animation:none!important}}

/* v1.0: tidy utility directory and new tools. */
.skip-link{position:absolute;left:12px;top:-100px;z-index:50;padding:10px 14px;background:#d3e4ff;color:#111b29;border-radius:8px}.skip-link:focus{top:10px}
.tool-card:focus-visible{outline:2px solid var(--accent);outline-offset:3px}.tool-card:active{transform:scale(.995)}
.field textarea{width:100%;background:#0e151f;color:var(--ink);border:1px solid #344254;border-radius:10px;padding:13px 14px;resize:vertical;min-height:185px;line-height:1.65;font-size:16px}.field textarea:focus-visible{outline:2px solid var(--accent);outline-offset:3px}
.field select{appearance:auto}.metric-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
.about-copy{min-height:45vh;max-width:790px}.about-copy h2:not(:first-child){margin-top:30px}.about-copy p{line-height:1.95}
.site-footer a:hover{text-decoration:underline;color:#fff}.site-footer a:focus-visible{outline:2px solid var(--accent);outline-offset:3px}
.tools-section .tool-card{min-height:142px}.calculator .result{scroll-margin-top:80px}
@media(min-width:1020px){.tools-section .tool-grid{grid-template-columns:repeat(3,minmax(0,1fr))}}
@media(max-width:740px){.field textarea{min-height:150px}.metric-grid{grid-template-columns:1fr}.tools-section .tool-card{min-height:103px}}

/* v1.2: extra guidance follows the calculator and preserves the original compact layout */
.seo-guide {margin-top:16px; padding-top:20px}
.seo-guide h2 {margin:26px 0 8px; font-size:17px; letter-spacing:-.02em}
.seo-guide h2:first-child {margin-top:0}
.seo-guide h3 {margin:0 0 3px; font-size:14px; font-weight:650; color:var(--ink)}
.seo-guide p {color:var(--muted); margin:0 0 12px; font-size:13px; line-height:1.85}
.faq-item {padding:12px 0; border-bottom:1px solid var(--line)}
.related-links {display:flex; flex-wrap:wrap; gap:9px; margin:8px 0 0}
.related-links a {border:1px solid var(--line); background:var(--surface); border-radius:10px; padding:8px 12px; font-size:13px; color:var(--accent)}
.related-links a:hover {border-color:var(--accent2)}
.home-guide {margin:32px 0 4px; padding:16px 0 0; border-top:1px solid var(--line)}
.home-guide h2 {font-size:15px; margin:0 0 5px; font-weight:650}
.home-guide p {font-size:13px; margin:0; color:var(--muted)}
@media(max-width:560px){.seo-guide {margin-top:10px}.related-links a {flex:1 1 auto;text-align:center}}

/* v1.3: browser-only image, PDF and QR tools */
.field.full{grid-column:1/-1}.field input[type=file]{padding:10px;background:#0e151f;color:var(--muted);line-height:1.5}
.field input[type=range]{padding:0;border:0;min-height:32px;accent-color:var(--accent);background:transparent}
.action-strip{display:flex;gap:10px;flex-wrap:wrap;margin-top:22px;align-items:center}
.action-strip .btn{min-height:44px}.btn.soft{background:transparent;color:var(--muted)}
.preview-image{width:100%;max-height:280px;object-fit:contain;background:#101a27;margin-top:16px;border:1px solid #39516a;border-radius:10px}
.qr-result{text-align:center}.qr-frame{display:inline-flex;align-items:center;justify-content:center;padding:12px;background:white;border-radius:12px;margin-top:14px}
.qr-canvas{width:min(270px,65vw);height:auto;display:block;image-rendering:pixelated}
.result-number.smaller{font-size:23px}.file-list{display:flex;flex-direction:column;gap:8px;margin-top:12px}
.file-row{display:flex;justify-content:space-between;align-items:center;gap:12px;word-break:break-all;padding:10px 12px;border:1px solid #33465e;border-radius:10px;background:#121c28;font-size:13px}
.file-row .btn{padding:5px 10px;white-space:nowrap}
@media(max-width:740px){.action-strip .btn{flex:1 1 auto}.qr-canvas{width:min(250px,70vw)}.field.full{grid-column:auto}}

/* v1.4: contact form and modest batch converter styling. */
.contact-note{font-size:13px;color:var(--muted);margin:0 0 18px}.setup-notice{font-size:13px;border:1px solid #5b5c43;color:#f3d79d;background:#2c281b;border-radius:10px;padding:12px 14px;margin:0 0 18px}
.field textarea{width:100%;min-height:150px;border:1px solid #344254;background:#0e151f;color:var(--ink);border-radius:10px;padding:13px 14px;font:inherit;resize:vertical}
.consent-label{display:flex;align-items:flex-start;gap:12px;color:var(--muted);font-size:13px;line-height:1.75;margin-top:24px}
.consent-label input{accent-color:var(--accent);min-width:18px;width:18px;height:18px;margin-top:3px}.text-link{color:var(--accent);text-decoration:underline;text-underline-offset:2px}
.contact-status{margin:14px 0 0;color:var(--muted);font-size:13px}.contact-status.success{color:var(--green)}.contact-status.failure{color:#ffb4b4}
@media(max-width:740px){.nav a:nth-child(2){display:none}.nav a:last-child{display:inline}}

/* v1.5: unobtrusive drag/drop and accessible keyboard focus */
.file-drop{display:flex;align-items:center;gap:13px;padding:13px 15px;margin-top:10px;background:#111c29;border:1px dashed #435773;border-radius:12px;color:#d8e6f7;cursor:pointer;min-height:68px;transition:background .15s,border-color .15s}
.file-drop:hover,.file-drop.drag-over{background:#1d3047;border-color:#96bbf5}
.file-drop:focus-visible{outline:3px solid var(--accent);outline-offset:3px}
.file-drop.is-error{border-color:#e9959b}
.drop-icon{display:grid;place-items:center;border-radius:9px;width:35px;height:35px;flex:none;background:#2b4057;font-size:23px;font-weight:300;color:#bad7ff}
.drop-copy{display:flex;flex-direction:column;font-size:13px;font-weight:600;gap:4px}
.drop-copy small{color:var(--muted);font-weight:400;line-height:1.45}
.trap-field{position:absolute!important;width:1px!important;height:1px!important;overflow:hidden!important;clip-path:inset(50%)!important;white-space:nowrap!important}
@media(max-width:740px){.file-drop{min-height:58px;padding:10px 12px}.drop-copy{font-size:12px}}

/* v1.6 - personal repeat usage & sharing. Hidden until there is history. */
.tool-share{display:flex;align-items:center;gap:11px;flex-wrap:wrap;margin:14px 0 0}
.share-tool-btn,.recent-clear{background:transparent;border:1px solid #3c4b60;color:#b7c9e3;border-radius:9px;padding:8px 12px;cursor:pointer;font:inherit;font-size:12px}
.share-tool-btn:hover,.recent-clear:hover{border-color:#9cbcf1;color:#fff}
.share-tool-btn:focus-visible,.recent-clear:focus-visible,.recent-link:focus-visible{outline:2px solid #a6c8ff;outline-offset:3px}
.share-feedback{color:#a6c8ff;font-size:12px}
.recent-tools{margin:15px 0 19px;padding:13px 15px;border:1px solid var(--line);border-radius:12px;background:#111923}
.recent-head{display:flex;align-items:center;justify-content:space-between;margin-bottom:9px}
.recent-head h2{font-size:13px;margin:0;font-weight:650}
.recent-clear{padding:4px 9px;font-size:11px}
.recent-items{display:flex;flex-wrap:wrap;gap:8px}
.recent-link{border-radius:8px;background:#223147;color:#d3e6ff;font-size:12px;padding:8px 11px;text-decoration:none}
.recent-link:hover{background:#304969}
.practical-tip{margin-top:18px;padding:13px 14px;border:1px solid #344458;border-radius:10px;background:#101a26}
.practical-tip summary{font-size:13px;font-weight:650;color:#d8e6f9;cursor:pointer}
.practical-tip p{font-size:12px;margin:10px 0 0;line-height:1.85}
@media(max-width:740px){.recent-tools{margin:12px 0 16px;padding:12px}.tool-share{margin-top:12px}}