:root{
  --ink:#1a1a1a; --fg-muted:#6b7280; --border:#e5e7eb; --bg:#fff; --bg-soft:#f9fafb;
  --primary:#2563eb; --primary-dark:#1d4ed8; --ok:#16a34a; --err:#dc2626;
}
*{box-sizing:border-box}
body{margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;color:var(--ink);background:var(--bg);line-height:1.5}
.wrap{max-width:720px;margin:0 auto;padding:0 20px}
a{color:var(--primary);text-decoration:none}

.site-header{border-bottom:1px solid var(--border);padding:16px 0}
.site-header .wrap{display:flex;justify-content:space-between;align-items:center;gap:14px;flex-wrap:wrap}
.logo{font-weight:700;font-size:1.1rem;color:var(--ink);text-decoration:none}
.site-header nav{display:flex;gap:18px;font-size:.9rem}
.site-header nav a{color:var(--fg-muted)}
.site-header nav a:hover,.site-header nav a.nav-active{color:var(--primary)}

.lang-switcher select{border:1px solid var(--border);background:var(--bg-soft);color:var(--ink);padding:6px 10px;border-radius:7px;font-size:.85rem;font-family:inherit;cursor:pointer}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}

.hero{text-align:center;padding:56px 0 32px}
.hero h1{font-size:2rem;margin:0 0 8px}
.subtitle{color:var(--fg-muted);margin:0}

.converter{padding-bottom:64px}

.format-select{display:flex;gap:8px;justify-content:center;margin-bottom:20px}
.format-option{border:1px solid var(--border);border-radius:8px;padding:10px 18px;cursor:pointer;font-size:.9rem;transition:border-color .15s,background .15s}
.format-option input{margin-inline-end:6px}
.format-option:has(input:checked){border-color:var(--primary);background:#eff6ff;color:var(--primary-dark)}

.dropzone{border:2px dashed var(--border);border-radius:12px;padding:48px 24px;text-align:center;cursor:pointer;transition:border-color .15s,background .15s}
.dropzone:hover,.dropzone.dragover{border-color:var(--primary);background:var(--bg-soft)}
.dropzone-title{font-weight:600;margin:0 0 4px}
.dropzone-sub{color:var(--fg-muted);font-size:.9rem;margin:0}

.task-list{list-style:none;padding:0;margin:24px 0 0;display:flex;flex-direction:column;gap:10px}
.task-item{display:flex;align-items:center;gap:12px;border:1px solid var(--border);border-radius:8px;padding:12px 16px}
.task-name{flex:1;font-size:.9rem;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.task-status{font-size:.82rem;color:var(--fg-muted);white-space:nowrap}
.task-status.completed{color:var(--ok)}
.task-status.failed{color:var(--err)}
.task-download{font-size:.85rem;font-weight:600;white-space:nowrap}

.site-footer{border-top:1px solid var(--border);padding:24px 0;margin-top:48px;color:var(--fg-muted);font-size:.85rem;text-align:center}

/* Content pages: about / faq / contact */
.content-hero{padding:24px 0 20px;border-bottom:1px solid var(--border);margin-bottom:28px}
.content-hero h1{font-size:1.6rem;margin:0 0 8px}
.content-hero .lede{color:var(--fg-muted);margin:0;max-width:60ch}
.content-section{margin-bottom:36px}
.content-section h2{font-size:1.15rem;margin:0 0 12px}
.content-section p{color:var(--fg-muted);margin:0 0 12px}
.content-section p:last-child{margin-bottom:0}
.content-section b{color:var(--ink)}
.content-section code{background:var(--bg-soft);padding:.15em .4em;border-radius:4px;font-size:.9em}

.faq-list{display:flex;flex-direction:column;gap:14px}
.faq-item{background:var(--bg);border:1px solid var(--border);border-radius:10px;padding:16px 18px}
.faq-question{font-weight:600;margin-bottom:6px}
.faq-answer{color:var(--fg-muted);font-size:.92rem;line-height:1.65}
.faq-answer a,.faq-answer code{color:var(--primary)}
.faq-answer code{background:var(--bg-soft);padding:.1em .35em;border-radius:4px;font-size:.92em}

.alert{padding:12px 16px;border-radius:8px;margin-bottom:18px;font-size:.9rem}
.alert-success{background:#ecfdf5;color:var(--ok)}
.alert-error{background:#fef2f2;color:var(--err)}

.contact-form{background:var(--bg-soft);border:1px solid var(--border);border-radius:12px;padding:22px;position:relative}
.form-group{margin-bottom:16px}
.form-label{display:block;margin-bottom:6px;font-weight:600;font-size:.88rem;color:var(--ink)}
.form-input,.form-select{width:100%;border:1px solid var(--border);background:var(--bg);color:var(--ink);padding:10px 12px;border-radius:8px;font-size:.92rem;font-family:inherit}
.form-textarea{resize:vertical}

.btn-sm{border:none;border-radius:7px;padding:6px 12px;font-size:.82rem;cursor:pointer;text-decoration:none;display:inline-block}
.btn-primary{background:var(--primary);color:#fff}