:root{font-family:Arial,sans-serif;color-scheme:light;color:var(--text);background:var(--page-bg);--page-bg:#fff;--surface:#fff;--field-bg:#fff;--text:#141b28;--blue:#276fe2;--blue-hover:#1b59bf;--quota-blue:#276fe2;--green:#17834b;--green-hover:#126a3c;--success-bg:#edf8f1;--success-ink:#146d3e;--success-line:#b9ddc8;--on-accent:#fff;--muted:#647084;--placeholder:#697589;--line:#e3e9f2;--field-border:#d9e1ed;--focus-border:#5886d1;--focus-ring:#e8f0ff;--theme-track:#f5f7fb;--theme-selected:#e6edfc;--theme-ink:#2458b1;--badge-bg:#edf2fa;--badge-ink:#3764ac;--error:#b63725;--error-bg:#fff0ec}
html[data-theme="dark"]{color-scheme:dark;--page-bg:#11151d;--surface:#1a2130;--field-bg:#1b2435;--text:#edf1f9;--quota-blue:#8ab6ff;--success-bg:#1d332b;--success-ink:#82d8aa;--success-line:#315c45;--muted:#a6b1c4;--placeholder:#9ca8bd;--line:#303c50;--field-border:#364760;--focus-border:#8ab6ff;--focus-ring:#253858;--theme-track:#181f2b;--theme-selected:#293e66;--theme-ink:#d8e7ff;--badge-bg:#26364f;--badge-ink:#aac7ff;--error:#ffb5a8;--error-bg:#412a2a}
*{box-sizing:border-box}
body{margin:0;background:var(--page-bg);color:var(--text)}
button,input{font:inherit}
button{cursor:pointer}
button:disabled{cursor:wait;opacity:.65}
button:focus-visible{outline:3px solid var(--focus-border);outline-offset:4px}
[hidden]{display:none!important}
.page-header{width:100%;min-height:74px;padding:20px 24px 0;display:flex;align-items:flex-start;justify-content:flex-end}
.theme-switch{display:flex;gap:4px;padding:3px;background:var(--theme-track);border:1px solid var(--line);border-radius:8px}
.theme-switch button{display:grid;place-items:center;border:0;background:none;color:var(--muted);min-width:44px;min-height:44px;padding:0;border-radius:5px}
.theme-icon{width:20px;height:20px;fill:none;stroke:currentColor;stroke-width:1.7;stroke-linecap:round;stroke-linejoin:round}
.theme-switch button[aria-pressed="true"]{color:var(--theme-ink);background:var(--theme-selected);font-weight:600}
.theme-switch button:hover:not([aria-pressed="true"]){color:var(--text)}
main{max-width:1080px;margin:0 auto;padding:0 28px 80px}
.downloader{max-width:820px;margin:0 auto;text-align:center;padding:clamp(44px,9svh,86px) 0 0}
h1{margin:0;font-size:36px;line-height:1.3;font-weight:700;letter-spacing:-.9px}
.intro{font-size:15px;line-height:1.8;color:var(--muted);margin:16px 0 36px}
.link-field{display:flex;align-items:center;gap:12px;padding:10px 10px 10px 20px;min-height:70px;border:1px solid var(--field-border);border-radius:8px;background:var(--field-bg)}
.link-field:focus-within{border-color:var(--focus-border);box-shadow:0 0 0 3px var(--focus-ring)}
.link-field input{flex:1;min-width:0;height:48px;border:0;outline:0;color:var(--text);background:none;font-size:17px}
.link-field input::placeholder{color:var(--placeholder);font-size:16px}
.link-field button,.result>button{border:0;border-radius:5px;background:var(--blue);color:var(--on-accent);padding:0 24px;min-height:48px;font-size:15px;font-weight:500;white-space:nowrap}
.link-field button:hover:not(:disabled),.result>button:hover:not(:disabled){background:var(--blue-hover)}
.form-error{font-size:13px;line-height:1.8;color:var(--error);text-align:left;margin:13px 0 0;white-space:pre-line;overflow-wrap:anywhere}
.quota-status{font-size:12px;line-height:1.8;color:var(--muted);text-align:left;margin:10px 2px 0}
.quota-status strong{color:var(--quota-blue);font-size:14px;font-weight:700;margin-right:5px}
#quota-message{color:var(--muted);margin-left:3px}
#quota-retry{border:0;padding:0 6px;min-height:36px;margin-left:3px;background:none;color:var(--quota-blue);font-size:12px;text-decoration:underline;text-underline-offset:3px;vertical-align:middle}
#quota-retry:hover{color:var(--theme-ink)}
.flow-panel{margin-top:16px;padding:16px;border:1px solid var(--line);border-radius:10px;background:var(--surface);text-align:left}
.flow-heading{display:flex;align-items:center;gap:8px;min-height:20px;margin:0 0 12px}
.flow-heading h2{min-width:0;margin:0;font-size:14px;line-height:20px;font-weight:600;overflow-wrap:anywhere}
.flow-panel[data-state="checking"]{display:grid;grid-template-columns:minmax(0,1fr) auto;align-items:center;gap:12px}
.flow-panel[data-state="checking"] .flow-heading{margin:0}
.flow-panel[data-state="checking"] .task-progress{margin:0;padding:0;border:0}
.flow-icon{display:block;flex:none;width:18px;height:18px;fill:none;stroke:currentColor;stroke-width:1.75;stroke-linecap:round;stroke-linejoin:round;color:var(--badge-ink)}
.flow-symbol{display:none}
.flow-symbol-audio{display:inline}
.flow-panel:is([data-state="ready"],[data-state="complete"]){border-color:var(--success-line)}
.flow-panel:is([data-state="ready"],[data-state="complete"]) .flow-heading{color:var(--success-ink)}
.flow-panel:is([data-state="ready"],[data-state="complete"]) .flow-icon{color:var(--success-ink)}
.flow-panel:is([data-state="ready"],[data-state="complete"],[data-state="downloading"],[data-state="error"],[data-state="cancelled"]) .flow-symbol-audio{display:none}
.flow-panel:is([data-state="ready"],[data-state="downloading"]) .flow-symbol-download{display:inline}
.flow-panel[data-state="complete"] .flow-symbol-complete{display:inline}
.flow-panel[data-state="downloading"]{border-color:var(--focus-border)}
.flow-panel[data-state="downloading"] .flow-icon{animation:download-nudge 1.2s ease-in-out infinite}
.flow-panel[data-state="downloading"] #save-button:disabled{opacity:1;cursor:progress}
.flow-panel[data-state="error"]{border-color:var(--error)}
.flow-panel[data-state="error"] .flow-heading{color:var(--error)}
.flow-panel[data-state="error"] .flow-icon{color:var(--error)}
.flow-panel[data-state="error"] .flow-symbol-error{display:inline}
.flow-panel[data-state="cancelled"] .flow-icon{color:var(--muted)}
.flow-panel[data-state="cancelled"] .flow-symbol-cancelled{display:inline}
.status-notice{display:flex;align-items:center;gap:12px;margin-top:10px;padding:11px 13px;border:1px solid var(--field-border);border-radius:8px;background:var(--surface);text-align:left}
.status-notice>div{flex:1;min-width:0}
.status-notice h2{font-size:13px;line-height:1.5;margin:0;color:var(--text)}
.status-notice p{font-size:12px;line-height:1.65;margin:3px 0 0;color:var(--muted);overflow-wrap:anywhere}
.status-notice[data-tone="error"]{border-color:var(--error)}
.status-notice button{flex:none;min-height:44px;padding:0 14px;border:1px solid var(--field-border);border-radius:5px;color:var(--blue);background:var(--field-bg);font-size:13px}
.status-notice button:hover:not(:disabled){border-color:var(--focus-border);background:var(--theme-track)}
#save-notice{margin-top:10px;padding:10px 0 0;border:0;border-top:1px solid var(--line);border-radius:0;background:none}
#save-notice p{margin:0}
#convert-button[data-state="blocked"]{cursor:not-allowed}
@media(max-width:650px){.status-notice{align-items:flex-start;flex-direction:column;gap:10px}.status-notice button{align-self:flex-start}}
.processing{display:flex;align-items:center;gap:9px;margin:8px 0 0;color:var(--muted);font-size:13px;text-align:left}
#processing-text{flex:1;min-width:0;line-height:1.6;overflow-wrap:anywhere}
.spinner{height:14px;width:14px;flex:none;border:2px solid var(--line);border-top-color:var(--focus-border);border-radius:50%;animation:spin .8s linear infinite}
.task-progress{margin-top:14px;padding-top:12px;border-top:1px solid var(--line)}
.progress-caption{display:flex;justify-content:center;gap:12px;text-align:left}
.progress-caption{align-items:center;font-size:12px;line-height:1.6;color:var(--text)}
.progress-caption>span{min-width:0;margin-right:auto;overflow-wrap:anywhere}
.progress-actions{display:flex;align-items:center;gap:12px;flex:none}
.progress-actions strong{font-size:13px;font-variant-numeric:tabular-nums;color:var(--quota-blue)}
.progress-actions .processing{margin:0}
.progress-actions .processing button{margin:0;padding:0 2px;min-height:44px}
#progress-track{display:inline-flex;min-width:0}
.processing button{border:0;padding:4px 10px;min-height:44px;margin-left:4px;background:none;color:var(--muted);font-size:12px;text-decoration:underline;text-underline-offset:3px}
.processing button:hover{color:var(--blue)}
.result{display:flex;align-items:center;gap:14px;text-align:left}
.result img{flex:none;width:64px;height:64px;object-fit:cover;border-radius:5px;background:var(--theme-track)}
.video-details{min-width:0;flex:1}
.video-details h2{font-size:15px;font-weight:600;line-height:1.6;margin:0;overflow-wrap:anywhere}
.video-details p{font-size:12px;line-height:1.6;color:var(--muted);margin:3px 0 0;overflow-wrap:anywhere}
.result>button{font-size:13px;min-height:44px;padding:0 17px}
.result>button{background:var(--green)}
.result>button:hover:not(:disabled){background:var(--green-hover)}
.how-to{margin-top:96px;text-align:center}
.how-to>h2{font-size:24px;font-weight:600;margin:0 0 30px;line-height:1.4;letter-spacing:-.4px}
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:32px}
.tutorial-carousel.is-switcher{max-width:560px;margin:0 auto;touch-action:pan-y}
.is-switcher .carousel-window{overflow:hidden;border-radius:10px}
.is-switcher .steps{display:flex;gap:0;transform:translateX(var(--step-offset, -100%));transition:transform .45s cubic-bezier(.22,.68,.24,1)}
.is-switcher .steps.is-resetting{transition:none}
.is-switcher .step{flex:0 0 100%;min-width:0;min-height:240px;padding:32px 28px;display:flex;flex-direction:column;align-items:center;justify-content:center}
.tutorial-carousel.is-switcher:focus-visible{outline:3px solid var(--focus-border);outline-offset:4px;border-radius:10px}
.carousel-dots{display:flex;justify-content:center;align-items:center;gap:7px;height:8px;margin-top:20px}
.carousel-dots span{width:6px;height:6px;background:var(--field-border);border-radius:8px;transition:width .3s,background-color .3s}
.carousel-dots span.is-active{width:20px;background:var(--blue)}
.step{border:1px solid var(--line);border-radius:10px;padding:30px 23px 26px;text-align:center;min-height:210px;background:var(--surface)}
.step-label{display:inline-block;color:var(--badge-ink);background:var(--badge-bg);border-radius:3px;padding:2px 9px;font-size:12px;line-height:18px;font-weight:500;letter-spacing:.5px}
.step h3{font-size:20px;line-height:1.4;font-weight:600;margin:16px 0 12px;letter-spacing:-.25px}
.step p{font-size:15px;line-height:1.8;color:var(--muted);margin:0 auto;max-width:280px}
@keyframes spin{to{transform:rotate(360deg)}}
@keyframes download-nudge{0%,100%{transform:translateY(-1px)}50%{transform:translateY(2px)}}
@media(max-width:980px){.steps{gap:20px}.step{padding-left:18px;padding-right:18px}}
@media(max-width:800px){.how-to{margin-top:72px}.how-to>h2{margin-bottom:22px}.steps{grid-template-columns:1fr}.step{padding:28px 24px}}
@media(max-width:650px){.page-header{min-height:72px;padding:18px 20px 0}.theme-switch button{min-width:48px;min-height:48px}main{padding:0 20px 40px}.downloader{padding:46px 0 0}h1{font-size:28px}.intro{font-size:14px;line-height:1.7;margin:16px 0 30px}.link-field{padding:8px 8px 8px 13px;gap:8px;min-height:66px}.link-field input{font-size:16px}.link-field input::placeholder{font-size:16px}.link-field button{padding:0 16px;font-size:14px;min-height:48px}.how-to{margin-top:64px}.how-to>h2{font-size:22px;margin-bottom:22px}.step{padding:25px 22px}.step p{max-width:280px}.flow-panel{margin-top:14px;padding:14px}.flow-heading{margin-bottom:11px}.result{gap:11px;flex-wrap:wrap}.result img{width:56px;height:56px}.video-details h2{font-size:14px;line-height:1.5}.video-details p{font-size:12px}.result>button{width:100%;margin-top:2px;min-height:48px}.processing{font-size:13px;gap:7px}.status-notice{gap:8px;padding:10px 12px}.status-notice button{min-height:40px}#save-notice{gap:6px}#quota-retry{min-height:44px}}
@media(prefers-reduced-motion:reduce){.spinner,.flow-panel[data-state="downloading"] .flow-icon{animation:none}.is-switcher .steps,.carousel-dots span{transition:none}}
@media(max-width:380px){.link-field{flex-direction:column;align-items:stretch;padding:8px 12px;gap:4px}.link-field input{flex:auto;width:100%;height:44px}.link-field button{width:100%;min-height:44px}.progress-actions{gap:8px}}