/* =====================================================================
   YT Thumbnail Downloader — professional light design (v4)
   Slate ink · indigo→sky brand · white surfaces · dark navy footer
   ===================================================================== */
:root{
  --bg:#F7F8FB; --bg-tint:#EEF1F8; --surface:#FFFFFF; --surface-2:#F8FAFC;
  --ink:#0F172A; --ink-2:#334155; --muted:#64748B; --line:#E2E8F0; --line-2:#EDF1F7;
  --brand:#4F46E5; --brand-2:#4338CA; --brand-soft:#EEF0FE; --sky:#0EA5E9;
  --good:#0E9F6E; --warn:#B45309;
  --yt:#FF0033; --fb:#1877F2; --ig:#E1306C; --tt:#0AB7AE; --tw:#0F1419; --vm:#17B5E8; --dm:#0A6CFF;
  --r:14px; --r-lg:20px; --r-xl:26px; --maxw:1140px;
  --display:"Plus Jakarta Sans","Segoe UI",system-ui,sans-serif;
  --body:"Inter","Segoe UI",system-ui,-apple-system,sans-serif;
  --grad:linear-gradient(120deg,var(--brand),var(--sky));
  --shadow:0 1px 2px rgba(15,23,42,.04),0 14px 40px -16px rgba(15,23,42,.18);
  --shadow-sm:0 1px 2px rgba(15,23,42,.05),0 8px 24px -16px rgba(15,23,42,.2);
  --shadow-lg:0 2px 4px rgba(15,23,42,.04),0 30px 60px -24px rgba(15,23,42,.28);
}
*{box-sizing:border-box}
html,body{max-width:100%;overflow-x:hidden}
html{scroll-behavior:smooth}
body{margin:0;font-family:var(--body);color:var(--ink-2);line-height:1.65;
  background:
    radial-gradient(720px 380px at 82% -6%,rgba(79,70,229,.10),transparent 60%),
    radial-gradient(680px 360px at 4% 2%,rgba(14,165,233,.09),transparent 58%),
    var(--bg);
  background-attachment:fixed;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
img{max-width:100%;display:block}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{width:100%;max-width:var(--maxw);margin:0 auto;padding:0 20px}

.site-head{position:sticky;top:0;z-index:60;background:rgba(247,248,251,.8);backdrop-filter:saturate(160%) blur(14px);border-bottom:1px solid var(--line)}
.site-head .wrap{display:flex;align-items:center;justify-content:space-between;height:68px;gap:10px}
.brand{display:flex;align-items:center;gap:9px;font-family:var(--display);font-weight:800;font-size:1.08rem;color:var(--ink);letter-spacing:-.02em;white-space:nowrap}
.brand:hover{text-decoration:none}
.brand .mark{width:36px;height:28px;border-radius:8px;background:var(--grad);display:grid;place-items:center;flex:0 0 auto;box-shadow:0 6px 18px -5px rgba(79,70,229,.55)}
.brand .mark::after{content:"";width:0;height:0;border-left:9px solid #fff;border-top:6px solid transparent;border-bottom:6px solid transparent;margin-left:3px}
.brand b{color:var(--brand);font-weight:800}
.nav{display:flex;align-items:center;gap:2px}
.nav a{color:var(--ink-2);font-weight:600;font-size:.9rem;padding:9px 12px;border-radius:10px}
.nav a:hover{background:var(--brand-soft);color:var(--brand);text-decoration:none}
.nav a.active{color:var(--brand)}
.menu-btn{display:none;background:var(--surface);border:1px solid var(--line);border-radius:10px;padding:10px 11px;cursor:pointer}
.menu-btn span,.menu-btn span::before,.menu-btn span::after{display:block;width:18px;height:2px;background:var(--ink);position:relative;border-radius:2px}
.menu-btn span::before,.menu-btn span::after{content:"";position:absolute;left:0}
.menu-btn span::before{top:-6px}.menu-btn span::after{top:6px}

.hero{padding:62px 0 18px}
.hero .eyebrow{display:inline-block;font-family:var(--display);font-weight:700;font-size:.74rem;letter-spacing:.14em;text-transform:uppercase;color:var(--brand);background:var(--brand-soft);border:1px solid #DCE0FB;padding:6px 13px;border-radius:999px;margin:0 0 18px}
.hero h1{font-family:var(--display);font-weight:800;font-size:clamp(2.1rem,5.4vw,3.5rem);line-height:1.05;letter-spacing:-.028em;margin:0 0 16px;max-width:18ch;color:var(--ink)}
.hero h1 em{font-style:normal;background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero .lede{font-size:1.12rem;color:var(--muted);max-width:60ch;margin:0}
.hero.center{text-align:center}
.hero.center h1{margin-left:auto;margin-right:auto}
.hero.center .lede{margin-left:auto;margin-right:auto}

.cards{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;margin:36px 0 8px}
.card{position:relative;display:block;background:var(--surface);border:1px solid var(--line);border-radius:var(--r-lg);padding:22px 18px 18px;box-shadow:var(--shadow-sm);overflow:hidden;transition:transform .16s,box-shadow .16s,border-color .16s;color:var(--ink)}
.card:hover{transform:translateY(-5px);text-decoration:none;border-color:color-mix(in srgb,var(--accent,var(--brand)) 45%,var(--line));box-shadow:0 22px 48px -22px color-mix(in srgb,var(--accent,var(--brand)) 55%,transparent)}
.card::before{content:"";position:absolute;inset:0 0 auto 0;height:4px;background:var(--accent,var(--brand))}
.card .ic{width:46px;height:46px;border-radius:13px;background:var(--accent,var(--brand));display:grid;place-items:center;color:#fff;font-family:var(--display);font-weight:800;font-size:1.1rem;margin-bottom:13px;box-shadow:0 8px 20px -8px color-mix(in srgb,var(--accent,var(--brand)) 70%,transparent)}
.card h3{font-family:var(--display);font-weight:700;font-size:1.06rem;margin:0 0 4px;color:var(--ink)}
.card p{margin:0;color:var(--muted);font-size:.88rem}
.card .go{margin-top:13px;font-family:var(--display);font-weight:700;font-size:.84rem;color:var(--accent,var(--brand));display:inline-flex;align-items:center;gap:6px}
.card .go::after{content:"→";transition:transform .15s}
.card:hover .go::after{transform:translateX(4px)}

.tool{margin:30px 0 6px}
.tool-card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r-xl);box-shadow:var(--shadow-lg);padding:26px}
.tool-card .tool-head{display:flex;align-items:center;gap:12px;margin-bottom:16px}
.tool-card .tool-head .ic{width:42px;height:42px;border-radius:12px;background:var(--accent,var(--brand));display:grid;place-items:center;color:#fff;font-family:var(--display);font-weight:800;flex:0 0 auto;box-shadow:0 8px 20px -8px color-mix(in srgb,var(--accent,var(--brand)) 70%,transparent)}
.tool-card .tool-head h2{font-family:var(--display);font-weight:700;font-size:1.14rem;margin:0;color:var(--ink)}
.input-row{display:flex;gap:9px;flex-wrap:wrap}
.input-row input{flex:1 1 240px;min-width:0;font-family:var(--body);font-size:1rem;color:var(--ink);padding:14px 15px;border:1.5px solid var(--line);border-radius:12px;background:var(--surface-2);transition:border-color .15s,box-shadow .15s}
.input-row input::placeholder{color:#94A0B3}
.input-row input:focus{outline:none;border-color:var(--accent,var(--brand));box-shadow:0 0 0 4px color-mix(in srgb,var(--accent,var(--brand)) 16%,transparent)}
.btn{font-family:var(--display);font-weight:700;font-size:.98rem;border:none;border-radius:12px;cursor:pointer;padding:14px 22px;display:inline-flex;align-items:center;justify-content:center;gap:8px;transition:transform .08s,filter .15s,background .15s}
.btn:active{transform:translateY(1px)}
.btn-primary{background:var(--accent,var(--brand));color:#fff;box-shadow:0 10px 24px -10px color-mix(in srgb,var(--accent,var(--brand)) 70%,transparent)}
.btn-primary:hover{filter:brightness(1.05)}
.btn-ghost{background:var(--surface-2);color:var(--ink-2);border:1px solid var(--line)}
.btn-ghost:hover{background:var(--bg-tint)}
.btn[disabled]{opacity:.55;cursor:progress}
.hint{font-size:.84rem;color:var(--muted);margin:12px 2px 0}
.hint code{background:var(--bg-tint);padding:2px 7px;border-radius:6px;font-size:.82rem;color:var(--ink-2)}
.platform-note{margin-top:14px;padding:12px 15px;border-radius:12px;background:#FFF7ED;border:1px solid #FCE3C2;color:var(--warn);font-size:.88rem;display:none}
.platform-note.show{display:block}
.status{margin-top:14px;font-size:.9rem;min-height:1.2em;color:var(--ink-2)}
.status.err{color:#C2410C}.status.ok{color:var(--good)}
.spinner{display:inline-block;width:15px;height:15px;vertical-align:-2px;border:2px solid var(--line);border-top-color:var(--accent,var(--brand));border-radius:50%;animation:spin .7s linear infinite;margin-right:7px}
@keyframes spin{to{transform:rotate(360deg)}}
.result{margin-top:20px;display:none}
.result.show{display:block}
.preview{position:relative;background:#0F172A;border:1px solid var(--line);border-radius:16px;padding:12px;overflow:hidden}
.viewport{position:relative;min-height:140px;display:grid;place-items:center;border-radius:10px;overflow:hidden;background:#0B1220}
.viewport img{max-width:100%;max-height:60vh;height:auto;object-fit:contain;border-radius:8px}
.quality-row{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px}
.chip{font-family:var(--display);font-size:.8rem;font-weight:700;padding:8px 13px;border-radius:999px;border:1.5px solid var(--line);background:var(--surface);color:var(--ink-2);cursor:pointer;transition:all .15s}
.chip:hover{border-color:var(--accent,var(--brand));color:var(--accent,var(--brand))}
.chip.active{background:var(--accent,var(--brand));color:#fff;border-color:var(--accent,var(--brand))}
.chip small{opacity:.7;font-weight:500}
.meta{margin-top:16px;display:flex;flex-direction:column;gap:9px}
.meta-row{display:none;gap:12px;align-items:flex-start;background:var(--surface-2);border:1px solid var(--line);border-radius:13px;padding:12px 14px}
.meta-row.show{display:flex}
.meta-l{flex:0 0 84px;font-family:var(--display);font-weight:700;font-size:.7rem;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);padding-top:3px}
.meta-v{flex:1 1 auto;min-width:0;color:var(--ink);font-size:.94rem;word-break:break-word;white-space:pre-wrap;max-height:200px;overflow:auto}
.meta-tags{display:flex;flex-wrap:wrap;gap:6px}
.meta-tags span{background:var(--brand-soft);border:1px solid #DCE0FB;color:var(--brand);font-size:.8rem;padding:4px 10px;border-radius:999px}
.meta-copy{flex:0 0 auto;background:var(--surface);border:1px solid var(--line);color:var(--ink-2);font-family:var(--display);font-weight:700;font-size:.74rem;padding:7px 11px;border-radius:9px;cursor:pointer;transition:all .14s}
.meta-copy:hover{border-color:var(--brand);color:var(--brand)}
.meta-note{font-size:.82rem;color:var(--muted);margin:2px 2px 0}
.actions{display:flex;flex-wrap:wrap;gap:9px;margin-top:16px}

.feat{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin:40px 0 8px}
.feat .item{background:var(--surface);border:1px solid var(--line);border-radius:var(--r-lg);padding:20px;box-shadow:var(--shadow-sm)}
.feat .item .n{font-family:var(--display);font-weight:800;color:var(--brand);font-size:.78rem;letter-spacing:.1em}
.feat .item h3{font-family:var(--display);font-size:1rem;margin:8px 0 6px;color:var(--ink)}
.feat .item p{margin:0;color:var(--muted);font-size:.9rem}

.article{padding:48px 0 12px}
.article .wrap{max-width:760px}
.article h2{font-family:var(--display);font-weight:800;letter-spacing:-.01em;font-size:clamp(1.5rem,3.6vw,2.05rem);line-height:1.2;margin:42px 0 14px;color:var(--ink)}
.article h2:first-child{margin-top:0}
.article h3{font-family:var(--display);font-weight:700;font-size:1.18rem;margin:28px 0 10px;color:var(--ink)}
.article p{margin:0 0 16px;color:var(--ink-2)}
.article ul,.article ol{margin:0 0 18px;padding-left:22px;color:var(--ink-2)}
.article li{margin-bottom:8px}
.article .lead{font-size:1.13rem;color:var(--ink)}
.article strong{color:var(--ink)}
.faq-q{font-weight:700;color:var(--ink);margin-bottom:4px}
.section-label{font-family:var(--display);font-weight:700;font-size:.76rem;letter-spacing:.13em;text-transform:uppercase;color:var(--brand);margin:0 0 10px}
.callout{background:var(--brand-soft);border:1px solid #DCE0FB;border-left:3px solid var(--brand);padding:16px 18px;border-radius:0 12px 12px 0;margin:22px 0}
.callout p{color:var(--ink-2)}
.callout p:last-child{margin-bottom:0}
.steps{counter-reset:s;list-style:none;padding:0;margin:22px 0}
.steps li{counter-increment:s;position:relative;padding:0 0 18px 52px;color:var(--ink-2)}
.steps li::before{content:counter(s);position:absolute;left:0;top:-2px;font-family:var(--display);font-weight:800;color:#fff;background:var(--grad);width:36px;height:36px;border-radius:11px;display:grid;place-items:center;font-size:1rem;box-shadow:0 8px 18px -8px rgba(79,70,229,.5)}
.steps li strong{display:block;color:var(--ink)}

.page-head{padding:54px 0 4px}
.page-head .wrap{max-width:760px}
.page-head h1{font-family:var(--display);font-weight:800;font-size:clamp(2rem,5vw,3rem);letter-spacing:-.025em;margin:14px 0 10px;color:var(--ink)}
.page-head p{color:var(--muted);font-size:1.08rem;margin:0;max-width:62ch}

.form-card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r-lg);padding:24px;box-shadow:var(--shadow-sm);margin:8px 0 26px}
.field{margin-bottom:16px}
.field label{display:block;font-weight:600;font-size:.9rem;margin-bottom:6px;color:var(--ink)}
.field input,.field textarea{width:100%;font-family:var(--body);font-size:1rem;color:var(--ink);padding:13px 14px;border:1.5px solid var(--line);border-radius:12px;background:var(--surface-2)}
.field textarea{resize:vertical;min-height:130px}
.field input::placeholder,.field textarea::placeholder{color:#94A0B3}
.field input:focus,.field textarea:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 4px rgba(79,70,229,.15)}
.contact-grid{display:grid;grid-template-columns:1.3fr 1fr;gap:24px;align-items:start}
.info-card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r-lg);padding:20px;box-shadow:var(--shadow-sm)}
.info-card h3{font-family:var(--display);margin:0 0 4px;font-size:1.02rem;color:var(--ink)}
.info-card p{margin:0 0 14px;color:var(--muted);font-size:.92rem}
.info-card strong{color:var(--brand)}

.site-foot{margin-top:60px;background:#0F172A;color:#CBD5E1}
.site-foot .wrap{padding:48px 20px 28px}
.foot-grid{display:grid;grid-template-columns:1.7fr 1fr 1fr 1fr;gap:26px}
.site-foot .brand{color:#fff;margin-bottom:12px}
.site-foot .brand b{color:#A5B4FC}
.site-foot p{color:#94A3B8;font-size:.9rem;max-width:38ch}
.foot-col h4{font-family:var(--display);color:#fff;font-size:.76rem;letter-spacing:.12em;text-transform:uppercase;margin:4px 0 14px}
.foot-col a{display:block;color:#CBD5E1;padding:5px 0;font-size:.92rem}
.foot-col a:hover{color:#fff}
.foot-bottom{border-top:1px solid #1E293B;margin-top:32px;padding-top:20px;display:flex;justify-content:space-between;flex-wrap:wrap;gap:10px;font-size:.83rem;color:#7C8BA1}

.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);border:0}
:focus-visible{outline:2px solid var(--brand);outline-offset:2px}
@media (prefers-reduced-motion:reduce){*{animation-duration:.001ms!important;transition-duration:.001ms!important;scroll-behavior:auto!important}}

@media (max-width:960px){.cards{grid-template-columns:repeat(2,1fr)}.feat{grid-template-columns:1fr}.foot-grid{grid-template-columns:1fr 1fr}.contact-grid{grid-template-columns:1fr}}
@media (max-width:680px){
  .nav{display:none;position:absolute;top:68px;left:0;right:0;flex-direction:column;background:var(--surface);border-bottom:1px solid var(--line);padding:10px 14px;gap:2px;box-shadow:var(--shadow)}
  .nav.open{display:flex}.nav a{padding:13px 12px}.menu-btn{display:inline-flex}
  .hero{padding:40px 0 16px}.tool-card{padding:18px}
  .input-row input{flex:1 1 100%}.input-row .btn{flex:1 1 auto}
  .cards{gap:12px}.foot-grid{grid-template-columns:1fr 1fr;gap:18px}
  .meta-row{flex-wrap:wrap}.meta-l{flex-basis:100%}.meta-copy{order:3}
}
@media (max-width:430px){.cards{grid-template-columns:1fr}.brand{font-size:1rem}.brand .mark{width:32px;height:25px}}