/* dev-run.sody.co.kr — Tutti Run 특허 회피 아이디어 데모 (2026-10-25). 토큰 = run.sody.co.kr v5 (tools/site_v5.css) */
:root{
  --bg:#0A0A0B;--surface:#151517;--surface2:#1E1E21;--line:#2A2A2E;--text:#F4F4F2;--dim:#8E8E93;--off:#4A4A50;
  --spot:#FF5A1F;--spot-fill:rgba(255,90,31,.18);--ok:#3DDC84;
  --num:"Barlow Condensed",sans-serif;
  --ko:"Pretendard Variable",Pretendard,-apple-system,BlinkMacSystemFont,"Apple SD Gothic Neo","Noto Sans KR",sans-serif;
  --ease-out:cubic-bezier(.23,1,.32,1);--ease-io:cubic-bezier(.77,0,.175,1);
  --gut:clamp(16px,4vw,48px);--k:12px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{background:var(--bg);-webkit-text-size-adjust:100%}
body{background:var(--bg);color:var(--text);font-family:var(--ko);font-size:16px;line-height:1.6;-webkit-font-smoothing:antialiased;overflow-x:hidden;word-break:keep-all}
a{color:inherit}
button{font:inherit;color:inherit;background:none;border:0;cursor:pointer}
:focus-visible{outline:2px solid var(--spot);outline-offset:3px}
.wrap{max-width:1080px;margin:0 auto;padding:0 var(--gut)}
.num{font-family:var(--num);font-weight:700;font-style:italic;font-variant-numeric:tabular-nums}
.eyebrow{font:600 13px var(--num);letter-spacing:.16em;text-transform:uppercase;color:var(--spot)}
.eyebrow .ko{font:500 13px var(--ko);letter-spacing:0;color:var(--dim);margin-left:8px;text-transform:none}
h1{font-size:clamp(32px,5vw,56px);line-height:1.12;letter-spacing:-.03em;font-weight:700}
h2{font-size:clamp(24px,3.2vw,36px);line-height:1.2;letter-spacing:-.02em;font-weight:700}
h1 em,h2 em{font-style:normal;color:var(--spot)}
.lead{color:var(--dim);font-size:clamp(15px,1.3vw,18px);max-width:36em;margin-top:14px}
.slant{clip-path:polygon(var(--k) 0,100% 0,calc(100% - var(--k)) 100%,0 100%)}

/* 위 띠 */
.top{position:sticky;top:0;z-index:20;height:56px;display:flex;align-items:center;background:rgba(10,10,11,.85);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.top .wrap{display:flex;align-items:center;gap:16px;width:100%}
.brand{font:italic 700 20px var(--num);text-transform:uppercase;letter-spacing:.02em;text-decoration:none}
.brand b{color:var(--spot)}
.top .tag{font:600 12px var(--num);letter-spacing:.14em;color:var(--dim);border:1px solid var(--line);padding:3px 8px}
.top nav{margin-left:auto;display:flex;gap:4px}
.top nav a{font:italic 700 15px var(--num);text-decoration:none;color:var(--dim);width:30px;height:30px;display:grid;place-items:center;transition:color 150ms ease,background-color 150ms ease}
.top nav a[aria-current]{color:#000;background:var(--spot)}
@media (hover:hover) and (pointer:fine){.top nav a:hover{color:var(--text)}}

/* 버튼 */
.btn{--k:10px;display:inline-flex;align-items:center;justify-content:center;gap:8px;height:48px;padding:0 24px;font:600 15px var(--ko);text-decoration:none;background:var(--surface2);clip-path:polygon(var(--k) 0,100% 0,calc(100% - var(--k)) 100%,0 100%);transition:background-color 150ms ease,color 150ms ease,transform 120ms var(--ease-out);user-select:none;-webkit-user-select:none}
.btn.solid,.btn[aria-pressed="true"]{background:var(--spot);color:#000}
.btn:active{transform:scale(.97)}
@media (hover:hover) and (pointer:fine){.btn:hover{background:#2A2A2E}.btn.solid:hover,.btn[aria-pressed="true"]:hover{background:#FF7240}}
.btn svg{width:18px;height:18px;fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}

/* 섹션 */
.hero{padding:clamp(40px,7vw,88px) 0 28px}
.stage{background:var(--surface);padding:clamp(18px,3vw,32px);margin-top:28px;position:relative;overflow:hidden}
.row{display:flex;align-items:center;gap:12px;flex-wrap:wrap}
.hint{font-size:13px;color:var(--dim)}

/* 악기 칸 (앱 SeatBlock 과 같은 모양) */
.seats{display:grid;grid-template-columns:repeat(7,1fr);gap:6px;margin-top:20px}
.seat{--k:12px;position:relative;aspect-ratio:.68;background:var(--surface2);clip-path:polygon(var(--k) 0,100% 0,calc(100% - var(--k)) 100%,0 100%);display:flex;flex-direction:column;align-items:center;justify-content:center;gap:6px;padding:6px 4px;overflow:hidden}
.seat .glow{position:absolute;inset:0;background:var(--spot);transform:translateY(101%);transition:transform 300ms var(--ease-out)}
.seat svg{position:relative;width:26px;height:26px;fill:none;stroke:var(--off);stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round;transition:stroke 200ms ease-out}
.seat b{position:relative;font-size:12px;font-weight:600;color:var(--dim);text-align:center;line-height:1.25;transition:color 200ms ease-out}
.seat .n{position:absolute;left:14px;top:6px;font:italic 700 13px var(--num);color:var(--off);transition:color 200ms ease-out}
.seat.on .glow{transform:none}
.seat.on svg{stroke:#000}.seat.on b,.seat.on .n{color:#000}
@media (max-width:640px){.seats{grid-template-columns:repeat(7,1fr);gap:3px}.seat{--k:7px;aspect-ratio:.5}.seat svg{width:18px;height:18px}.seat b{font-size:10px}.seat .n{left:8px;font-size:11px}}
.cap{margin-top:12px;font-size:14px;color:var(--dim);min-height:1.6em}
.cap b{color:var(--spot)}

/* 특허 고리 도식: 센서 → 규칙 → 음악, 끊긴 고리 */
.chain{display:grid;grid-template-columns:1fr auto 1fr auto 1fr;align-items:center;gap:8px;margin-top:22px}
.chain .node{background:var(--surface2);padding:12px 10px;text-align:center;font-size:14px;font-weight:600;--k:10px;clip-path:polygon(var(--k) 0,100% 0,calc(100% - var(--k)) 100%,0 100%)}
.chain .node small{display:block;font-size:11px;font-weight:500;color:var(--dim)}
.chain .node.hot{background:var(--spot);color:#000}.chain .node.hot small{color:rgba(0,0,0,.65)}
.chain .link{position:relative;width:clamp(28px,6vw,64px);height:2px;background:var(--off)}
.chain .link i{position:absolute;inset:0;background:var(--text);transform-origin:left;transform:scaleX(0)}
.chain .link.cut i{background:var(--off)}
.chain .link .x{position:absolute;left:50%;top:50%;width:22px;height:22px;margin:-11px 0 0 -11px;opacity:0}
.chain .link .x::before,.chain .link .x::after{content:"";position:absolute;left:50%;top:0;width:3px;height:100%;margin-left:-1.5px;background:var(--spot);transform:rotate(45deg)}
.chain .link .x::after{transform:rotate(-45deg)}
.chain.play .link i{transform:none;transition:transform 500ms var(--ease-out)}
.chain.play .link:nth-of-type(4) i{transition-delay:300ms}
.chain.play .link.cut .x{opacity:1;transform:scale(1);transition:opacity 200ms ease-out 650ms,transform 300ms var(--ease-out) 650ms}
.chain .link.cut .x{transform:scale(1.4)}
.chain-note{margin-top:12px;font-size:13px;color:var(--dim)}
.chain-note b{color:var(--text)}

/* 슬라이더 */
.range{display:flex;align-items:center;gap:14px;margin-top:18px}
.range input{flex:1;accent-color:var(--spot);height:28px}
.range output{min-width:5.2em;text-align:right;font:italic 700 26px var(--num)}
.range label{font:600 12px var(--num);letter-spacing:.14em;color:var(--dim)}

/* 등장 */
.js [data-rv]{opacity:0;transform:translateY(16px);transition:opacity 500ms var(--ease-out),transform 500ms var(--ease-out);transition-delay:calc(var(--i,0) * 60ms)}
.js [data-rv].in{opacity:1;transform:none}

/* 정보 상자 */
.why{margin-top:28px;border-top:3px solid var(--spot);padding-top:16px;display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.why h3{font-size:15px;font-weight:700;margin-bottom:4px}
.why p{font-size:14px;color:var(--dim)}
@media (max-width:760px){.why{grid-template-columns:1fr}}
footer{border-top:1px solid var(--line);margin-top:72px;padding:28px 0 48px;font-size:12px;color:var(--dim)}

@media (prefers-reduced-motion:reduce){
  .js [data-rv]{transform:none}
  .seat .glow{transition:none}
  .chain.play .link.cut .x,.chain .link.cut .x{transform:none}
  .btn:active{transform:none}
}