/* === CASE STUDY: Google Pay — Budget Management === */
/* Extends css/style.css tokens; no new colors introduced. */

.cs-wrap{max-width:1040px;margin:0 auto;}

.cs-back{display:inline-flex;align-items:center;gap:8px;font-size:.72rem;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--text-3);text-decoration:none;font-family:var(--mono);transition:color .25s,gap .3s var(--ease);margin-bottom:32px;}
.cs-back:hover{color:var(--accent-text);gap:12px;}

/* Hero */
#cs-hero{padding-top:150px;}
.cs-h1{font-size:clamp(2.2rem,5vw,3.4rem);font-weight:900;letter-spacing:-.03em;line-height:1.08;color:var(--text);text-wrap:balance;margin-bottom:22px;}
.cs-h1 .acc{color:var(--accent-text);}
.cs-dek{font-size:1.05rem;line-height:1.72;color:var(--text-2);max-width:640px;margin-bottom:28px;}
.cs-tags{display:flex;flex-wrap:wrap;gap:10px;margin-bottom:36px;}

.cs-meta{display:flex;flex-wrap:wrap;gap:32px 48px;padding-top:28px;border-top:1px solid var(--border);}
.cs-meta div{display:flex;flex-direction:column;gap:6px;}
.cs-meta-label{font-size:.62rem;font-weight:700;letter-spacing:.16em;text-transform:uppercase;color:var(--text-3);font-family:var(--mono);}
.cs-meta-value{font-size:.92rem;font-weight:700;color:var(--text);}

/* Problem / Solution pair */
.cs-pair{display:grid;grid-template-columns:1fr 1fr;gap:56px;}
.cs-h3{font-size:1.15rem;font-weight:800;letter-spacing:-.02em;color:var(--text);margin-bottom:14px;}
.cs-p{font-size:.92rem;line-height:1.76;color:var(--text-2);}

.cs-pain{list-style:none;margin-top:16px;display:flex;flex-direction:column;gap:9px;}
.cs-pain li{position:relative;padding-left:18px;font-size:.82rem;line-height:1.55;color:var(--text-3);}
.cs-pain li::before{content:'';position:absolute;left:0;top:.55em;width:6px;height:1px;background:var(--accent);}

.cs-insight{margin-top:48px;padding-top:40px;border-top:1px solid var(--border);max-width:720px;}

/* Information architecture tree */
:root{--ia-line:#65678F;}
@media(prefers-color-scheme:light){:root{--ia-line:#7A78A0;}}
:root[data-theme=dark]{--ia-line:#65678F;}
:root[data-theme=light]{--ia-line:#7A78A0;}

.ia-wrap{overflow-x:auto;padding:8px 4px 20px;scrollbar-width:thin;}
.ia-wrap::-webkit-scrollbar{height:6px;}
.ia-wrap::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px;}

.ia-tree{display:inline-block;min-width:100%;}
.ia-tree ul{display:flex;justify-content:center;padding-top:28px;position:relative;}
.ia-tree > ul{padding-top:0;}
.ia-tree li{list-style:none;position:relative;padding:28px 8px 0;text-align:center;}
.ia-tree li::before,.ia-tree li::after{content:'';position:absolute;top:0;right:50%;width:50%;height:28px;border-top:1px solid var(--ia-line);}
.ia-tree li::after{right:auto;left:50%;border-left:1px solid var(--ia-line);}
.ia-tree li:only-child{padding-top:0;}
.ia-tree li:only-child::before,.ia-tree li:only-child::after{display:none;}
.ia-tree li:first-child::before,.ia-tree li:last-child::after{border:0 none;}
.ia-tree li:last-child::before{border-right:1px solid var(--ia-line);border-radius:0 6px 0 0;}
.ia-tree li:first-child::after{border-radius:6px 0 0 0;}
.ia-tree ul ul::before{content:'';position:absolute;top:0;left:50%;width:0;height:28px;border-left:1px solid var(--ia-line);}

.ia-node{display:inline-block;padding:9px 14px;border-radius:100px;border:1px solid var(--ia-line);background:var(--card);color:var(--text);font-size:.74rem;font-weight:700;white-space:nowrap;}
.ia-root{background:var(--accent);border-color:var(--accent);color:var(--on-accent);}
.ia-leaf{background:var(--surface);border-style:dashed;color:var(--text-2);font-weight:600;}

/* Flow */
.cs-stages{display:flex;flex-direction:column;gap:48px;margin-top:8px;}
.cs-stage-label{display:flex;flex-wrap:wrap;align-items:baseline;gap:12px;margin-bottom:20px;}
.cs-stage-name{font-size:.72rem;font-weight:800;letter-spacing:.14em;text-transform:uppercase;color:var(--text);font-family:var(--mono);}
.cs-stage-cap{font-size:.85rem;color:var(--text-3);}

.cs-film{display:flex;gap:16px;overflow-x:auto;padding:4px 4px 14px;scrollbar-width:thin;}
.cs-film::-webkit-scrollbar{height:6px;}
.cs-film::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px;}

.cs-screen{flex:0 0 auto;width:150px;display:flex;flex-direction:column;gap:10px;}
.cs-screen .frm{width:150px;height:325px;border-radius:16px;overflow:hidden;background:var(--card);border:1px solid var(--border);box-shadow:0 14px 34px -14px rgba(0,0,0,.5);}
.cs-screen .frm img{width:100%;height:100%;object-fit:cover;display:block;}
.cs-screen .lbl{font-size:.72rem;color:var(--text-3);text-align:center;}

/* Features */
.cs-fgrid{display:grid;grid-template-columns:repeat(3,1fr);gap:1px;background:var(--border);border:1px solid var(--border);border-radius:var(--r);overflow:hidden;}
.cs-fcard{background:var(--surface);padding:30px 26px;}
.cs-fcard .num{font-family:var(--mono);font-weight:700;font-size:.7rem;color:var(--accent-text);letter-spacing:.08em;}
.cs-fcard h3{font-size:.98rem;font-weight:800;color:var(--text);margin:12px 0 8px;}
.cs-fcard p{font-size:.82rem;color:var(--text-2);line-height:1.6;}

.cs-next{display:flex;align-items:center;gap:18px;margin-top:44px;padding-top:32px;border-top:1px solid var(--border);}
.cs-next-tag{flex-shrink:0;font-family:var(--mono);font-size:.62rem;font-weight:700;letter-spacing:.12em;text-transform:uppercase;color:var(--accent-text);border:1px solid var(--border-h);border-radius:100px;padding:7px 14px;}
.cs-next p{font-size:.88rem;color:var(--text-2);}

.cs-learn{list-style:none;display:flex;flex-direction:column;gap:16px;max-width:720px;margin-bottom:8px;}
.cs-learn li{position:relative;padding-left:22px;font-size:.92rem;line-height:1.7;color:var(--text-2);}
.cs-learn li::before{content:'';position:absolute;left:0;top:.65em;width:10px;height:1px;background:var(--accent);}

.cs-endlink{margin-top:56px;text-align:center;}

@media(max-width:900px){
  #cs-hero{padding-top:120px;}
  .cs-pair{grid-template-columns:1fr;gap:32px;}
  .cs-fgrid{grid-template-columns:1fr;}
  .cs-meta{gap:20px 32px;}
}