:root{--navy:#0B1F3A;--blue:#1B4D8C;--sky:#4DA3FF;--bg:#f3f6fb;--text:#1f2937;--muted:#6b7280;--card:#fff;--line:#e5e7eb;--ok:#059669}
*{box-sizing:border-box}body{margin:0;font-family:"Malgun Gothic","Apple SD Gothic Neo",system-ui,sans-serif;background:var(--bg);color:var(--text);line-height:1.65}
a{color:var(--blue);text-decoration:none}a:hover{text-decoration:underline}
.topbar{background:var(--navy);color:#fff;position:sticky;top:0;z-index:20}
.topbar-inner{max-width:1100px;margin:0 auto;padding:12px 18px;display:flex;align-items:center;justify-content:space-between;gap:12px}
.brand{font-weight:800;font-size:18px;color:#fff;text-decoration:none}
.top-actions{display:flex;gap:10px;align-items:center;flex-wrap:wrap}
.top-actions a{color:#dbeafe;font-size:13px}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:0;border-radius:10px;padding:11px 16px;font-weight:800;cursor:pointer;text-decoration:none}
.btn-sky{background:var(--sky);color:#08315c}
.btn-ghost{background:transparent;border:1px solid rgba(255,255,255,.35);color:#fff}
.btn-dark{background:var(--navy);color:#fff}
.btn-line{background:#fff;border:1px solid var(--line);color:var(--text)}
.btn-store{min-width:180px}
.wrap{max-width:1100px;margin:0 auto;padding:24px 18px 64px}
.hero{display:grid;grid-template-columns:1.2fr .9fr;gap:22px;align-items:stretch;margin-top:8px}
.hero-card,.login-card,.card{background:var(--card);border:1px solid var(--line);border-radius:16px;padding:22px;box-shadow:0 10px 30px rgba(15,23,42,.04)}
.hero-card h1{margin:0 0 10px;font-size:34px;color:var(--navy);letter-spacing:-.03em}
.hero-card p{margin:0;color:var(--muted)}
.store-row{display:flex;gap:10px;flex-wrap:wrap;margin-top:18px}
.login-card h2{margin:0 0 6px;font-size:18px;color:var(--navy)}
.login-card .sub{margin:0 0 14px;color:var(--muted);font-size:13px}
input{width:100%;padding:12px 12px;border:1px solid var(--line);border-radius:10px;margin-bottom:10px;font:inherit}
.err{color:#b91c1c;font-size:13px;min-height:18px;margin:0 0 8px}
.section{margin-top:28px}
.section h2{margin:0 0 10px;color:var(--navy);font-size:22px}
.grid3{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}
.feat{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:16px}
.feat h3{margin:0 0 6px;font-size:16px;color:var(--navy)}.feat p{margin:0;font-size:14px;color:var(--muted)}
.links{display:flex;gap:14px;flex-wrap:wrap;margin-top:10px}
footer{margin-top:40px;padding-top:18px;border-top:1px solid var(--line);color:var(--muted);font-size:13px;display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap}
.badge{display:inline-block;background:#e0f2fe;color:#075985;border-radius:999px;padding:3px 10px;font-size:12px;font-weight:700;margin-bottom:10px}
@media(max-width:860px){.hero,.grid3{grid-template-columns:1fr}.hero-card h1{font-size:28px}}
/* web app shell */
.app-shell{min-height:100vh;display:flex;flex-direction:column;background:#0B1220;color:#F3F6FB}
.app-top{padding:12px 16px;border-bottom:1px solid #243044;display:flex;justify-content:space-between;align-items:center}
.app-body{flex:1;display:grid;grid-template-columns:280px 1fr;min-height:0}
.chat-list,.chat-main{border-right:1px solid #243044;overflow:auto}
.chat-main{border-right:0;display:flex;flex-direction:column}
.chat-item{padding:12px 14px;border-bottom:1px solid #1e293b;cursor:pointer}
.chat-item:hover,.chat-item.active{background:#151D2E}
.msgs{flex:1;overflow:auto;padding:16px;display:flex;flex-direction:column;gap:8px}
.bubble{max-width:70%;padding:10px 12px;border-radius:14px;font-size:14px}
.bubble.me{align-self:flex-end;background:#1B4D8C}
.bubble.them{align-self:flex-start;background:#243044}
.composer{display:flex;gap:8px;padding:12px;border-top:1px solid #243044}
.composer input{margin:0;background:#0B1220;border-color:#243044;color:#fff}
@media(max-width:720px){.app-body{grid-template-columns:1fr}}