:root{--navy:#0b1f4d;--blue:#164ea6;--light:#f4f7fb;--border:#dbe3ef;--text:#172033;--muted:#68758a}
*{box-sizing:border-box}body{margin:0;font-family:Arial,Helvetica,sans-serif;background:var(--light);color:var(--text)}
a{text-decoration:none;color:inherit}.login-shell{min-height:100vh;display:grid;place-items:center;padding:24px;background:linear-gradient(135deg,#eef4ff,#f8fafc)}.login-card{width:min(430px,100%);background:#fff;border:1px solid var(--border);border-radius:18px;padding:30px;box-shadow:0 20px 60px rgba(11,31,77,.12)}.login-card h1{margin:0 0 8px;color:var(--navy);font-size:28px}.login-card p{color:var(--muted);margin:0 0 22px}.field{margin:14px 0}.field label{display:block;font-weight:700;font-size:13px;margin-bottom:7px}.field input{width:100%;padding:12px 13px;border:1px solid #cfd8e6;border-radius:9px;font-size:15px}.primary-btn{width:100%;border:0;border-radius:9px;padding:12px 16px;background:var(--blue);color:#fff;font-weight:700;font-size:15px;cursor:pointer}.login-error{min-height:20px;color:#b42318;font-size:13px;margin-top:10px}.back-link{display:inline-block;margin-top:18px;color:var(--blue);font-weight:700;font-size:14px}
.admin-layout{min-height:100vh;display:grid;grid-template-columns:245px 1fr}.admin-sidebar{background:var(--navy);color:#fff;padding:22px 16px;position:sticky;top:0;height:100vh}.admin-brand{font-size:18px;font-weight:800;padding:8px 10px 22px;border-bottom:1px solid rgba(255,255,255,.14)}.admin-brand small{display:block;font-weight:400;opacity:.72;margin-top:5px}.quick-title{font-size:11px;text-transform:uppercase;letter-spacing:.12em;opacity:.55;margin:24px 10px 8px}.side-link{display:block;padding:11px 12px;margin:5px 0;border-radius:9px;color:#fff;font-weight:700;font-size:14px}.side-link:hover,.side-link.active{background:rgba(255,255,255,.13)}.side-link.logout{margin-top:28px;color:#ffd6d6}.admin-main{min-width:0}.admin-topbar{height:68px;background:#fff;border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;padding:0 24px;position:sticky;top:0;z-index:5}.admin-topbar h1{font-size:20px;margin:0;color:var(--navy)}.admin-content{padding:24px}.welcome-card{background:#fff;border:1px solid var(--border);border-radius:14px;padding:26px;max-width:900px}.welcome-card h2{margin-top:0;color:var(--navy)}.invoice-frame{width:100%;height:calc(100vh - 116px);border:0;background:#fff;border-radius:12px;box-shadow:0 4px 18px rgba(11,31,77,.08)}
@media(max-width:760px){.admin-layout{grid-template-columns:1fr}.admin-sidebar{height:auto;position:relative}.admin-content{padding:12px}.invoice-frame{height:calc(100vh - 140px)}}