:root{
  --bg:#0f172a;--fg:#e5e7eb;--muted:#9ca3af;--card:#111827;--border:#1f2937;
  --accent:#2563eb;--accent-2:#7c3aed;--success:#16a34a;--danger:#dc2626;--warning:#d97706;
  --radius:12px;--radius-sm:10px;--shadow:0 6px 18px rgba(0,0,0,.12)
}
[data-theme="light"]{--bg:#f8fafc;--fg:#0f172a;--muted:#475569;--card:#ffffff;--border:#e2e8f0}
html,body{height:100%}
body{margin:0;background:var(--bg);color:var(--fg);font-family:system-ui,-apple-system,Segoe UI,Roboto,Ubuntu,Helvetica,Arial,sans-serif}
a{color:inherit;text-decoration:none}

/* Layout */
.container{max-width:1100px;margin:0 auto;padding:16px}
.header,.footer{background:rgba(0,0,0,.08);border-bottom:1px solid var(--border)}
.nav{display:flex;gap:12px;align-items:center;justify-content:space-between}
.nav-links{display:flex;gap:12px;align-items:center}
.brand{font-weight:700}

/* Cards */
.card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:16px;box-shadow:var(--shadow)}

/* Grid */
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:12px}
.row{display:flex;gap:12px;flex-wrap:wrap}
.mt-1{margin-top:8px}.mt-2{margin-top:12px}.mt-3{margin-top:16px}.mt-4{margin-top:24px}

/* Buttons */
.btn{display:inline-block;background:linear-gradient(135deg,var(--accent),var(--accent-2));color:#fff;padding:10px 14px;border-radius:var(--radius-sm);border:0;cursor:pointer;transition:transform .08s ease,filter .16s ease}
.btn:hover{filter:brightness(1.05)}
.btn:active{transform:translateY(1px)}
.btn-secondary{background:transparent;color:var(--fg);border:1px solid var(--border)}
.btn[disabled]{opacity:.6;cursor:not-allowed}
.spinner{display:inline-block;width:16px;height:16px;border:2px solid rgba(255,255,255,.35);border-top-color:#fff;border-radius:50%;animation:spin .8s linear infinite;vertical-align:middle;margin-left:8px}
@keyframes spin{to{transform:rotate(360deg)}}

/* Forms */
label{font-size:.9rem;color:var(--muted)}
input,select,textarea{background:transparent;color:var(--fg);border:1px solid var(--border);border-radius:var(--radius-sm);padding:10px;width:100%}
input:focus,select:focus,textarea:focus{outline:2px solid var(--accent);outline-offset:1px}
.field-error{color:var(--danger);font-size:.9rem}

/* Alerts */
.alert{border-radius:var(--radius-sm);padding:10px 12px;border:1px solid}
.alert-success{border-color:var(--success);color:var(--fg)}
.alert-error{border-color:var(--danger);color:var(--fg)}

/* Utilities */
.text-muted{color:var(--muted)}
.section-title{font-weight:700;font-size:1.25rem}
.hidden{display:none}

/* Theme toggle */
.theme-toggle{border:1px solid var(--border);border-radius:999px;padding:6px 10px}