:root{
    --bg:#f1f5f9; --card:#fff; --ink:#0f172a; --muted:#64748b; --line:#e2e8f0;
    --teal:#0f766e; --teal-d:#0b5d57; --green:#16a34a; --green-bg:#dcfce7;
    --red:#dc2626; --red-bg:#fee2e2; --amber:#d97706;
    --shadow:0 1px 3px rgba(0,0,0,.08),0 1px 2px rgba(0,0,0,.04);
    --radius:14px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
    font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
    background:var(--bg);color:var(--ink);line-height:1.45;-webkit-font-smoothing:antialiased;
}

/* ---------- Topbar ---------- */
.topbar{
    display:flex;align-items:center;justify-content:space-between;
    background:var(--teal);color:#fff;padding:12px 16px;position:sticky;top:0;z-index:10;
}
.topbar .brand{font-weight:700;font-size:1.1rem}
.topbar nav{display:flex;gap:6px}

.container{max-width:760px;margin:0 auto;padding:16px}

/* ---------- Buttons ---------- */
.btn{
    display:inline-flex;align-items:center;justify-content:center;gap:6px;
    border:0;border-radius:10px;padding:10px 16px;font-size:.95rem;font-weight:600;
    cursor:pointer;text-decoration:none;transition:.15s;font-family:inherit;
}
.btn-primary{background:var(--teal);color:#fff}
.btn-primary:hover{background:var(--teal-d)}
.btn-ghost{background:transparent;color:#fff;border:1px solid rgba(255,255,255,.4)}
.btn-ghost:hover{background:rgba(255,255,255,.12)}
.container .btn-ghost{color:var(--teal);border-color:var(--line)}
.container .btn-ghost:hover{background:var(--line)}
.btn-block{width:100%}
.link{color:var(--teal);text-decoration:none;font-size:.9rem}
.link:hover{text-decoration:underline}

/* ---------- Month nav ---------- */
.month-nav{display:flex;align-items:center;justify-content:center;gap:12px;margin:8px 0}
.month-title{font-size:1.4rem;margin:0;text-transform:capitalize;min-width:170px;text-align:center}
.month-nav .btn-ghost{font-size:1.5rem;padding:4px 14px;line-height:1}
.center{text-align:center;margin-bottom:8px}

/* ---------- Summary cards ---------- */
.cards{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin:16px 0}
.card{background:var(--card);border-radius:var(--radius);padding:16px;box-shadow:var(--shadow)}
.card-label{font-size:.8rem;color:var(--muted);font-weight:600}
.card-value{font-size:1.5rem;font-weight:700;margin-top:4px}
.card-sub{font-size:.75rem;color:var(--muted);margin-top:2px}
.card-total .card-value{color:var(--ink)}
.card-paid .card-value{color:var(--green)}
.card-remaining{background:var(--teal);color:#fff}
.card-remaining .card-label{color:rgba(255,255,255,.85)}

.progress{height:8px;background:var(--line);border-radius:99px;overflow:hidden;margin-bottom:16px}
.progress-bar{height:100%;background:var(--green);transition:width .3s}

.toolbar{display:flex;justify-content:flex-end;margin-bottom:12px}

/* ---------- List ---------- */
.list{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:8px}
.row{
    background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
    display:flex;align-items:center;gap:12px;padding:12px 14px;
}
.row.is-paid{opacity:.62}
.row.is-overdue{box-shadow:0 0 0 1.5px var(--red) inset,var(--shadow)}
.row-check{margin:0}
.checkbox{
    width:28px;height:28px;border-radius:50%;border:2px solid var(--line);background:#fff;
    cursor:pointer;font-size:1rem;color:#fff;display:flex;align-items:center;justify-content:center;
    font-weight:700;transition:.15s;flex-shrink:0;
}
.is-paid .checkbox{background:var(--green);border-color:var(--green)}
.row-main{flex:1;min-width:0}
.row-name{font-weight:600;display:flex;align-items:center;gap:6px;flex-wrap:wrap}
.is-paid .row-name{text-decoration:line-through}
.row-meta{font-size:.8rem;color:var(--muted);margin-top:2px}
.row-amount{font-weight:700;white-space:nowrap}
.row-actions{display:flex;gap:2px}
.icon-btn{background:transparent;border:0;cursor:pointer;font-size:1rem;padding:6px;border-radius:8px;color:var(--muted)}
.icon-btn:hover{background:var(--line)}
.row-actions form{margin:0}

.tag{font-size:.7rem;background:var(--line);color:var(--muted);padding:1px 7px;border-radius:99px;font-weight:600}
.tag-overdue{background:var(--red-bg);color:var(--red)}

.empty{background:var(--card);border-radius:var(--radius);padding:40px 20px;text-align:center;color:var(--muted);box-shadow:var(--shadow)}
.empty .btn{margin-top:12px}

/* ---------- Forms / labels ---------- */
label{display:block;font-weight:600;font-size:.9rem;margin-bottom:12px}
input[type=text],input[type=password],input[type=number]{
    width:100%;margin-top:5px;padding:11px 12px;border:1px solid var(--line);
    border-radius:10px;font-size:1rem;font-family:inherit;background:#fff;
}
input:focus{outline:2px solid var(--teal);border-color:var(--teal)}
.muted{color:var(--muted);font-weight:400;font-size:.85rem}
.radio-group{display:flex;flex-direction:column;gap:6px;margin-top:5px}
.radio{font-weight:400;display:flex;align-items:center;gap:8px;margin:0}
.radio input{width:auto;margin:0}

/* ---------- Alerts ---------- */
.alert{background:var(--red-bg);color:var(--red);padding:10px 14px;border-radius:10px;margin-bottom:14px;font-size:.9rem}
.alert-ok{background:var(--green-bg);color:var(--green)}

/* ---------- Modal ---------- */
.modal{
    display:none;position:fixed;inset:0;background:rgba(15,23,42,.5);z-index:50;
    align-items:flex-end;justify-content:center;padding:0;
}
.modal.open{display:flex}
.modal-card{
    background:#fff;border-radius:18px 18px 0 0;padding:22px;width:100%;max-width:520px;
    max-height:92vh;overflow:auto;animation:slideup .2s ease;
}
.modal-card h2{margin:0 0 16px}
.modal-actions{display:flex;gap:10px;justify-content:flex-end;margin-top:8px}
.modal-actions .btn-ghost{color:var(--muted);border:1px solid var(--line)}
@keyframes slideup{from{transform:translateY(30px);opacity:.6}to{transform:none;opacity:1}}

/* ---------- Login ---------- */
.login-page{display:flex;align-items:center;justify-content:center;min-height:100vh;padding:20px}
.login-card{background:#fff;border-radius:18px;box-shadow:0 10px 30px rgba(0,0,0,.12);padding:32px;width:100%;max-width:400px}
.login-card .brand{font-size:1.3rem;font-weight:700;color:var(--teal);margin-bottom:18px}
.login-card h1{font-size:1.3rem;margin:0 0 8px}
.login-card .muted{display:block;margin-bottom:18px}
.login-card .btn{margin-top:6px}

/* ---------- Responsive ---------- */
@media (min-width:560px){
    .modal{align-items:center;padding:20px}
    .modal-card{border-radius:18px}
}
@media (max-width:520px){
    .cards{grid-template-columns:1fr;gap:8px}
    .card{display:flex;align-items:baseline;justify-content:space-between;padding:14px 16px}
    .card-value{font-size:1.3rem;margin:0}
    .card-sub{display:none}
}