:root, :root[data-theme="light"] {
    --bg: #f8fafc; --card: #ffffff; --card-border: #e5e7eb; --ink: #0f172a;
    --muted: #6b7280; --header-bg: rgba(255,255,255,.92); --btn-hover-bg: #f3f4f6;
    --input-bg: #fff; --blue: #3b82f6; --green: #22c55e; --red: #ef4444;
    --orange: #f59e0b; --purple: #8b5cf6;
}
:root[data-theme="dark"] {
    --bg: #0b1220; --card: #0f1629; --card-border: #1b2540; --ink: #e6ecff;
    --muted: #8a99c2; --header-bg: rgba(15,22,41,.92); --btn-hover-bg: #0b1426;
    --input-bg: #0b1426;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; background: var(--bg); color: var(--ink); padding-top: 120px; }
a { color: var(--blue); text-decoration: none; }
.container { max-width: 1100px; margin: 0 auto; padding: 24px 16px; }
.header-container { background: var(--header-bg); backdrop-filter: blur(6px); border-bottom: 1px solid var(--card-border); position: fixed; top: 0; left: 0; right: 0; z-index: 200; }
.header-top { display: flex; justify-content: space-between; align-items: center; padding: 16px; max-width: 1100px; margin: 0 auto; }
.header-top h1 { font-size: 22px; }
.mode-toggle { display: flex; gap: 8px; }
.mode-btn { height: 36px; min-width: 44px; padding: 0 12px; border-radius: 9999px; border: 1px solid var(--card-border); background: var(--btn-hover-bg); color: inherit; font-weight: 700; cursor: pointer; font-size: 14px; display: inline-flex; align-items: center; justify-content: center; }
.mode-btn .icon { font-size: 18px; }
.mode-btn.active { background: rgba(37,99,235,.12); color: #1e40af; border-color: rgba(37,99,235,.25); }
.tabs { max-width: 1100px; margin: 0 auto; padding: 10px 16px 16px; overflow-x: auto; }
.tabs::-webkit-scrollbar { display: none; }
.tab-list { display: flex; gap: 10px; }
.tab { display: inline-block; padding: 10px 16px; border-radius: 9999px; border: 1px solid var(--card-border); color: inherit; background: transparent; font-size: 14px; font-weight: 700; white-space: nowrap; cursor: pointer; }
.tab:hover { background: rgba(37,99,235,.08); border-color: rgba(37,99,235,.25); color: var(--blue); }
.tab-logout:hover { background: rgba(239,68,68,.08); border-color: rgba(239,68,68,.25); color: var(--red); }
.tab.active { background: rgba(37,99,235,.10); border-color: rgba(37,99,235,.25); color: #2563eb; }

/* Cards */
.card { background: var(--card); border: 1px solid var(--card-border); border-radius: 12px; padding: 24px; margin-bottom: 16px; }
.card h2 { font-size: 18px; margin-bottom: 12px; }
.stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; margin-bottom: 24px; }
.stat { text-align: center; }
.stat .value { font-size: 28px; font-weight: 800; }
.stat .label { color: var(--muted); font-size: 13px; margin-top: 4px; }

/* Forms */
label { display: block; font-weight: 600; margin-bottom: 6px; font-size: 14px; }
input, select, textarea { width: 100%; padding: 10px 12px; border: 1px solid var(--card-border); border-radius: 8px; background: var(--input-bg); color: var(--ink); font-size: 14px; }
textarea { min-height: 100px; resize: vertical; }
.form-row { margin-bottom: 16px; }
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }

/* Buttons */
.btn { display: inline-flex; align-items: center; gap: 6px; padding: 10px 20px; border-radius: 8px; border: none; font-size: 14px; font-weight: 700; cursor: pointer; text-decoration: none; }
.btn-primary { background: var(--blue); color: #fff; }
.btn-primary:hover { opacity: .9; }
.btn-success { background: var(--green); color: #fff; }
.btn-danger { background: var(--red); color: #fff; }
.btn-outline { background: transparent; border: 1px solid var(--card-border); color: var(--ink); }
.btn-outline:hover { background: rgba(37,99,235,.08); border-color: rgba(37,99,235,.25); color: var(--blue); }
.btn-signout:hover { background: rgba(239,68,68,.08); border-color: rgba(239,68,68,.25); color: var(--red); }
.btn-sm { padding: 6px 12px; font-size: 13px; }

/* Table */
table { width: 100%; border-collapse: collapse; }
th, td { padding: 10px 12px; text-align: left; border-bottom: 1px solid var(--card-border); font-size: 14px; }
th { font-weight: 700; color: var(--muted); font-size: 12px; text-transform: uppercase; }

/* Status badges */
.badge { display: inline-block; padding: 4px 10px; border-radius: 9999px; font-size: 12px; font-weight: 700; }
.badge-draft { background: #f3f4f6; color: #6b7280; }
.badge-sent { background: #dbeafe; color: #1d4ed8; }
.badge-viewed { background: #fef3c7; color: #92400e; }
.badge-signed { background: #d1fae5; color: #065f46; }
.badge-paid_partial { background: #ede9fe; color: #5b21b6; }
.badge-paid_full { background: #dcfce7; color: #166534; }
.badge-completed { background: #f0fdf4; color: #14532d; }

/* Flash */
.flash { padding: 12px 16px; border-radius: 8px; margin-bottom: 16px; font-size: 14px; font-weight: 600; }
.flash-success { background: #d1fae5; color: #065f46; }
.flash-error { background: #fee2e2; color: #991b1b; }

/* Footer */
footer { text-align: center; padding: 24px; color: var(--muted); font-size: 13px; }

/* Responsive */
@media (max-width: 768px) {
    .form-grid { grid-template-columns: 1fr; }
    .stat-grid { grid-template-columns: 1fr 1fr; }
    body { padding-top: 130px; }
}