:root {
    --bg: #f5f6f8;
    --panel: #ffffff;
    --border: #e1e4e9;
    --text: #1f2430;
    --muted: #6b7280;
    --accent: #2f5fda;
    --accent-dark: #1e3fa0;
    --danger: #d64545;
    --radius: 10px;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
}

a { color: var(--accent); text-decoration: none; }

.topbar {
    display: flex;
    align-items: center;
    gap: 24px;
    padding: 12px 24px;
    background: var(--panel);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 10;
}
.topbar .brand { font-weight: 700; font-size: 17px; }
.topbar nav { display: flex; gap: 18px; flex: 1; }
.topbar nav a { color: var(--muted); font-weight: 600; padding: 6px 2px; border-bottom: 2px solid transparent; position: relative; }
.topbar nav a.active, .topbar nav a:hover { color: var(--text); border-bottom-color: var(--accent); }
.badge {
    display: inline-block;
    background: var(--accent);
    color: #fff;
    border-radius: 999px;
    font-size: 11px;
    padding: 1px 7px;
    margin-left: 4px;
    vertical-align: middle;
}
.logout-link { color: var(--muted); font-size: 14px; }

.app-main { max-width: 1180px; margin: 0 auto; padding: 24px; }

.login-body { display: flex; align-items: center; justify-content: center; height: 100vh; background: var(--bg); }
.login-card {
    background: var(--panel);
    padding: 32px;
    border-radius: var(--radius);
    box-shadow: 0 2px 12px rgba(0,0,0,0.06);
    width: 320px;
    display: flex;
    flex-direction: column;
    gap: 14px;
}
.login-card h1 { font-size: 18px; margin: 0 0 4px; }
.login-card label { display: flex; flex-direction: column; gap: 6px; font-size: 13px; color: var(--muted); }
.login-card input {
    padding: 9px 10px;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 14px;
}
.login-card button {
    background: var(--accent);
    color: #fff;
    border: none;
    padding: 10px;
    border-radius: 6px;
    font-weight: 600;
    cursor: pointer;
}
.login-card button:hover { background: var(--accent-dark); }
.login-card .error { color: var(--danger); font-size: 13px; margin: 0; }

.dash-summary { display: flex; gap: 16px; margin-bottom: 20px; }
.summary-card {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 24px;
    display: flex;
    flex-direction: column;
}
.summary-card .num { font-size: 28px; font-weight: 700; }
.summary-card .label { color: var(--muted); font-size: 13px; }

.dash-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.chart-card {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 18px;
}
.chart-card.wide { grid-column: 1 / -1; }
.chart-card h3 { margin: 0 0 12px; font-size: 14px; color: var(--muted); text-transform: uppercase; letter-spacing: .04em; }
.hint { color: var(--muted); font-size: 13px; margin-top: 16px; }

.layout-2col { display: grid; grid-template-columns: 1fr 300px; gap: 20px; align-items: start; }

.filter-bar {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 14px 16px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 16px;
}
.filter-bar select, .filter-bar input[type="text"] {
    padding: 7px 8px;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 13px;
}
.filter-bar input[type="text"] { flex: 1; min-width: 180px; }
.filter-bar button {
    padding: 7px 12px;
    border-radius: 6px;
    border: 1px solid var(--border);
    background: #fff;
    cursor: pointer;
    font-size: 13px;
}

.q-list { display: flex; flex-direction: column; gap: 10px; }
.q-card {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 14px 16px;
    display: flex;
    gap: 12px;
}
.q-card input[type="checkbox"] { margin-top: 3px; }
.q-card .tags { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 6px; }
.tag {
    font-size: 11px;
    padding: 2px 8px;
    border-radius: 999px;
    background: #eef1f8;
    color: var(--accent-dark);
    font-weight: 600;
}
.tag.difficulty-Easy { background: #e6f7ee; color: #1a7f4b; }
.tag.difficulty-Medium { background: #fff4e0; color: #a86400; }
.tag.difficulty-Hard { background: #fde9e9; color: #b3261e; }
.q-card .stem { font-size: 14px; line-height: 1.5; }
.q-card .options { margin-top: 8px; font-size: 13px; color: var(--muted); display: grid; grid-template-columns: 1fr 1fr; gap: 4px 12px; }

.pagination { display: flex; gap: 8px; align-items: center; justify-content: center; margin-top: 18px; }
.pagination button {
    padding: 6px 12px;
    border-radius: 6px;
    border: 1px solid var(--border);
    background: #fff;
    cursor: pointer;
}
.pagination button:disabled { opacity: .4; cursor: default; }

.cart-panel {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px;
    position: sticky;
    top: 76px;
}
.cart-panel h3 { margin-top: 0; font-size: 14px; }
.cart-item { display: flex; justify-content: space-between; gap: 8px; font-size: 13px; padding: 6px 0; border-bottom: 1px solid var(--border); }
.cart-item button { border: none; background: none; color: var(--danger); cursor: pointer; font-size: 12px; }

.btn { display: inline-block; padding: 9px 16px; border-radius: 6px; border: none; background: var(--accent); color: #fff; font-weight: 600; cursor: pointer; font-size: 14px; }
.btn:hover { background: var(--accent-dark); }
.btn.secondary { background: #fff; color: var(--text); border: 1px solid var(--border); }
.btn:disabled { opacity: .5; cursor: default; }

.test-form { display: flex; flex-direction: column; gap: 10px; margin-top: 12px; }
.test-form input[type="text"] { padding: 8px; border: 1px solid var(--border); border-radius: 6px; }
.test-form label { font-size: 13px; display: flex; align-items: center; gap: 6px; }

.tests-table { width: 100%; border-collapse: collapse; background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.tests-table th, .tests-table td { padding: 10px 14px; border-bottom: 1px solid var(--border); text-align: left; font-size: 14px; }
.tests-table th { color: var(--muted); font-size: 12px; text-transform: uppercase; }
.tests-table tr:last-child td { border-bottom: none; }

.empty-state { text-align: center; color: var(--muted); padding: 40px 0; }