:root {
    --primary: #4f46e5;
    --primary-hover: #4338ca;
    --bg: #f8fafc;
    --card-bg: #ffffff;
    --text: #1e293b;
    --text-light: #64748b;
    --border: #e2e8f0;
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
}

* { box-sizing: border-box; margin: 0; padding: 0; font-family: -apple-system, system-ui, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; }
body { background-color: var(--bg); color: var(--text); padding-bottom: 50px; line-height: 1.5; }

.header-bar { background-color: var(--primary); color: white; padding: 15px; text-align: center; position: sticky; top: 0; z-index: 100; box-shadow: 0 2px 4px rgba(0,0,0,0.1); }
.header-bar h1 { font-size: 20px; font-weight: 700; letter-spacing: 0.5px; }

/* Menu linh hoạt phản hồi tốt */
.nav-links { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px; background: #ffffff; padding: 12px; border-bottom: 1px solid var(--border); margin-bottom: 20px; }
.nav-links a { color: var(--text); text-decoration: none; font-size: 14px; font-weight: 500; padding: 6px 12px; border-radius: 6px; transition: all 0.2s; }
.nav-links a:hover { background: #f1f5f9; color: var(--primary); }
.nav-links a.admin-nav { color: var(--primary); font-weight: bold; background: #eef2ff; }

.container { width: 100%; max-width: 1100px; margin: 0 auto; padding: 0 15px; }
.card { background-color: var(--card-bg); border-radius: 12px; padding: 20px; margin-bottom: 20px; box-shadow: 0 4px 6px -1px rgba(0,0,0,0.05); border: 1px solid var(--border); }

/* Bố cục Grid thông minh hỗ trợ Responsive PC / iPad / Mobile */
.grid-2 { display: grid; grid-template-columns: 1fr; gap: 20px; }
@media (min-width: 768px) { .grid-2 { grid-template-columns: 1fr 1fr; } }

.form-group { margin-bottom: 15px; }
.form-group label { display: block; font-size: 14px; font-weight: 600; margin-bottom: 6px; color: var(--text); }
.form-control { width: 100%; padding: 10px 14px; border: 1px solid var(--border); border-radius: 8px; font-size: 15px; background-color: #fff; outline: none; transition: border 0.2s; }
.form-control:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1); }

/* Checklist Cards tối ưu trên di động */
.checklist-item { border-left: 5px solid #cbd5e1; transition: all 0.2s; }
.checklist-item.passed { border-left-color: var(--success); }
.checklist-item.failed { border-left-color: var(--danger); }
.checklist-item.skipped { border-left-color: var(--warning); }

.options-grid { display: flex; width: 100%; gap: 10px; margin-bottom: 10px; }
.option-cell { flex: 1; text-align: center; }
.option-cell label { display: block; padding: 12px 5px; border: 1px solid var(--border); border-radius: 8px; font-size: 14px; cursor: pointer; background: #f8fafc; font-weight: 500; }
.option-cell input[type="radio"]:checked + span { font-weight: 700; color: var(--primary); }

.btn { display: inline-block; width: 100%; padding: 12px; background-color: var(--primary); color: white; border: none; border-radius: 8px; font-size: 15px; font-weight: 600; text-align: center; cursor: pointer; text-decoration: none; transition: background 0.2s; }
.btn:hover { background-color: var(--primary-hover); }
.btn-secondary { background-color: #64748b; }
.btn-secondary:hover { background-color: #475569; }
.btn-success { background-color: var(--success); }
.btn-success:hover { background-color: #059669; }

/* Bảng hiển thị dữ liệu co giãn trên Windows PC nhưng trượt mượt trên mobile */
.table-responsive { width: 100%; overflow-x: auto; -webkit-overflow-scrolling: touch; border-radius: 8px; border: 1px solid var(--border); margin-top: 15px; }
table { width: 100%; border-collapse: collapse; background: white; font-size: 14px; min-width: 600px; }
th, td { border-bottom: 1px solid var(--border); padding: 12px 14px; text-align: left; }
th { background-color: #f1f5f9; font-weight: 600; color: var(--text-dark); }
tr:hover { background-color: #f8fafc; }

/* Làm mượt hiệu ứng cho toàn bộ nút bấm */
.btn {
    transition: all 0.2s ease-in-out;
    border-radius: 6px !important;
}
.btn:hover {
    transform: translateY(-1px);
    box-sizing: border-box;
    filter: brightness(90%);
}

/* Biến đổi ô Radio truyền thống thành nút bấm hiện đại dạng Thẻ */
.options-grid {
    display: flex;
    gap: 10px;
    margin-top: 8px;
}
.option-cell {
    flex: 1;
}
.option-cell label {
    display: block;
    text-align: center;
    padding: 10px;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.2s;
    background: #f8fafc;
}
/* Ẩn nút tròn radio gốc đi */
.option-cell input[type="radio"] {
    display: none;
}

/* Hiệu ứng active khi được tích chọn */
.option-cell input[type="radio"]:checked + span {
    color: white !important;
}
.option-cell:has(input[value="pass"]:checked) label {
    background-color: #10b981; border-color: #10b981; color: white;
}
.option-cell:has(input[value="fail"]:checked) label {
    background-color: #ef4444; border-color: #ef4444; color: white;
}
.option-cell:has(input[value="skip"]:checked) label {
    background-color: #f59e0b; border-color: #f59e0b; color: white;
}

/* Thanh Tiến Độ Thả Nổi Trên Điện Thoại */
.progress-sticky {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: rgba(15, 23, 42, 0.9);
    color: white;
    padding: 10px 15px;
    border-radius: 30px;
    font-size: 13px;
    font-weight: bold;
    z-index: 9999;
    box-shadow: 0 4px 12px rgba(0,0,0,0.3);
    display: flex;
    align-items: center;
    gap: 8px;
    backdrop-filter: blur(4px);
}