body {
    background-color: #f8f9fa;
}

.header {
    background: linear-gradient(to right, #007bff, #00aaff);
    color: white;
    padding: 1rem 0 0.5rem;
}

.header img {
    height: 85px;
}

.main-content {
    padding-bottom: 50px;
}

.form-box {
    background-color: white;
    border: 1px solid #dee2e6;
    border-top: 4px solid #007bff;
    border-radius: 6px;
    padding: 1rem;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.05);
}

.form-box h5 {
    margin-bottom: 1rem;
}

.form-control::placeholder {
    font-style: italic;
}

.input-group-text {
    background-color: #e9ecef;
}

.instructions {
    font-size: 0.95rem;
}

.footer {
    position: fixed;
    bottom: 0;
    width: 100% !important;
    background: linear-gradient(to right, #007bff, #00aaff);
    color: white;
}

.modal-header {
    background-color: #007bff;
    color: white;
    border-top-left-radius: .5rem;
    border-top-right-radius: .5rem;
}

.modal-content {
    border-radius: 0.75rem;
}

.modal-body i.bi-phone {
    font-size: 1.5rem;
    color: orange;
}

.modal-body .phone-number {
    font-weight: bold;
    color: orange;
}

.btn-yellow {
    background-color: #ffc107;
    color: black;
    font-weight: 500;
}

.btn-yellow:hover {
    background-color: #e0a800;
    color: white;
}

.otp-input {
    max-width: 300px;
    margin: 0 auto;
}

.text-right {
    text-align: right;
}

.syntax-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin: 20px 0;
}

/* item cú pháp */
.syntax {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 16px;
    border-radius: 10px;
    background: linear-gradient(135deg, #f8fbff, #eef3f9);
    font-weight: 600;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.syntax:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

/* nhãn DK/HUY/V/S/FW */
.syntax .code {
    display: inline-block;
    min-width: 40px;
    text-align: center;
    color: #fff;
    font-weight: 700;
    border-radius: 6px;
    padding: 4px 8px;
    font-size: 13px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.15);
    max-width: 100px;
}

/* nhãn DK/HUY/V/S/FW */
.syntax .syntax-content  {
    display: inline-block;
    min-width: 40px;
}


.syntax.dk .code {
    background: linear-gradient(135deg, #ff8a34, #f27115);
}

.syntax.huy .code {
    background: linear-gradient(135deg, #ff4e4e, #c92828);
}

.syntax.v .code {
    background: linear-gradient(135deg, #35c36a, #1f9c4f);
}

.syntax.s .code {
    background: linear-gradient(135deg, #2aa3ff, #1464c0);
}

.syntax.fw .code {
    background: linear-gradient(135deg, #8998b4, #5c6a84);
}

/* text cú pháp */
.syntax span {
    flex: 1;
    margin-left: 12px;
    color: #0b376f;
    font-size: 14px;
}

/* chữ Gửi 5656 */
.syntax .send {
    font-weight: 800;
    color: #0d3a74;
    font-size: 14px;
    white-space: nowrap;
    text-align: right;
    max-width: 70px;
}

/* block */
.syntax-block {
    margin-bottom: 24px;
}

.form-box h6 {
    margin: 0 0 12px;
    font-size: 15px;
    font-weight: 700;
    color: #133c7a;
    text-transform: uppercase;
    border-left: 4px solid #2aa3ff;
    padding-left: 8px;
}

/* nhóm nút hành động DK/HUY */
.syntax-actions {
    display: flex;
    gap: 14px;
    margin-top: 18px;
    flex-wrap: wrap;
}

.syntax-actions .btn {
    flex: 1;
    text-align: center;
    padding: 12px;
    border-radius: 10px;
    font-weight: 700;
    color: #fff;
    font-size: 14px;
    cursor: pointer;
    box-shadow: 0 3px 8px rgba(0, 0, 0, 0.15);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.syntax-actions .btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 14px rgba(0, 0, 0, 0.2);
}

.syntax-actions .btn.dk {
    background: linear-gradient(135deg, #ff8a34, #f27115);
}

.syntax-actions .btn.huy {
    background: linear-gradient(135deg, #ff4e4e, #c92828);
}

.syntax-actions .btn small {
    display: block;
    font-weight: 400;
    font-size: 12px;
    margin-top: 4px;
    opacity: 0.9;
}