body, html {
    margin: 0;
    padding: 0;
    height: 100%;
    overflow: hidden;
    font-family: 'Be Vietnam Pro', sans-serif;
    background-color: #000000;
}

/* --- Hiệu ứng nền --- */
.background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
}

#matrix-canvas {
    display: block;
}

/* --- Modal Overlay --- */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.6);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 2;
}

.modal {
    background-color: #161b22;
    border-radius: 20px;
    padding: 35px 45px;
    width: 90%;
    max-width: 520px;
    text-align: center;
    color: #c9d1d9;
    border: 1px solid #30363d;
    box-shadow: 0 10px 50px rgba(0, 0, 0, 0.8);
}

/* --- Nội dung trong Modal --- */
.modal h2 {
    color: #ffb800; /* Màu cam-vàng chủ đạo */
    font-size: 1.6em;
    font-weight: 700;
    margin-top: 0;
    margin-bottom: 20px;
    text-shadow: 0 0 10px rgba(255, 184, 0, 0.7);
}

.modal .subtitle, .modal .disclaimer, .btn-info {
    color: #8b949e;
    font-size: 0.95em;
}

.modal .age-gate {
    color: #f0f6fc;
    font-size: 1.15em;
    font-weight: 700;
    margin: 25px 0;
}

.modal .terms {
    color: #ffb800;
    margin: 30px 0 15px 0;
    font-weight: 700;
    text-shadow: 0 0 8px rgba(255, 184, 0, 0.5);
}

/* --- Checkbox tùy chỉnh --- */
.checkbox-container {
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 25px 0;
    cursor: pointer;
    font-size: 1em;
    user-select: none;
    color: #c9d1d9;
    font-weight: 500;
}

.checkbox-container input {
    display: none;
}

.checkbox-container .checkmark {
    position: relative;
    height: 22px;
    width: 22px;
    background-color: #0d1117;
    border-radius: 5px;
    margin-right: 12px;
    transition: background-color 0.2s, border-color 0.2s;
    border: 2px solid #30363d;
}

/* Kiểu khi checkbox được chọn */
.checkbox-container input:checked ~ .checkmark {
    background-color: #ffb800;
    border-color: #ffb800;
}

/* Dấu tick màu xanh */
.checkmark:after {
    content: "";
    position: absolute;
    display: none;
    left: 7px;
    top: 3px;
    width: 5px;
    height: 10px;
    border: solid #0d1117; /* Màu dấu tick */
    border-width: 0 3px 3px 0;
    transform: rotate(45deg);
}

.checkbox-container input:checked ~ .checkmark:after {
    display: block;
}

/* --- Nút bấm --- */
#continue-btn {
    background: #30363d;
    color: #8b949e;
    border: none;
    border-radius: 50px;
    padding: 16px 0;
    width: 100%;
    font-size: 1.2em;
    font-weight: 700;
    cursor: not-allowed;
    transition: all 0.3s ease;
    margin-top: 10px;
}

/* Kiểu khi nút được kích hoạt */
#continue-btn:disabled {
    opacity: 0.5;
}

#continue-btn:not(:disabled) {
    background: linear-gradient(180deg, #ffc94d, #ff9a00);
    color: #1c1c1c; /* Màu chữ tối để nổi bật trên nền cam */
    cursor: pointer;
    box-shadow: 0 0 20px rgba(255, 184, 0, 0.6);
}

#continue-btn:not(:disabled):hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 25px rgba(255, 184, 0, 0.8);
}

.btn-info {
    margin-top: 15px;
}