#include <bits/stdc++.h>
const int nRows = 21, nCols = 31;
int main() {
    freopen("input.txt", "rt", stdin);
    freopen("output.txt", "wt", stdout);
    std::vector a(nRows, std::vector(nCols, false));
    for (int r = 0; r < nRows; r++) {
        for (int c = 0; c < nCols; c++) {
            char t; std::cin >> t;
            a[r][c] = (t == '#');
        }
    }
    for (int c = 0; c < nCols; c++)
        for (int r = 0; r < nRows; r++) {
            std::cout << (a[r][c] ? char(0xFE) : char(0x00));
        }
}

For converting from site to text file you can save html webpage and parse elements mI_J, or you can save variable var from JS code. Order is column-major: $$$m_{0,0}, m_{1,0}, m_{2,0}, ..., m_{20,0}, m_{0,1}, ...$$$ .

Example in C++:

auto html2field(const char *fname) {
    std::ifstream fin(fname);
    std::string s;
    for(std::string line; std::getline(fin, line); s += line);
    int prev{};
    std::vector a(21, std::vector(31, false));
    for(int row = 0; row <= 20; row++) {
        for (int col = 0; col <= 30; col++) {
            char name[100];
            sprintf(name, "name=m%d_%d",row,col);
            int p1 = (int)s.find(name, prev);
            assert(p1 != (int)s.npos);
            int p2 = (int)s.find("src=img/", p1);
            assert(p2 != (int)s.npos);
            p2 += 8;
            bool isWall = (s.substr(p2,4) == "wall");
            a[row][col] = isWall;
        }
    }
    return a;
}