Nginx configure https to display unsafe links

use openssl to automatically generate keys locally, and access tests show insecure connections. How to solve this problem?
configuration file is as follows:
server {

    listen      443;
    server_name  localhost;
    **ssl on;                                
    ssl_certificate ssl/server.crt;        
    ssl_certificate_key ssl/server.key;    
    ssl_protocols SSLv2 SSLv3 TLSv1;
    ssl_ciphers ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP;
    ssl_prefer_server_ciphers on;**
    -sharpcharset koi8-r;

    -sharpaccess_log  logs/host.access.log  main;

    location / {
        root   html;
        index  index.html index.htm;
    }

}
access test results are as follows:

Mar.04,2021

because you don't have a certificate configured, you can learn that Let's Encrypt, can get a free certificate

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1be636e-31032.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1be636e-31032.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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