[Cruze]

You can try this. I don't know much about CSS. Gathered all these up from the internet.

PHP Code:

#include <sourcemod>
#include <sdktools>
#include <sdkhooks>

bool g_bPlanting[MAXPLAYERS+1] = {false, ...};

public void OnPluginStart()
{
    HookEvent("bomb_beginplant", Event_BeginPlant, EventHookMode_Pre);
    HookEvent("bomb_abortplant", Event_Abort);
    HookEvent("bomb_planted", Event_Abort);
    HookEvent("player_death", Event_Abort);
}

public void OnClientPutInServer(int client)
{
    g_bPlanting[client] = false;
    SDKHook(client, SDKHook_PreThink, PreThink);
}

public Action PreThink(int client)
{
    if(!IsPlayerAlive(client))
    {
        return;
    }
    if(!g_bPlanting[client])
    {
        return;
    }
    if(GetEntProp(client, Prop_Send, "m_bDucking") != 1)
        SetEntProp(client, Prop_Send, "m_bDucking", 1);
    if(!(GetEntityFlags(client) & FL_DUCKING))
        SetEntityFlags(client, GetEntityFlags(client)|FL_DUCKING);
}

public Action OnPlayerRunCmd(int iClient, int &iButtons, int &iImpulse, float Velocity[3], float fAngles[3], int &iWeapon)
{
    if(!IsPlayerAlive(iClient))
    {
        return Plugin_Continue;
    }
    if(!g_bPlanting[iClient])
    {
        return Plugin_Continue;
    }
    iButtons |= IN_DUCK;
    return Plugin_Changed;
} 

public Action Event_BeginPlant(Event ev, const char[] name, bool dbc)
{
    int client = GetClientOfUserId(ev.GetInt("userid"));
    
    g_bPlanting[client] = true;
}

public Action Event_Abort(Event ev, const char[] name, bool dbc)
{
    int client = GetClientOfUserId(ev.GetInt("userid"));
    
    g_bPlanting[client] = false;
    SetEntProp(client, Prop_Send, "m_bDucking", 0);
    SetEntityFlags(client, GetEntityFlags(client) & ~FL_DUCKING);
}