error code CS0266 (can't convert type 'double' to 'float')

I’m creating a movement script for my game and I keep getting this error, does anybody know how to fix this? (it’s on lines 10,28)

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerMovement : MonoBehaviour
{
    public CharacterController controller;

    public float speed = 12f;
    public float gravity = -9.81;

    Vector3 velocity;

    void Update()
    {
        float x = Input.GetAxis("Horizontal");
        float z = Input.GetAxis("Vertical");

        Vector3 move = transform.right * x + transform.forward * z;

        if (move.magnitude > 1)
            move /= move.magnitude;

        controller.Move(move * speed * Time.deltaTime);

        velocity.y += gravity * Time.deltaTime;

        controller.Move(velocity * Time.deltaTime);
    }
}

public float gravity = -9.81f;
just a small oversight with the float value needing an ‘f’ at the end