how do I get my mac to shrink my screen down to test media queries. The instructor is going way too fast.

/* Web Fonts -------------------- */

@font-face { font-family: 'Abolition Regular'; src: url('../fonts/abolition-regular-webfont.eot'); src: url('../fonts/abolition-regular-webfont.eot?#iefix') format('embedded-opentype'), url('../fonts/abolition-regular-webfont.woff') format('woff'), url('../fonts/abolition-regular-webfont.ttf') format('truetype'); }

/* Base Styles -------------------- */

• { box-sizing: border-box; }

body { color: #878787; margin: 0; font: 1em/1.5 "Helvetica Neue", Helvetica, Arial, sans-serif; }

h1, h2 { font-family: 'Abolition Regular', Helvetica, Arial, sans-serif; }

h1 {
font-size: 5.625rem; /* 90px/16px / color: rgba(255, 255, 255, 1); text-transform: uppercase; font-weight: normal; line-height: 1.3; text-shadow: 0 1px 0 #ccc, / 3D text shadow */ 0 2px 0 #c9c9c9, 0 3px 0 #bbb, 0 4px 0 #b9b9b9, 0 5px 0 #aaa, 0 6px 1px rgba(0,0,0,.1), 0 0 5px rgba(0,0,0,.1), 0 1px 3px rgba(0,0,0,.3), 0 3px 5px rgba(0,0,0,.2), 0 5px 10px rgba(0,0,0,.25), 0 10px 10px rgba(0,0,0,.2), 0 20px 20px rgba(0,0,0,.15); margin: 12px 0 0; }

h2 { font-size: 3.3125em; /* 53px/16px / font-weight: normal; line-height: 1.1; margin: 0 0 .5em; / 0 0 26px */ }

h3 { font-size: 1.25em; /* 20px/16px / color: #48525c; line-height: 1.2; margin-bottom: 1.7em; / 34px */ }

img { max-width: 100%; margin-bottom: 20px; border-radius: 10px; }

ul, ol { margin: 30px 0; }

li { margin-bottom: 10px; }

/* Pseudo-classes ------------------ */

a:link { color: rgb(255, 169, 73); text-decoration: none; }

a:visited { color: lightblue; }

a:hover { color: rgba(255, 169, 73, .4); }

a:active { color: lightcoral; }

/* Main Styles --------------------- */

.main-header { padding-top: 170px; height: 850px;

background: linear-gradient(#ffa949, transparent 90%), linear-gradient(0deg, #fff, transparent), #ffa949 url('../img/mountains.jpg') no-repeat center;

background-size: cover; }

.title { color: white; font-size: 1.625rem; /* 26px/16px */ letter-spacing: .065em; font-weight: 200; border-bottom: 2px solid; padding-bottom: 10px; }

.intro { font-size: 1.25em; /* 20px/16px */ line-height: 1.6;
}

.primary-content, .main-header, .main-footer { text-align: center; }

.primary-content { padding-top: 25px; padding-bottom: 95px; }

.secondary-content { padding-top: 80px; padding-bottom: 70px; border-bottom: 2px solid #dfe2e6; }

.callout { font-size: 1.25em; border-bottom: 3px solid; padding: 0 9px 3px; margin-top: 20px; display: inline-block; }

.main-footer { padding-top: 60px; padding-bottom: 60px; border-bottom: 10px solid #ffa949; }

.t-border { border-top: 2px solid #dfe2e6; }

/* Layout Styles ------------------ */

.primary-content, .secondary-content { width: 75%; padding-left: 50px; padding-right: 50px; margin: auto; max-width: 960px; }

.wildlife { color: white; text-align: left; padding: 18% 24%; border-top: 10px solid #ffa949; margin: 105px 0 60px; background: #434a52 url('../img/bear.jpg') no-repeat center; background-size: cover; box-shadow: inset 0px 0px 50px 10px rgba(0,0, 0, 1);

border-radius: 10px;

}

.arrow { width: 50px; margin-top: 150px;

}

/* Floated Columns ------------------ */

.resorts, .tips { width: 46.5%; }

.tips { float: left; }

.resorts { float: right; }

/* Float Clearfix ------------------ */

.group:after { content: ""; display: table; clear: both; }

/* Media Queries -------------------- */

@media (max-width: 1024px) { .primary-content, .secondary-content { width: 90%; }

.wildlife { padding: 10% 12%; margin: 50px 0 20px; } }

@media (max-width: 768px) { .primary-content, .secondary-content { width: 100%; padding: 20px; border: none; }

.main-header { max-height: 380px; padding: 50px 25px 0; }

.title { font-size: 1.3rem; border: none; }

h1 { font-size: 5rem; line-height: 1.1; }

.arrow { display: none; }

.intro font-size: 1rem; }

.resorts, .tips { float: none; width: 100%; }

/* @media (max-width: 960px) { body { background: royalblue; } }

@media (max-width: 480px) { body { background: darkred; } }

@media (min-width: 481px) and (max-width: 700px) { body { background: seagreen; } p { color: white; } }

*/

I use Chrome dev tools, so on Google Chrome press cmd+alt+i and it has a device mode in the top left of the panel window. You can choose presets or set your own massive screen size or just drag it around. It also emulates touch screen swiping.