*,
*::before,
*::after {
    box-sizing: border-box;
}

/* Custom properties */

:root {
    --ff-primary: 'Source Sans Pro', sans-seriff;
    --ff-secondary: 'Source Code Pro', monospace;
    
    --fw-reg: 300;
    --fw-bold: 900;
    
    --clr-light: #fff;
    --clr-dark: #303030;
    --clr-accent: #337BBD;
    
    --fs-h1: 3rem;
    --fs-h2: 2.25rem;
    --fs-h3: 1.25rem;
    --fs-body: 1rem;
    
    --bs: 0.25em 0.25em 0.75em rgba(0,0,0,.25),
          0.125em 0.125em 0.25em rgba(0,0,0,.15);
}

@media (min-width: 800px) {
    :root {
        --fs-h1: 4.5rem;
        --fs-h2: 3.75rem;
        --fs-h3: 1.5rem;
        --fs-body: 1.125rem;
    }
}

html {
    scroll-behavior: smooth;
}

body {
    background: var(--clr-light);
    color: var(--clr-dark);
    margin: 0;
    font-family: var(--ff-primary);
    font-size: var(--fs-body);
    line-height: 1.6;
}

section {
    padding: 5em 2em;
}

img {
    display: block;
    max-width: 100%;
}

strong { font-weight: var(--fw-bold); }

:focus {
    outline: 3px solid var(--clr-accent);
    outline-offset: 3px;
}

.btn {
    display: inline-block;
    padding: .5em 2.5em;
    background: var(--clr-accent);
    color: var(--clr-dark);
    text-decoration: none;
    cursor: pointer;
    font-size: .8rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    font-weight: var(--fw-bold);
    transition: transform 200ms ease-in-out;    
}

.btn:hover {
    transform: scale(1.1);
}

h1,
h2,
h3 {
    line-height: 1;
    margin: 0;
}

h1 { font-size: var(--fs-h1) }
h2 { font-size: var(--fs-h2) }
h3 { font-size: var(--fs-h3) }

.section__title {
    margin-bottom: .25em;
}

/* header */

header {
    display:flex;
    justify-content: right;
    padding: 1em;
}

nav{
    position: fixed;
    background-color: var(--clr-dark);
    color: var(--clr-light);
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 100;

    transform: translateX(100%);
    transition: transform 250ms cubic-bezier(.5, 0, .5, 1);
}

.nav__list {
    list-style: none;
    display:flex;
    height: 100%;
    flex-direction: column;
    justify-content: space-evenly;
    align-items: center;
    margin: 0;
    padding: 0;
}

.nav__link {
    color: inherit;
    font-weight: var(--fw-bold);
    font-size: var(--fs-h2);
    text-decoration: none;
}

.nav__link:hover {
    color: var(--clr-accent);
}

.nav-toggle {
    padding: .5em;
    background:transparent;
    border: 0;
    cursor: pointer;
    position: absolute;
    right: 1em;
    top: 1em;
    z-index: 1000;
}

.nav-open .nav {
    transform: translateX(0);    
}

.nav-open .nav-toggle {
    position: fixed;
}

.nav-open .hamburger {
    transform: rotate(.625turn);
}

.nav-open .hamburger::before {
    transform: rotate(90deg) translateX(-6px);
}

.nav-open .hamburger::after {
    opacity: 0;
}

.hamburger {
    display: block;
    position: relative;
}

.hamburger,
.hamburger::after,
.hamburger::before {
    background: var(--clr-accent);
    width: 2em;
    height: 3px;
    border-radius: 1em;
    transition: transform 250ms ease-in-out;
}

.hamburger::before,
.hamburger::after {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
}

.hamburger::before { top: 6px;}

.hamburger::after { bottom: 6px;}

/* Footer */
footer {
    padding: .5em 0 .5em 0;
    text-align: center;
    color: var(--clr-accent);
    background-color: black;
}

.footer__link {
    font-size: var(--fs-h3);
    font-weight: var(--fw-bold);
}

footer a {
    color: inherit;
    text-decoration: none;
}

.footer__link:hover, 
.social-list__link:hover {
    opacity: .7;
}

.footer__link:hover {
    text-decoration: underline;
}

.social-list {
    list-style: none;
    display: flex;
    justify-content:center;
    margin: 2em 0;
    padding: 0;
}

.social-list__item {
    margin: 0 .5em;
}

.social-list__link {
    padding: .5em;
}