:root {
    --accent-red: #bb353c;
    --accent-blue: #3b74e3;
    --accent-blue-dark: #2b52a2;
    --bg-light: #f5f5f5;
}

* {
    box-sizing: border-box;
}

html, body {
    margin: 0;
    padding: 0;
}

body {
    font-family: Arial, sans-serif;
    color: #222;
    line-height: 1.5;
    background: #fff;
    padding-bottom: 40px;
}

a {
    color: var(--accent-blue);
}

h1, h2, h3 {
    font-family: Arial, sans-serif;
    line-height: 1.1;
    font-weight: 400;
}

.container {
    margin: 0 auto;
    padding: 0 20px;
    max-width: 1200px;
}

@media (min-width: 1500px) {
    .container {
        max-width: 1400px;
    }
}

/* Header */

.site-header {
    height: 80px;
    display: flex;
    align-items: center;
    padding: 0 20px;
    position: sticky;
    top: 0;
    background: #fff;
    z-index: 10;
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.05);
}

.logo {
    height: 60px;
    line-height: 60px;
    font-size: 32px;
    text-transform: uppercase;
    font-family: monospace;
    font-weight: bolder;
    white-space: nowrap;
}

.logo span {
    color: var(--accent-red);
}

.site-nav {
    flex-grow: 1;
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: 10px;
}

.site-nav ul {
    list-style: none;
    display: flex;
    margin: 0;
    padding: 0;
}

.site-nav li a {
    font-weight: bolder;
    font-size: 16px;
    text-decoration: none;
    padding: 5px 15px;
    color: #000;
}

.site-nav li a:hover {
    color: var(--accent-blue);
}

.site-nav li a.active {
    color: var(--accent-blue);
    border-bottom: 2px solid var(--accent-blue);
}

.demo-btn {
    padding: 8px 20px;
    background: var(--accent-blue);
    border-radius: 8px;
    font-weight: bolder;
    color: #fff !important;
    text-decoration: none;
    margin-left: 10px;
    white-space: nowrap;
}

.demo-btn:hover {
    background: var(--accent-blue-dark);
}

/* Hero */

.hero {
    margin: 40px 0 30px;
    min-height: 360px;
    width: 100%;
    background: #111 url('../images/hero-bg.webp') center center / cover no-repeat;
    display: flex;
    align-items: center;
}

.hero-text {
    font-size: 56px;
    line-height: 1.1;
    font-weight: 400;
    color: var(--accent-blue);
    padding: 40px;
    max-width: 700px;
}

/* Sections */

.section {
    padding: 60px 0;
}

.section:nth-of-type(even),
.section.section-alt {
    background: var(--bg-light);
}

.section h2 {
    font-size: 30px;
    margin-top: 40px;
}

.section h2.section-title {
    font-size: 44px;
    margin-top: 0;
}

.section img {
    max-width: 100%;
    display: block;
    margin: 16px 0;
}

/* About pluses */

.about-pluses {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin: 40px 0;
    text-align: center;
}

.about-pluses div {
    flex: 1 1 18%;
    font-size: 22px;
    line-height: 1.3;
}

.about-pluses span {
    box-sizing: border-box;
    border: 3px solid var(--accent-red);
    color: #000;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    border-radius: 50%;
    width: 80px;
    height: 80px;
    font-size: 40px;
}

/* Stack list */

.stack-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
    margin-top: 20px;
}

.stack-grid h3 {
    font-size: 20px;
    margin: 0 0 10px;
}

.stack-grid ul {
    padding-left: 18px;
    margin: 0;
}

.stack-grid li {
    margin-bottom: 14px;
}

/* Contacts */

.contacts-block p {
    margin: 0 0 20px;
}

/* Footer */

.site-footer {
    background: var(--bg-light);
    padding: 15px 20px;
    text-align: center;
    font-size: 14px;
    margin-top: 40px;
}

/* Responsive */

@media (max-width: 900px) {
    .stack-grid {
        grid-template-columns: 1fr;
    }

    .about-pluses div {
        flex: 1 1 45%;
    }

    .hero-text {
        font-size: 36px;
    }
}

@media (max-width: 700px) {
    .site-header {
        flex-wrap: wrap;
        height: auto;
        padding: 15px 20px;
    }

    .site-nav {
        flex: 1 1 100%;
        flex-wrap: wrap;
        justify-content: center;
        margin-top: 10px;
    }

    .site-nav ul {
        flex-wrap: wrap;
        justify-content: center;
    }

    .section h2.section-title {
        font-size: 32px;
    }

    .hero {
        min-height: 240px;
    }

    .hero-text {
        font-size: 26px;
        padding: 20px;
    }
}