/* ==========================================================
   StudyLedgerOS
   style.css
========================================================== */

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

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    background: #ffffff;
    color: #111111;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
    font-size: 18px;
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

img,
video {
    display: block;
    width: 100%;
    border-radius: 18px;
    border: 1px solid #e8e8e8;
    box-shadow: 0 20px 50px rgba(0, 0, 0, .08);
}

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

section {
    max-width: 1200px;
    margin: 0 auto;
    padding: 110px 32px;
}

section + section {
    border-top: 1px solid #f0f0f0;
}

/* ==========================================================
   Header
========================================================== */

header {
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 40px;
    background: rgba(255,255,255,.96);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid #ececec;
}

.logo {
    font-size: 28px;
    font-weight: 600;
    letter-spacing: -.03em;
}

nav {
    display: flex;
    gap: 30px;
}

nav a {
    font-size: 15px;
    color: #666;
    transition: .25s;
}

nav a:hover {
    color: #000;
}

/* ==========================================================
   Hero
========================================================== */

.hero {
    min-height: 85vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    border: none;
}

.hero-content {
    max-width: 900px;
}

.hero h1 {
    margin: 0;
    font-size: clamp(64px, 9vw, 92px);
    font-weight: 650;
    letter-spacing: -.05em;
}

.hero h2 {
    margin: 30px auto;
    max-width: 850px;
    font-size: clamp(28px, 4vw, 42px);
    font-weight: 300;
    color: #333;
}

.hero p {
    max-width: 760px;
    margin: 0 auto;
    font-size: 22px;
    color: #666;
}

.hero-buttons {
    margin: 50px 0;
}

.button-primary {
    display: inline-block;
    padding: 18px 34px;
    border-radius: 999px;
    background: #111;
    color: #fff;
    font-weight: 600;
    transition: .25s;
}

.button-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 28px rgba(0,0,0,.18);
}

.hero-note {
    margin-top: 40px;
    color: #888;
    font-size: 16px;
}

/* ==========================================================
   Typography
========================================================== */

h2 {
    margin: 0 0 24px;
    font-size: clamp(42px, 5vw, 60px);
    letter-spacing: -.04em;
    line-height: 1.05;
}

h3 {
    margin-top: 0;
    margin-bottom: 14px;
    font-size: 28px;
    letter-spacing: -.02em;
}

.section-intro,
.section-footer,
section > p {
    max-width: 780px;
    color: #555;
}

/* ==========================================================
   Cards
========================================================== */

.feature-grid,
.metrics,
.applications {
    display: grid;
    gap: 28px;
    margin: 50px 0;
}

/* Learn + Customize */

.feature-grid {
    grid-template-columns: repeat(4, 1fr);
}

/* Measure */

.metrics {
    grid-template-columns: repeat(4, 1fr);
}

/* Applications */

.applications {
    grid-template-columns: repeat(5, 1fr);
}

.feature-grid article,
.metrics div,
.applications article {
    background: #fff;
    border: 1px solid #ececec;
    border-radius: 18px;
    padding: 34px;
    text-align: center;
    box-shadow: 0 10px 30px rgba(0,0,0,.05);
    transition: .25s;
}

.feature-grid article:hover,
.metrics div:hover,
.applications article:hover {
    transform: translateY(-4px);
    box-shadow: 0 20px 50px rgba(0,0,0,.08);

/* ==========================================================
   Demo
========================================================== */

#demo video {
    margin-top: 40px;
}

/* ==========================================================
   Images
========================================================== */

#review img,
#measure img,
#plan img,
#analyze img {
    margin-top: 40px;
}

/* ==========================================================
   FAQ
========================================================== */

#faq h3 {
    margin-top: 48px;
}

#faq p {
    color: #666;
}

/* ==========================================================
   Footer
========================================================== */

footer {
    margin-top: 80px;
    padding: 60px 30px;
    border-top: 1px solid #ececec;
    text-align: center;
    color: #888;
}

footer p {
    margin: 10px 0;
}

/* ==========================================================
   Tablet
========================================================== */

@media (max-width: 1000px) {

    .feature-grid,
    .metrics {
        grid-template-columns: repeat(2, 1fr);
    }

    .applications {
        grid-template-columns: repeat(3, 1fr);
    }

}

/* ==========================================================
   Mobile
========================================================== */

@media (max-width: 700px) {

    header {
        flex-direction: column;
        gap: 20px;
        padding: 20px;
    }

    nav {
        flex-wrap: wrap;
        justify-content: center;
        gap: 18px;
    }

    section {
        padding: 80px 24px;
    }

    .hero {
        min-height: auto;
        padding-top: 80px;
    }

    .hero h1 {
        font-size: 56px;
    }

    .hero h2 {
        font-size: 30px;
    }

    .hero p {
        font-size: 20px;
    }

    .review-flow {
        font-size: 22px;
    }

    .feature-grid,
    .metrics,
    .applications {
        grid-template-columns: 1fr;
    }

}