:root {
    --celadon: #AFE1AF;
    --celadon-dark: #6b9b6b;
    --bg: #f8faf9;
    --surface: #ffffff;
    --text: #24303f;
    --muted: #6e7d8b;
    --border: #e7ecf0;
    --shadow: 0 18px 40px rgba(35, 53, 72, 0.08);
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    min-height: 100vh;
    background: linear-gradient(180deg, #fdfdfd 0%, #f2f6f9 100%);
    color: var(--text);
    font-family: 'Lora', serif;
    line-height: 1.6;
}

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

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

.top-nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 100;
    padding: 1rem 0;
    background: rgba(255, 255, 255, 0.95);
    border-bottom: 1px solid rgba(154, 168, 178, 0.16);
    backdrop-filter: blur(10px);
}

.nav-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

.logo {
    font-family: 'Playfair Display', serif;
    font-size: 1.5rem;
    font-weight: 900;
}

.logo span {
    color: var(--celadon-dark);
}

.top-nav ul {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 1.25rem;
    margin: 0;
    padding: 0;
}

.top-nav a {
    font-size: 0.9rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text);
}

.top-nav a:hover,
.top-nav a:focus-visible {
    color: var(--celadon-dark);
}

.container {
    max-width: 1080px;
    margin: 0 auto;
    padding: 120px 1.5rem 3rem;
}

h1 {
    margin: 0 0 1.5rem;
    text-align: center;
    font-family: 'Playfair Display', serif;
    font-size: clamp(2.5rem, 4vw, 3.75rem);
    letter-spacing: -0.04em;
    color: var(--text);
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
    padding: 0;
    margin: 0;
    list-style: none;
}

.course-grid li {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 18px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}

.course-grid li:hover,
.course-grid li:focus-within {
    transform: translateY(-4px);
    border-color: var(--celadon);
    box-shadow: 0 24px 52px rgba(35, 53, 72, 0.12);
}

.course-grid a {
    display: block;
    height: 100%;
}

.course-grid img {
    width: 100%;
    height: auto;
    object-fit: cover;
    display: block;
    background: #f4f7fa;
    border-bottom: 1px solid var(--border);
}

@media (max-width: 720px) {
    .nav-container {
        flex-direction: column;
        align-items: flex-start;
    }

    .top-nav ul {
        gap: 0.75rem;
    }

    .container {
        padding-top: 140px;
    }
}

@media (max-width: 520px) {
    .course-grid {
        grid-template-columns: 1fr;
    }

    .top-nav {
        padding-bottom: 0.75rem;
    }
}