:root {
    --bg: #ffffff;
    --text: #1d1d1f;
    --accent: #0071e3;
    --secondary: #86868b;
    --card-bg: #f5f5f7;
    --terminal-bg: #1e1e1e;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg);
    color: var(--text);
    margin: 0;
    padding: 0;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: 980px;
    margin: 0 auto;
    padding: 0 20px;
}

header {
    padding: 100px 0 60px;
    text-align: center;
}

.version-badge {
    background: var(--card-bg);
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 13px;
    font-weight: 600;
    color: var(--secondary);
    display: inline-block;
    margin-bottom: 24px;
}

h1 {
    font-size: 64px;
    font-weight: 700;
    letter-spacing: -0.015em;
    margin: 0 0 24px;
    line-height: 1.1;
}

.hero-sub {
    font-size: 24px;
    color: var(--secondary);
    max-width: 800px;
    margin: 0 auto 48px;
    font-weight: 400;
}

.cta-group {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 24px;
    flex-wrap: wrap;
}

.demo-showcase {
    max-width: 900px;
    margin: 64px auto 0;
    border-radius: 18px;
    overflow: hidden;
    border: 1px solid #d2d2d7;
    box-shadow: 0 40px 80px -30px rgba(0, 0, 0, 0.25), 0 4px 16px rgba(0, 0, 0, 0.06);
}

.demo-showcase img {
    display: block;
    width: 100%;
    height: auto;
}

.btn {
    padding: 14px 28px;
    border-radius: 24px;
    font-size: 17px;
    font-weight: 500;
    text-decoration: none;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.btn-primary {
    background-color: var(--accent);
    color: white;
}

.btn-primary:hover {
    background-color: #0077ed;
    transform: scale(1.02);
}

.btn-secondary {
    background-color: var(--card-bg);
    color: var(--text);
}

.btn-secondary:hover {
    background-color: #e8e8ed;
}

.tech-specs {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    margin: 80px 0;
}

.spec-card {
    background: var(--card-bg);
    padding: 32px;
    border-radius: 20px;
    text-align: center;
}

.spec-card h3 {
    font-size: 32px;
    margin: 0;
    color: var(--text);
    font-weight: 700;
}

.spec-card p {
    margin: 12px 0 0;
    color: var(--secondary);
    font-size: 15px;
}

.content-section {
    padding: 60px 0;
    border-top: 1px solid #d2d2d7;
}

.content-section h2 {
    font-size: 40px;
    margin-bottom: 24px;
    letter-spacing: -0.01em;
}

.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
}

.feature-item {
    margin-bottom: 32px;
}

.feature-item h4 {
    font-size: 20px;
    margin: 0 0 8px 0;
}

.feature-item p {
    color: var(--secondary);
    margin: 0;
}

.terminal-container {
    margin-top: 40px;
    text-align: left;
    background: var(--card-bg);
    padding: 32px;
    border-radius: 20px;
}

.terminal-header {
    background: #333;
    padding: 8px 16px;
    border-radius: 10px 10px 0 0;
    display: flex;
    gap: 6px;
}

.dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
}

.dot.red {
    background: #ff5f56;
}

.dot.yellow {
    background: #ffbd2e;
}

.dot.green {
    background: #27c93f;
}

.terminal-body {
    background: var(--terminal-bg);
    color: #f8f8f2;
    padding: 24px;
    border-radius: 0 0 10px 10px;
    font-family: "SFMono-Regular", Menlo, Monaco, Consolas, monospace;
    font-size: 14px;
    overflow-x: auto;
}

.code-cmd {
    color: #50fa7b;
}

.tier-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    margin-top: 40px;
}

.tier-card {
    border: 1px solid #d2d2d7;
    padding: 32px;
    border-radius: 20px;
    background: var(--bg);
}

.tier-card h3 {
    margin: 0 0 16px 0;
    color: var(--accent);
}

footer {
    border-top: 1px solid #d2d2d7;
    padding: 60px 0;
    text-align: center;
    color: var(--secondary);
    font-size: 14px;
}

.student-corner {
    margin-bottom: 32px;
    padding: 16px;
    background: #fbfbfd;
    border-radius: 12px;
    display: inline-block;
}

.student-corner a {
    color: var(--accent);
    text-decoration: none;
    font-weight: 500;
}

footer nav {
    margin-top: 20px;
}

footer nav a {
    color: var(--secondary);
    margin: 0 12px;
    text-decoration: none;
}

@media (max-width: 768px) {
    h1 {
        font-size: 40px;
    }

    .tech-specs, .grid-2, .tier-grid {
        grid-template-columns: 1fr;
    }

    .demo-showcase {
        margin-top: 40px;
        border-radius: 12px;
    }
}


.lang-switcher {
    text-align: center;
    margin-top: 20px;
}

.lang-switcher a {
    margin: 0 5px;
    padding: 5px 10px;
    text-decoration: none;
    color: var(--secondary);
    border: 1px solid var(--card-bg);
    border-radius: 12px;
    font-size: 14px;
}

.lang-switcher a:hover {
    background-color: var(--card-bg);
    color: var(--text);
}