:root {
    /* Material Design 3 Tokens - Dark Theme */
    --md-sys-color-background: #121212;
    --md-sys-color-surface: #1e1e1e;
    --md-sys-color-surface-container: #232325;
    --md-sys-color-surface-container-high: #2c2c2e;

    --md-sys-color-primary: #a8c7fa;
    --md-sys-color-on-primary: #002f69;
    --md-sys-color-primary-container: #004692;
    --md-sys-color-on-primary-container: #d6e2ff;

    --md-sys-color-secondary: #c2e7ff;
    --md-sys-color-on-secondary: #001d35;

    --md-sys-color-outline: #8e9099;
    --md-sys-color-outline-variant: #44474f;

    --md-sys-color-on-surface: #e2e2e6;
    --md-sys-color-on-surface-variant: #c4c6d0;

    /* Typography */
    --md-sys-typescale-display-large: 57px;
    --md-sys-typescale-display-medium: 45px;
    --md-sys-typescale-headline-small: 24px;
    --md-sys-typescale-body-large: 16px;

    /* Shapes */
    --md-sys-shape-corner-large: 28px;
    --md-sys-shape-corner-full: 9999px;

    /* Elevation */
    --md-sys-elevation-level1: 0 1px 3px 0 rgba(0, 0, 0, 0.3), 0 4px 8px 3px rgba(0, 0, 0, 0.15);
    --md-sys-elevation-level2: 0 4px 8px 3px rgba(0, 0, 0, 0.35), 0 6px 14px 4px rgba(0, 0, 0, 0.20);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background-color: var(--md-sys-color-background);
    color: var(--md-sys-color-on-surface);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.container {
    width: 100%;
    max-width: 900px;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 4rem;
}

/* Header / Hero */
header {
    text-align: center;
    margin-top: 4rem;
    animation: fadeIn 0.8s ease-out;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 2rem;
    padding: 12px 24px;
    background: var(--md-sys-color-surface-container);
    border-radius: var(--md-sys-shape-corner-full);
}

.logo-icon {
    font-size: 24px;
}

h1 {
    font-size: 20px;
    font-weight: 500;
    color: var(--md-sys-color-on-surface);
    letter-spacing: 0.5px;
}

.headline {
    font-size: var(--md-sys-typescale-display-medium);
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1.5rem;
    background: linear-gradient(180deg, #fff 0%, #b0b0b0 100%);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.subhead {
    font-size: 18px;
    color: var(--md-sys-color-on-surface-variant);
    max-width: 600px;
    margin: 0 auto;
}

/* Download FAB */
.download-area {
    display: flex;
    justify-content: center;
    margin-top: 3rem;
}

.fab-extended {
    display: inline-flex;
    align-items: center;
    gap: 16px;
    height: 64px;
    padding: 0 32px;
    background-color: var(--md-sys-color-primary);
    color: var(--md-sys-color-on-primary);
    border-radius: 20px;
    /* MD3 uses 16-20px for FABs */
    text-decoration: none;
    font-size: 16px;
    font-weight: 600;
    transition: all 0.3s cubic-bezier(0.2, 0, 0, 1);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.fab-extended:hover {
    background-color: #bfd8ff;
    /* slightly lighter on hover */
    transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.3);
}

.fab-icon {
    font-size: 24px;
}

.meta-info {
    margin-top: 1rem;
    font-size: 14px;
    color: var(--md-sys-color-outline);
    text-align: center;
    display: flex;
    gap: 12px;
    justify-content: center;
}

/* Cards */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.card {
    background-color: var(--md-sys-color-surface-container);
    padding: 32px;
    border-radius: var(--md-sys-shape-corner-large);
    transition: background-color 0.2s;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.card:hover {
    background-color: var(--md-sys-color-surface-container-high);
}

.icon-box {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--md-sys-color-surface);
    border-radius: 16px;
    font-size: 20px;
    color: var(--md-sys-color-primary);
}

.card h3 {
    font-size: 20px;
    font-weight: 600;
    color: var(--md-sys-color-on-surface);
}

.card p {
    color: var(--md-sys-color-on-surface-variant);
    font-size: 15px;
    line-height: 1.6;
}

/* Usage Steps */
.usage-section {
    background-color: var(--md-sys-color-surface-container);
    border-radius: var(--md-sys-shape-corner-large);
    padding: 40px;
}

.usage-section h2 {
    font-size: 24px;
    margin-bottom: 32px;
    text-align: center;
}

.step-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.step {
    display: flex;
    align-items: center;
    gap: 20px;
    padding: 16px;
    background: var(--md-sys-color-surface);
    border-radius: 16px;
}

.step-number {
    width: 32px;
    height: 32px;
    background: var(--md-sys-color-secondary);
    color: var(--md-sys-color-on-secondary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 14px;
}

kbd {
    background: var(--md-sys-color-surface-container-high);
    border: 1px solid var(--md-sys-color-outline-variant);
    border-radius: 8px;
    padding: 4px 8px;
    font-family: inherit;
    font-size: 0.9em;
    color: var(--md-sys-color-on-surface);
}

footer {
    text-align: center;
    padding-bottom: 3rem;
    color: var(--md-sys-color-outline);
    font-size: 14px;
}

footer a {
    color: var(--md-sys-color-primary);
    text-decoration: none;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 600px) {
    .headline {
        font-size: 32px;
    }

    .grid {
        grid-template-columns: 1fr;
    }
}