/* Reset defaults */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
html,
body {
    height: 100%;
    font-family: sans-serif;
}
/* Flex layout for sticky footer */
body {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}
/* Default: light mode */
body {
    background-color: #ffffff;
    color: #1a1a1a;
}
header {
    position: sticky;
    top: 0;
    left: 0;
    width: 100%;
    background-color: #f5f5f5;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 1000;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

header h1 a {
    color: inherit;
    text-decoration: none;
    transition: opacity 0.2s;
}

header h1 a:hover {
    opacity: 0.7;
}
header h1 {
    font-size: 1.5rem;
    color: #1a1a1a;
}
header nav {
    display: flex;
    gap: 1.5rem;
}
header nav a {
    color: #4a4a4a;
    text-decoration: none;
    position: relative;
    transition:
        color 0.2s,
        opacity 0.2s;
    padding: 0.5rem 0;
    opacity: 0.7;
}
header nav a:hover {
    opacity: 0.85;
}
header nav a.active {
    color: #1a1a1a;
    opacity: 1;
    font-weight: 600;
}

/* Hamburger menu button - hidden by default */
.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.menu-toggle span {
    width: 25px;
    height: 3px;
    background-color: #1a1a1a;
    transition: all 0.3s ease;
}

main {
    flex: 1;
    padding: 2rem;
}
footer {
    background-color: #f5f5f5;
    text-align: center;
    padding: 1rem 0;
    color: #6a6a6a;
    border-top: 1px solid #e0e0e0;
}

footer a {
    display: inline-block;
    margin-left: 1rem;
    color: #6a6a6a;
    transition:
        color 0.2s,
        opacity 0.2s;
    vertical-align: middle;
}

footer a:hover {
    opacity: 0.7;
}

footer a svg {
    display: block;
}

/* Responsive nav with hamburger */
@media (max-width: 600px) {
    .menu-toggle {
        display: flex;
    }

    header nav {
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background-color: #f5f5f5;
        flex-direction: column;
        gap: 0;
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s ease;
        box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    }

    header nav.active {
        max-height: 300px;
    }

    header nav a {
        display: block;
        width: 100%;
        padding: 1rem 2rem;
        border-bottom: 1px solid #e0e0e0;
    }

    header nav a:last-child {
        border-bottom: none;
    }

    /* Hamburger animation */
    .menu-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .menu-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .menu-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }

    main {
        padding: 1rem;
    }
}

/* Dark mode overrides */
@media (prefers-color-scheme: dark) {
    body {
        background-color: #1a1a1a;
        color: #e5e5e5;
    }
    header {
        background-color: #0a0a0a;
        box-shadow: 0 1px 3px rgba(255, 255, 255, 0.05);
    }
    header h1 {
        color: #e5e5e5;
    }
    header nav a {
        color: #a0a0a0;
        opacity: 0.7;
    }
    header nav a:hover {
        opacity: 0.85;
    }
    header nav a.active {
        color: #e5e5e5;
        opacity: 1;
    }
    footer {
        background-color: #0a0a0a;
        color: #6a6a6a;
        border-top: 1px solid #2a2a2a;
    }

    footer a {
        display: inline-block;
        margin-left: 0.5rem;
        color: #6a6a6a;
        transition: opacity 0.2s;
        vertical-align: middle;
    }

    footer a:hover {
        opacity: 0.7;
    }

    footer a svg {
        display: block;
    }
    .menu-toggle span {
        background-color: #e5e5e5;
    }

    @media (max-width: 600px) {
        header nav {
            background-color: #0a0a0a;
        }

        header nav a {
            border-bottom: 1px solid #2a2a2a;
        }
    }
}