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

:root {
    --background: #f5f6f8;
    --card-background: #ffffff;
    --text: #17181a;
    --secondary-text: #6b7280;
    --border: #e5e7eb;
    --card-hover: #f9fafb;
    --shadow: rgba(0, 0, 0, 0.06);
}

body.dark {
    --background: #111315;
    --card-background: #191c20;
    --text: #f3f4f6;
    --secondary-text: #9ca3af;
    --border: #292d33;
    --card-hover: #1e2227;
    --shadow: rgba(0, 0, 0, 0.25);
}

body {
    font-family: Arial, Helvetica, sans-serif;
    background: var(--background);
    color: var(--text);
    min-height: 100vh;

    transition:
        background-color 0.25s ease,
        color 0.25s ease;
}


/* Header */

.header {
    border-bottom: 1px solid var(--border);
    background: var(--card-background);
}

.header-content {
    max-width: 1100px;
    margin: auto;
    padding: 28px 24px;

    display: flex;
    align-items: center;
    justify-content: space-between;
}

.header h1 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 6px;
}

.header p {
    color: var(--secondary-text);
    font-size: 15px;
}


/* Theme button */

.theme-toggle {
    width: 42px;
    height: 42px;

    border: 1px solid var(--border);
    border-radius: 10px;

    background: var(--card-background);
    color: var(--text);

    cursor: pointer;
    font-size: 17px;

    transition: 0.2s ease;
}

.theme-toggle:hover {
    background: var(--card-hover);
}


/* Main */

.container {
    max-width: 1100px;
    margin: auto;
    padding: 40px 24px;
}


/* Projects */

.projects-grid {
    display: grid;

    grid-template-columns: repeat(3, 1fr);

    gap: 20px;
}


/* Project card */

.project-card {
    display: flex;
    flex-direction: column;

    min-height: 190px;

    padding: 24px;

    background: var(--card-background);

    border: 1px solid var(--border);
    border-radius: 14px;

    text-decoration: none;
    color: var(--text);

    box-shadow: 0 4px 15px var(--shadow);

    transition:
        transform 0.2s ease,
        box-shadow 0.2s ease,
        background-color 0.2s ease;
}

.project-card:hover {
    transform: translateY(-4px);

    background: var(--card-hover);

    box-shadow: 0 10px 25px var(--shadow);
}

.project-card h2 {
    font-size: 19px;
    font-weight: 600;

    margin-bottom: 12px;
}

.project-card p {
    color: var(--secondary-text);

    font-size: 14px;
    line-height: 1.6;
}


/* Footer */

.footer {
    max-width: 1100px;
    margin: auto;

    padding: 20px 24px 30px;

    color: var(--secondary-text);

    font-size: 13px;
}


/* Tablet */

@media (max-width: 850px) {
    .projects-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}


/* Mobile */

@media (max-width: 550px) {
    .header-content {
        padding: 22px 18px;
    }

    .header h1 {
        font-size: 24px;
    }

    .container {
        padding: 28px 18px;
    }

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

    .project-card {
        min-height: 160px;
    }
}