:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-tertiary: #adb5bd;
    --border-color: #dee2e6;
    --accent-color: #0044b3;
    --accent-hover: #003380;
    --success-color: #28a745;
    --error-color: #dc3545;
    --warning-color: #ffc107;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --shadow-hover: rgba(0, 0, 0, 0.15);
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-primary: #1a1a1a;
        --bg-secondary: #2d2d2d;
        --bg-tertiary: #3d3d3d;
        --text-primary: #e9ecef;
        --text-secondary: #adb5bd;
        --text-tertiary: #6c757d;
        --border-color: #495057;
        --accent-color: #4d9fff;
        --accent-hover: #80b8ff;
        --success-color: #48d368;
        --error-color: #f5576c;
        --warning-color: #ffd93d;
        --shadow-color: rgba(0, 0, 0, 0.3);
        --shadow-hover: rgba(0, 0, 0, 0.5);
    }
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
        sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    transition: background-color 0.3s ease, color 0.3s ease;
}

header {
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    transition: background-color 0.3s ease;
}

header h1 {
    margin: 0;
    padding: 0;
    text-align: center;
    font-size: 2rem;
    font-weight: 600;
    color: var(--text-primary);
}

main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 10px 1rem;
}

.flash {
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--accent-color);
    padding: 1rem 1.5rem;
    margin-bottom: 1.5rem;
    border-radius: 6px;
    color: var(--text-primary);
    box-shadow: 0 2px 4px var(--shadow-color);
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

form {
    background-color: var(--bg-secondary);
    padding: 2rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    box-shadow: 0 2px 8px var(--shadow-color);
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

form:hover {
    box-shadow: 0 4px 12px var(--shadow-hover);
}

label {
    display: inline-block;
    min-width: 100px;
    padding: 0.5rem;
    text-align: right;
    color: var(--text-primary);
    font-weight: 500;
}

input[type="text"],
input[type="password"],
input[type="email"] {
    width: calc(100% - 120px);
    min-width: 200px;
    padding: 0.6rem 0.8rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-size: 1rem;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

input[type="text"]:focus,
input[type="password"]:focus,
input[type="email"]:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(77, 159, 255, 0.1);
}

input[type="submit"] {
    background-color: var(--accent-color);
    color: white;
    border: none;
    padding: 0.7rem 2rem;
    border-radius: 4px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.1s ease;
}

input[type="submit"]:hover {
    background-color: var(--accent-hover);
    color: var(--bg-primary);
    transform: translateY(-1px);
}

input[type="submit"]:active {
    transform: translateY(0);
}

.row {
    margin: 1rem 0;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.command {
    width: 100%;
    margin-top: 1.5rem;
    text-align: right;
}

.login,
.register {
    max-width: 400px;
    margin: 2rem auto;
}

div.items {
    display: flex;
    flex-wrap: wrap;
    justify-content: flex-start;
    gap: 1rem;
    margin: 2rem 0;
}

div.item {
    flex: 1 1 calc(33.333% - 1rem);
    min-width: 250px;
    max-width: calc(33.333% - 1rem);
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 8px var(--shadow-color);
    transition: transform 0.3s ease, box-shadow 0.3s ease, background-color 0.3s ease;
}

div.item:hover {
    transform: translateY(-4px);
    box-shadow: 0 6px 16px var(--shadow-hover);
}

a {
    display: block;
    padding: 0.5rem;
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 600;
    font-size: 1.2rem;
    border-radius: 4px;
    transition: color 0.3s ease, background-color 0.3s ease;
}

a:hover {
    background-color: var(--accent-color);
    color: var(--bg-primary);
}

a img {
    max-height: 1.5em;
    width: auto;
    vertical-align: middle;
    margin-right: 0.5rem;
}

.item div {
    padding: 0.5rem 0;
    color: var(--text-secondary);
}

@media (max-width: 768px) {
    main {
        padding: 1rem;
    }

    header h1 {
        font-size: 1.5rem;
    }

    form {
        padding: 1.5rem;
    }

    label {
        min-width: 80px;
        font-size: 0.9rem;
    }

    input[type="text"],
    input[type="password"],
    input[type="email"] {
        width: calc(100% - 100px);
        min-width: 150px;
    }

    div.item {
        flex: 1 1 calc(50% - 1rem);
        max-width: calc(50% - 1rem);
    }
}

@media (max-width: 480px) {
    .row {
        flex-direction: column;
        align-items: stretch;
    }

    label {
        text-align: left;
        min-width: auto;
        margin-bottom: 0.3rem;
    }

    input[type="text"],
    input[type="password"],
    input[type="email"] {
        width: 100%;
        min-width: auto;
    }

    div.item {
        flex: 1 1 100%;
        max-width: 100%;
    }

    .command {
        text-align: center;
    }

    input[type="submit"] {
        width: 100%;
    }
}