:root {
    --bg-color: #f9f9f9;
    --container-bg: #ffffff;
    --text-color: #222222;
    --nav-bg: #333333;
    --nav-text: #ffffff;
    --shadow-color: rgba(0,0,0,0.05);
    --form-border-color: #ccc;
    --alert-success-bg: #d4edda;
    --alert-success-text: #155724;
    --alert-success-border: #c3e6cb;
    --alert-danger-bg: #f8d7da;
    --alert-danger-text: #721c24;
    --alert-danger-border: #f5c6cb;
}

body.dark-mode {
    --bg-color: #1a1a1a;
    --container-bg: #2b2b2b;
    --text-color: #f0f0f0;
    --nav-bg: #222222;
    --nav-text: #f0f0f0;
    --shadow-color: rgba(0,0,0,0.2);
    --form-border-color: #555;
    --alert-success-bg: #1a4b25;
    --alert-success-text: #c3e6cb;
    --alert-success-border: #2a6836;
    --alert-danger-bg: #5a2126;
    --alert-danger-text: #f5c6cb;
    --alert-danger-border: #8a2a33;
}

nav {
    background-color: var(--nav-bg);
    color: var(--nav-text);
    display: flex;
    justify-content: space-between;
    align-items: center;

    max-width: 1100px;
    margin: 20px auto 30px auto;
    padding: 15px 25px;
    border-radius: 8px;
    box-sizing: border-box;
}

.logo {
    font-size: 1.4em;
    font-weight: 600;
    display: flex;
    align-items: center;
}
.logo i {
    margin-right: 10px;
    font-size: 1.1em;
}

.nav-left,
.nav-right {
    display: flex;
    align-items: center;
}

.nav-left > a {
    margin-right: 15px;
}

.nav-right > * {
    margin-left: 15px;
}

nav a {
    color: var(--nav-text);
    text-decoration: none;
}

nav a:hover {
    text-decoration: underline;
}

.nav-welcome {
    display: flex;
    align-items: center;
    font-size: 0.9em;
    opacity: 0.8;
}

.nav-avatar {
    width: 30px;
    height: 30px;
    border-radius: 50%;
    object-fit: cover;
    margin-right: 10px;
    background-color: var(--form-border-color);
}

.nav-button {
    padding: 5px 12px;
    border: 1px solid var(--nav-text);
    border-radius: 4px;
    transition: all 0.2s ease;
}

.nav-button:hover {
    background-color: var(--nav-text);
    color: var(--nav-bg);
    text-decoration: none;
}

.theme-button {
    background: transparent;
    border: none;
    color: var(--nav-text);
    font-size: 1.2em;
    cursor: pointer;
    padding: 0 5px;
    line-height: 1;
}