:root {
    /* color palette */
    --color-primary: #667eea;
    --color-primary-dark: #5a67d8;
    --color-secondary: #764ba2;
    --color-accent: #f5576c;
    --color-bg: #f5f5f5;
    --color-bg-alt: #ffffff;
    --color-text: #333;
    --color-link: var(--color-primary);

    /* typography */
    --font-base: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-heading: 'Segoe UI', Arial, sans-serif;

    /* misc */
    --radius: 8px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: var(--font-base);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
}

/* Header & Navigation */
header {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    padding: 1.5rem 0;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
}

header nav ul {
    list-style: none;
    display: flex;
    gap: 2.5rem;
    padding: 0 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

header nav ul li a {
    text-decoration: none;
    color: white;
    font-weight: 600;
    font-size: 1.05rem;
    transition: var(--transition);
    padding: 0.5rem 1rem;
    border-radius: var(--radius);
}

header nav ul li a:hover {
    background-color: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

/* Main Content */
main, .content {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 2rem;
}

h1 {
    font-size: 2.5rem;
    font-weight: bold;
    margin-bottom: 1.5rem;
    color: var(--color-primary);
    font-family: var(--font-heading);
}

h2 {
    font-size: 1.8rem;
    color: var(--color-primary);
    margin-top: 1.5rem;
    margin-bottom: 1rem;
    font-family: var(--font-heading);
}

/* Forms */
form {
    background: var(--color-bg-alt);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: 0 2px 15px rgba(0,0,0,0.08);
    max-width: 600px;
    margin: 2rem 0;
}

label {
    display: block;
    margin-bottom: 1rem;
    font-weight: 500;
    color: #333;
}

input[type="text"],
input[type="email"],
input[type="password"],
textarea {
    width: 100%;
    padding: 0.75rem;
    margin-top: 0.5rem;
    border: 2px solid #e0e0e0;
    border-radius: 6px;
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.3s, box-shadow 0.3s;
}

input[type="text"]:focus,
input[type="email"]:focus,
input[type="password"]:focus,
textarea:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

textarea {
    resize: vertical;
    min-height: 120px;
}

/* Buttons */
button, .btn {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius);
    transition: var(--transition);
    display: inline-block;
    text-decoration: none;
    margin-right: 1rem;
    margin-bottom: 1rem;
}

button:hover, .btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

button:active, .btn:active {
    transform: translateY(0);
}

button.btn-secondary {
    background: linear-gradient(135deg, #f093fb 0%, var(--color-accent) 100%);
}

button.btn-secondary:hover {
    box-shadow: 0 5px 15px rgba(245, 87, 108, 0.4);
}

/* Search Form */
form input[type="text"] {
    max-width: 300px;
    display: inline-block;
    width: auto;
}

/* Lists */
ul {
    list-style: none;
}

ul li {
    margin-bottom: 1rem;
    padding: 1.5rem;
    border-radius: var(--radius);
    box-shadow: 0 2px 10px rgba(0,0,0,0.08);
    transition: var(--transition);
    border-left: 4px solid var(--color-primary);
    background: var(--color-bg-alt);
}

ul li:hover {
    transform: translateX(5px);
    box-shadow: 0 5px 20px rgba(0,0,0,0.12);
}

ul li a {
    color: #667eea;
    text-decoration: none;
    font-weight: 600;
    font-size: 1.1rem;
    transition: color 0.3s;
}

ul li a:hover {
    color: #764ba2;
}

/* Utility and helpers */
.card,
ul li,
.article-preview {
    background: var(--color-bg-alt);
    border-radius: var(--radius);
    box-shadow: 0 2px 10px rgba(0,0,0,0.08);
    transition: var(--transition);
}

.card:hover,
ul li:hover,
.article-preview:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 20px rgba(0,0,0,0.12);
}

/* Error Messages */
p {
    margin: 1rem 0;
}

p[style*="color: red"],
.error {
    color: var(--color-accent);
    background: #ffe5e8;
    padding: 0.75rem;
    border-radius: var(--radius);
    margin: 1rem 0;
    border-left: 4px solid var(--color-accent);
}

/* responsive tweaks */
@media (max-width: 768px) {
    header nav ul {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
    }
    form,
    .card,
    ul li {
        padding: 1rem;
    }
}


/* Footer */
footer {
    background: #333;
    color: white;
    text-align: center;
    padding: 2rem;
    margin-top: 3rem;
}

/* Responsive */
@media (max-width: 768px) {
    header nav ul {
        flex-direction: column;
        gap: 1rem;
        padding: 0 1rem;
    }
    
    main, .content {
        padding: 0 1rem;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    form {
        padding: 1.5rem;
        max-width: 100%;
    }
}