:root {
    --primary-color: #4CAF50;
    --secondary-color: #333;
    --text-color: #333;
    --bg-color: #f4f4f4;
    --white: #fff;
    --shadow: 0 2px 5px rgba(0,0,0,0.1);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    background-color: var(--bg-color);
    color: var(--text-color);
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navbar */
.navbar {
    background-color: var(--white);
    box-shadow: var(--shadow);
    padding: 1rem 0;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
}

.nav-links {
    list-style: none;
    display: flex;
}

.nav-links li {
    margin-left: 20px;
}

.nav-links a {
    text-decoration: none;
    color: var(--secondary-color);
    font-weight: 500;
}

.nav-links a:hover, .nav-links a.active {
    color: var(--primary-color);
}

/* Main Content */
main {
    padding: 2rem 0;
    min-height: calc(100vh - 140px);
}

/* Hero Section */
.hero {
    text-align: center;
    padding: 3rem 0;
    background: var(--white);
    border-radius: 10px;
    margin-bottom: 2rem;
    box-shadow: var(--shadow);
}

.hero h1 {
    margin-bottom: 1rem;
    font-size: 2.5rem;
}

/* Features */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}

.feature-card {
    background: var(--white);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
    text-align: center;
}

.feature-card h3 {
    margin-bottom: 1rem;
}

.feature-card p {
    margin-bottom: 1.5rem;
}

/* Buttons */
.btn {
    display: inline-block;
    background: var(--primary-color);
    color: var(--white);
    padding: 0.5rem 1.5rem;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    text-decoration: none;
    font-size: 1rem;
    transition: background 0.3s;
}

.btn:hover {
    background: #45a049;
}

.btn:disabled {
    background: #ccc;
    cursor: not-allowed;
}

.btn-small {
    padding: 0.3rem 1rem;
    font-size: 0.9rem;
}

/* Forms */
.login-container {
    max-width: 400px;
    margin: 2rem auto;
    background: var(--white);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
}

.login-container h2 {
    text-align: center;
    margin-bottom: 1.5rem;
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
}

.form-group input {
    width: 100%;
    padding: 0.8rem;
    border: 1px solid #ddd;
    border-radius: 5px;
}

/* Messages */
.message {
    padding: 10px;
    margin-top: 10px;
    border-radius: 5px;
    display: none;
    text-align: center;
}

.message.success {
    background-color: #d4edda;
    color: #155724;
}

.message.error {
    background-color: #f8d7da;
    color: #721c24;
}

/* Files List */
.files-list {
    margin-top: 2rem;
}

.file-item {
    background: var(--white);
    padding: 1rem;
    margin-bottom: 1rem;
    border-radius: 5px;
    box-shadow: var(--shadow);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* Footer */
footer {
    background: var(--secondary-color);
    color: var(--white);
    text-align: center;
    padding: 1rem 0;
    margin-top: auto;
}