/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Poppins', sans-serif;
    background-color: #ECF0F1;
    color: #34495E;
    line-height: 1.6;
}

/* Container */
.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 30px;
}

header h1 {
    font-size: 2rem;
    font-weight: 600;
    color: #2C3E50;
}

.subtitle {
    font-size: 1rem;
    color: #7F8C8D;
}

/* Card */
.card {
    background: white;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    padding: 20px;
}

/* Forms */
.auth-form, .setup-form, .invoice-form {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.auth-form input, .setup-form input, .setup-form textarea, .invoice-form input, .invoice-form select {
    padding: 10px;
    border: 1px solid #BDC3C7;
    border-radius: 5px;
    font-size: 1rem;
    color: #34495E;
}

.setup-form textarea {
    min-height: 80px;
    resize: vertical;
}

.invoice-form .item {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 50px;
    gap: 10px;
    align-items: center;
    margin-bottom: 10px;
}

.invoice-form .item button.remove-item {
    background: #E74C3C;
    color: white;
    border: none;
    padding: 5px;
    border-radius: 5px;
    cursor: pointer;
    transition: background 0.3s;
}

.invoice-form .item button.remove-item:hover {
    background: #C0392B;
}

/* Buttons */
button {
    background: #3498DB;
    color: white;
    padding: 12px;
    border: none;
    border-radius: 5px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.3s;
}

button:hover {
    background: #2980B9;
}

.invoice-form button#add-item {
    background: #27AE60;
    width: 150px;
    align-self: flex-start;
}

.invoice-form button#add-item:hover {
    background: #219653;
}

/* Navigation Links */
.nav-links {
    margin-top: 20px;
    text-align: center;
}

.nav-links a {
    display: inline-block;
    padding: 8px 16px;
    margin: 0 5px;
    background: #3498DB;
    color: white;
    text-decoration: none;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    transition: background 0.3s, transform 0.2s;
}

.nav-links a:hover {
    background: #2980B9;
    transform: translateY(-2px);
}

/* Messages */
.success {
    color: #27AE60;
    font-weight: 600;
    margin-bottom: 10px;
}

.error {
    color: #E74C3C;
    font-weight: 600;
    margin-bottom: 10px;
}

/* Table */
.link-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 20px;
}

.link-table th, .link-table td {
    padding: 10px;
    border: 1px solid #BDC3C7;
    text-align: left;
}

.link-table th {
    background: #2C3E50;
    color: white;
    font-weight: 600;
}

.link-table td {
    background: #FFFFFF;
}

.no-links {
    text-align: center;
    color: #7F8C8D;
}

/* Footer */
footer {
    text-align: center;
    margin-top: 30px;
    color: #7F8C8D;
    font-size: 0.9rem;
}