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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: #f7fafc;
    color: #2d3748;
    min-height: 100vh;
}

/* Login Screen Background */
#login-screen {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.screen {
    display: none;
}

.screen.active {
    display: block;
}

/* Login */
.login-container {
    max-width: 440px;
    width: 100%;
    margin: 0 20px;
    padding: 50px 40px;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
}

.login-container h1 {
    margin-bottom: 10px;
    text-align: center;
    color: #1a202c;
    font-size: 28px;
    font-weight: 700;
}

.login-container p {
    text-align: center;
    color: #718096;
    margin-bottom: 35px;
    font-size: 14px;
}

.login-container input {
    width: 100%;
    padding: 14px 18px;
    margin-bottom: 18px;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    font-size: 15px;
    transition: all 0.3s;
    background: #f7fafc;
}

.login-container input:focus {
    outline: none;
    border-color: #667eea;
    background: white;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.login-container button {
    width: 100%;
    padding: 14px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    margin-top: 10px;
}

.login-container button:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(102, 126, 234, 0.4);
}

.error {
    color: #e74c3c;
    font-size: 14px;
    margin-top: 10px;
    text-align: center;
}

/* Main Layout */
#main-screen {
    display: flex;
    height: 100vh;
    background: #f7fafc;
}

.sidebar {
    width: 280px;
    background: linear-gradient(180deg, #1a202c 0%, #2d3748 100%);
    color: white;
    padding: 0;
    box-shadow: 4px 0 20px rgba(0,0,0,0.1);
}

.logo {
    padding: 30px 25px;
    font-size: 22px;
    font-weight: 700;
    background: rgba(255,255,255,0.05);
    border-bottom: 1px solid rgba(255,255,255,0.1);
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo::before {
    content: "📊";
    font-size: 28px;
}

.menu {
    list-style: none;
    padding: 20px 0;
}

.menu li a {
    display: flex;
    align-items: center;
    padding: 16px 25px;
    color: #cbd5e0;
    text-decoration: none;
    transition: all 0.3s;
    font-size: 15px;
    font-weight: 500;
    border-left: 3px solid transparent;
}

.menu li a:hover {
    background: rgba(255,255,255,0.1);
    color: white;
    border-left-color: #667eea;
    padding-left: 30px;
}

.menu li a.active {
    background: rgba(102, 126, 234, 0.2);
    color: white;
    border-left-color: #667eea;
}

.content {
    flex: 1;
    padding: 40px;
    overflow-y: auto;
    background: #f7fafc;
}

/* Tables */
table {
    width: 100%;
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 6px rgba(0,0,0,0.07);
    border: 1px solid #e2e8f0;
}

table th {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 18px 20px;
    text-align: left;
    font-weight: 600;
    font-size: 14px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

table td {
    padding: 16px 20px;
    border-bottom: 1px solid #e2e8f0;
    color: #4a5568;
}

table tr:last-child td {
    border-bottom: none;
}

table tr:hover {
    background: #f7fafc;
}

/* Buttons */
.btn {
    padding: 10px 24px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: all 0.3s;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
}

.btn-success {
    background: linear-gradient(135deg, #48bb78 0%, #38a169 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(72, 187, 120, 0.3);
}

.btn-success:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(72, 187, 120, 0.4);
}

.btn-danger {
    background: linear-gradient(135deg, #fc8181 0%, #f56565 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(252, 129, 129, 0.3);
}

.btn-danger:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(252, 129, 129, 0.4);
}

/* Page Header */
.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
}

.page-header h1 {
    font-size: 32px;
    color: #1a202c;
    font-weight: 700;
}

/* Cards */
.card {
    background: white;
    border-radius: 12px;
    padding: 25px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.07);
    border: 1px solid #e2e8f0;
    margin-bottom: 20px;
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        height: auto;
    }
    
    #main-screen {
        flex-direction: column;
    }
}