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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --danger-color: #dc2626;
    --danger-hover: #b91c1c;
    --warning-color: #f59e0b;
    --warning-hover: #d97706;
    --success-color: #10b981;
    --bg-color: #f9fafb;
    --card-bg: #ffffff;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
}

.screen {
    min-height: 100vh;
}

.hidden {
    display: none !important;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Navbar */
.navbar {
    background-color: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow);
    padding: 15px 0;
    margin-bottom: 30px;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
}

.navbar h1 {
    font-size: 24px;
    color: var(--text-primary);
}

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

#login-screen .card {
    background: var(--card-bg);
    padding: 40px;
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
    max-width: 400px;
    width: 100%;
    text-align: center;
}

#login-screen h1 {
    margin-bottom: 10px;
    font-size: 28px;
}

#login-screen p {
    color: var(--text-secondary);
    margin-bottom: 30px;
}

/* Cards */
.card {
    background-color: var(--card-bg);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 20px;
    margin-bottom: 20px;
}

.section {
    margin-bottom: 40px;
}

.section h2 {
    font-size: 22px;
    margin-bottom: 20px;
    color: var(--text-primary);
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: 10px;
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.stat-card {
    background-color: var(--card-bg);
    border-radius: 8px;
    padding: 20px;
    box-shadow: var(--shadow);
    border-left: 4px solid var(--primary-color);
}

.stat-label {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 8px;
    font-weight: 500;
}

.stat-value {
    font-size: 28px;
    font-weight: bold;
    color: var(--text-primary);
}

.stat-value.active {
    color: var(--success-color);
}

.stat-value.inactive {
    color: var(--text-secondary);
}

/* Forms */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text-primary);
}

.form-group small {
    display: block;
    margin-top: 5px;
    color: var(--text-secondary);
    font-size: 13px;
}

input[type="text"],
input[type="password"],
input[type="number"],
textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 14px;
    font-family: inherit;
    transition: border-color 0.2s;
}

input:focus,
textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

textarea {
    resize: vertical;
}

/* Buttons */
button {
    padding: 12px 24px;
    border: none;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    font-family: inherit;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-hover);
}

.btn-secondary {
    background-color: var(--text-secondary);
    color: white;
}

.btn-secondary:hover {
    background-color: var(--text-primary);
}

.btn-danger {
    background-color: var(--danger-color);
    color: white;
}

.btn-danger:hover {
    background-color: var(--danger-hover);
}

.btn-warning {
    background-color: var(--warning-color);
    color: white;
}

.btn-warning:hover {
    background-color: var(--warning-hover);
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.action-buttons {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

/* Tables */
.table-container {
    background-color: var(--card-bg);
    border-radius: 8px;
    box-shadow: var(--shadow);
    overflow: hidden;
    margin-top: 20px;
    max-height: 500px;
    overflow-y: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
}

thead {
    background-color: var(--bg-color);
    position: sticky;
    top: 0;
}

th {
    padding: 12px;
    text-align: left;
    font-weight: 600;
    color: var(--text-primary);
    border-bottom: 2px solid var(--border-color);
}

td {
    padding: 12px;
    border-bottom: 1px solid var(--border-color);
}

tbody tr:hover {
    background-color: var(--bg-color);
}

.status-badge {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 500;
}

.status-sent {
    background-color: #d1fae5;
    color: #065f46;
}

.status-failed {
    background-color: #fee2e2;
    color: #991b1b;
}

.status-pending {
    background-color: #fef3c7;
    color: #92400e;
}

/* Toast */
.toast {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background-color: var(--text-primary);
    color: white;
    padding: 16px 24px;
    border-radius: 8px;
    box-shadow: var(--shadow-lg);
    z-index: 1000;
    animation: slideIn 0.3s ease-out;
}

.toast.success {
    background-color: var(--success-color);
}

.toast.error {
    background-color: var(--danger-color);
}

@keyframes slideIn {
    from {
        transform: translateX(400px);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* Error Message */
.error {
    color: var(--danger-color);
    background-color: #fee2e2;
    padding: 12px;
    border-radius: 6px;
    margin-top: 15px;
    font-size: 14px;
}

/* Help Text */
.help-text {
    margin-top: 15px;
    padding: 15px;
    background-color: var(--bg-color);
    border-radius: 6px;
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* Responsive */
@media (max-width: 768px) {
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .action-buttons {
        flex-direction: column;
    }
    
    .action-buttons button {
        width: 100%;
    }
    
    .navbar .container {
        flex-direction: column;
        gap: 15px;
    }
    
    table {
        font-size: 13px;
    }
    
    th, td {
        padding: 8px;
    }
}

/* Signal Setup Section */
.status-box {
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 20px;
    text-align: center;
}

.status-box.success {
    background-color: #d1fae5;
    border-color: var(--success-color);
    color: #065f46;
}

.status-box.warning {
    background-color: #fef3c7;
    border-color: var(--warning-color);
    color: #92400e;
}

.status-box.error {
    background-color: #fee2e2;
    border-color: var(--danger-color);
    color: #991b1b;
}

#signal-setup h3 {
    font-size: 18px;
    margin: 20px 0 15px 0;
    color: var(--text-primary);
}

#qr-code-container {
    margin-top: 20px;
    padding: 20px;
    background-color: var(--bg-color);
    border-radius: 8px;
    text-align: center;
}

#qr-code {
    display: inline-block;
    padding: 20px;
    background-color: white;
    border-radius: 8px;
    margin-bottom: 15px;
}

#qr-code canvas,
#qr-code img {
    display: block;
    margin: 0 auto;
}

input[type="tel"] {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 14px;
    font-family: inherit;
    transition: border-color 0.2s;
}