/* CSS Variables for Theming */
:root {
    --bg-gradient-start: #667eea;
    --bg-gradient-end: #764ba2;
    --header-bg: rgba(255, 255, 255, 0.1);
    --header-border: rgba(148, 163, 184, 0.1);
    --card-bg: white;
    --card-border: rgba(148, 163, 184, 0.1);
    --text-primary: #333;
    --text-secondary: #666;
    --text-light: white;
    --input-bg: white;
    --input-border: #e0e0e0;
    --input-border-focus: #667eea;
    --tab-bg: rgba(255, 255, 255, 0.2);
    --tab-bg-hover: rgba(255, 255, 255, 0.3);
    --tab-active-bg: white;
    --tab-active-text: #667eea;
    --tab-border: transparent;
    --btn-primary-bg: white;
    --btn-primary-text: #667eea;
    --btn-primary-hover: white;
    --btn-secondary-bg: rgba(255, 255, 255, 0.2);
    --btn-secondary-border: rgba(255, 255, 255, 0.3);
    --brand-color: #667eea;
    --item-border: #e0e0e0;
    --item-hover-bg: #f8f9fa;
    --alert-success-bg: #d4edda;
    --alert-success-text: #155724;
    --alert-success-border: #c3e6cb;
    --alert-error-bg: #f8d7da;
    --alert-error-text: #721c24;
    --alert-error-border: #f5c6cb;
    --alert-info-bg: #d1ecf1;
    --alert-info-text: #0c5460;
    --alert-info-border: #bee5eb;
    --snackbar-bg: #333;
    --snackbar-text: #fff;
    --snackbar-border: rgba(148, 163, 184, 0.3);
}

[data-theme="dark"] {
    --bg-gradient-start: #0f172a;
    --bg-gradient-end: #1e293b;
    --header-bg: rgba(30, 41, 59, 0.8);
    --header-border: rgba(148, 163, 184, 0.1);
    --card-bg: #1e293b;
    --card-border: rgba(148, 163, 184, 0.1);
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    --text-light: #e2e8f0;
    --input-bg: #0f172a;
    --input-border: #334155;
    --input-border-focus: #3b82f6;
    --tab-bg: rgba(30, 41, 59, 0.6);
    --tab-bg-hover: rgba(30, 41, 59, 0.8);
    --tab-active-bg: #3b82f6;
    --tab-active-text: white;
    --tab-border: rgba(148, 163, 184, 0.2);
    --btn-primary-bg: #3b82f6;
    --btn-primary-text: white;
    --btn-primary-hover: #2563eb;
    --btn-secondary-bg: rgba(71, 85, 105, 0.5);
    --btn-secondary-border: rgba(148, 163, 184, 0.3);
    --brand-color: #3b82f6;
    --item-border: #334155;
    --item-hover-bg: rgba(30, 41, 59, 0.6);
    --alert-success-bg: rgba(34, 197, 94, 0.2);
    --alert-success-text: #4ade80;
    --alert-success-border: rgba(34, 197, 94, 0.3);
    --alert-error-bg: rgba(239, 68, 68, 0.2);
    --alert-error-text: #f87171;
    --alert-error-border: rgba(239, 68, 68, 0.3);
    --alert-info-bg: rgba(59, 130, 246, 0.2);
    --alert-info-text: #60a5fa;
    --alert-info-border: rgba(59, 130, 246, 0.3);
    --snackbar-bg: #475569;
    --snackbar-text: #f1f5f9;
    --snackbar-border: rgba(148, 163, 184, 0.5);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    min-height: 100vh;
    padding: 0;
    transition: background 0.3s ease;
}

/* Header */
.header {
    background: var(--header-bg);
    backdrop-filter: blur(10px);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    border-bottom: 1px solid var(--header-border);
    transition: background 0.3s ease, border-color 0.3s ease;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-light);
    font-size: 1.5rem;
    font-weight: 700;
    text-decoration: none;
}

.user-section {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.user-info {
    color: var(--text-light);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: opacity 0.3s ease;
}

.user-info:hover {
    opacity: 0.8;
}

/* Buttons */
.btn {
    padding: 0.6rem 1.2rem;
    border-radius: 8px;
    border: none;
    cursor: pointer;
    font-weight: 600;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s;
}

.btn-primary {
    background: var(--btn-primary-bg);
    color: var(--btn-primary-text);
    transition: all 0.3s ease;
}

.btn-primary:hover {
    background: var(--btn-primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.btn-secondary {
    background: var(--btn-secondary-bg);
    color: var(--text-light);
    border: 1px solid var(--btn-secondary-border);
    transition: all 0.3s ease;
}

.btn-secondary:hover {
    background: var(--tab-bg-hover);
}

.btn-small {
    padding: 0.4rem 0.8rem;
    font-size: 0.85rem;
}

.btn-danger {
    background: #dc3545;
    color: white;
}

.btn-danger:hover {
    background: #c82333;
}

/* Form Styles */
.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
    transition: color 0.3s ease;
}

.form-group input[type="text"],
.form-group input[type="number"],
.form-group input[type="email"],
.form-group input[type="password"],
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--input-border);
    border-radius: 8px;
    background: var(--input-bg);
    color: var(--text-primary);
    font-size: 1rem;
    transition: all 0.3s ease;
}

.form-group input[type="text"]:focus,
.form-group input[type="number"]:focus,
.form-group input[type="email"]:focus,
.form-group input[type="password"]:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--input-border-focus);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.form-group input[type="text"]::placeholder,
.form-group input[type="number"]::placeholder,
.form-group input[type="email"]::placeholder,
.form-group input[type="password"]::placeholder,
.form-group textarea::placeholder {
    color: var(--text-secondary);
    opacity: 0.6;
}

.form-group input[type="checkbox"] {
    width: auto;
    margin-right: 0.5rem;
    cursor: pointer;
}

.form-group label:has(input[type="checkbox"]) {
    display: flex;
    align-items: center;
    cursor: pointer;
    font-weight: 500;
}

select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%2394a3b8' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.75rem center;
    padding-right: 2.5rem;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
}

/* Cards */
.card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    border: 1px solid var(--card-border);
    margin-bottom: 1rem;
    transition: background 0.3s ease, border-color 0.3s ease;
}

.card h3 {
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Loading */
.loading {
    text-align: center;
    padding: 2rem;
    color: var(--text-secondary);
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .header {
        padding: 1rem;
        flex-direction: column;
        gap: 1rem;
    }

    .card {
        padding: 1rem;
    }
}