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

:root {
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --secondary-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --accent-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --dark-gradient: linear-gradient(135deg, #232526 0%, #414345 100%);
    --glass-bg: rgba(255, 255, 255, 0.25);
    --glass-border: rgba(255, 255, 255, 0.18);
    --text-primary: #2d3748;
    --text-secondary: #718096;
    --shadow-soft: 0 8px 32px rgba(31, 38, 135, 0.37);
    --shadow-hover: 0 15px 35px rgba(31, 38, 135, 0.5);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', roboto, sans-serif;
    background: linear-gradient(-45deg, #ee7752, #e73c7e, #23a6d5, #23d5ab);
    background-size: 400% 400%;
    animation: gradientShift 15s ease infinite;
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
}

@keyframes gradientShift {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

/* Floating particles animation */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Ccircle cx='30' cy='30' r='2'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    pointer-events: none;
    animation: float 20s linear infinite;
    z-index: -1;
}

@keyframes float {
    0% { transform: translateY(0px); }
    100% { transform: translateY(-100vh); }
}

/* Layout */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 20px;
}

.header {
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 0 0 20px 20px;
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 20px 0;
    box-shadow: var(--shadow-soft);
    transition: var(--transition);
}

.header:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.header h1 {
    font-size: 28px;
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-align: center;
    letter-spacing: -0.02em;
    animation: glow 2s ease-in-out infinite alternate;
}

@keyframes glow {
    from { filter: drop-shadow(0 0 5px rgba(102, 126, 234, 0.3)); }
    to { filter: drop-shadow(0 0 20px rgba(102, 126, 234, 0.6)); }
}

.main {
    padding: 40px 0;
}

/* Glassmorphism Cards */
.glass-card {
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    box-shadow: var(--shadow-soft);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.glass-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.1), transparent);
    transition: left 0.5s;
}

.glass-card:hover::before {
    left: 100%;
}

.glass-card:hover {
    transform: translateY(-8px) scale(1.02);
    box-shadow: var(--shadow-hover);
}

/* Auth Form */
.auth-form {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    padding: 40px;
    border-radius: 24px;
    box-shadow: var(--shadow-soft);
    max-width: 450px;
    margin: 60px auto;
    border: 1px solid var(--glass-border);
    position: relative;
    overflow: hidden;
    animation: slideUp 0.6s ease-out;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.auth-form::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: conic-gradient(from 0deg, transparent, rgba(255,255,255,0.1), transparent);
    animation: rotate 4s linear infinite;
    z-index: -1;
}

@keyframes rotate {
    100% { transform: rotate(360deg); }
}

.auth-form h2 {
    margin-bottom: 32px;
    text-align: center;
    font-size: 32px;
    font-weight: 700;
    background: var(--secondary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.form-group {
    margin-bottom: 24px;
    position: relative;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 14px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.form-group input, .form-group textarea {
    width: 100%;
    padding: 16px 20px;
    background: rgba(255, 255, 255, 0.1);
    border: 2px solid rgba(255, 255, 255, 0.2);
    border-radius: 12px;
    font-size: 16px;
    color: var(--text-primary);
    backdrop-filter: blur(10px);
    transition: var(--transition);
    position: relative;
}

.form-group input::placeholder, .form-group textarea::placeholder {
    color: rgba(45, 55, 72, 0.5);
}

.form-group input:focus, .form-group textarea:focus {
    outline: none;
    border-color: rgba(102, 126, 234, 0.6);
    background: rgba(255, 255, 255, 0.2);
    box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.1);
    transform: scale(1.02);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 28px;
    background: var(--primary-gradient);
    color: white;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    text-decoration: none;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
    transition: left 0.5s;
}

.btn:hover::before {
    left: 100%;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
}

.btn:active {
    transform: translateY(0);
    transition: transform 0.1s;
}

.btn-sm {
    padding: 8px 16px;
    font-size: 14px;
    border-radius: 8px;
}

.btn-danger {
    background: var(--secondary-gradient);
    box-shadow: 0 4px 15px rgba(245, 87, 108, 0.3);
}

.btn-danger:hover {
    box-shadow: 0 8px 25px rgba(245, 87, 108, 0.4);
}

.btn-secondary {
    background: var(--dark-gradient);
    box-shadow: 0 4px 15px rgba(65, 67, 69, 0.3);
}

.btn-secondary:hover {
    box-shadow: 0 8px 25px rgba(65, 67, 69, 0.4);
}

/* Notes Section */
.notes-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 32px;
    padding: 24px;
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    border-radius: 16px;
    border: 1px solid var(--glass-border);
    animation: fadeIn 0.6s ease-out;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.notes-header h2 {
    font-size: 28px;
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.notes-header div {
    display: flex;
    gap: 12px;
}

.notes-list {
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    border-radius: 20px;
    box-shadow: var(--shadow-soft);
    border: 1px solid var(--glass-border);
    overflow: hidden;
}

.note-item {
    padding: 24px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    transition: var(--transition);
    position: relative;
    background: rgba(255, 255, 255, 0.05);
}

.note-item:last-child {
    border-bottom: none;
}

.note-item:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateX(8px);
    box-shadow: inset 4px 0 0 rgba(102, 126, 234, 0.6);
}

.note-content h3 {
    font-size: 20px;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text-primary);
}

.note-content p {
    color: var(--text-secondary);
    font-size: 14px;
    margin-bottom: 12px;
    line-height: 1.5;
}

.note-meta {
    font-size: 12px;
    color: rgba(113, 128, 150, 0.8);
    font-weight: 500;
}

.note-actions {
    display: flex;
    gap: 8px;
    opacity: 0;
    transition: var(--transition);
}

.note-item:hover .note-actions {
    opacity: 1;
}

.empty-state {
    text-align: center;
    padding: 80px 24px;
    color: var(--text-secondary);
    font-size: 18px;
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    border-radius: 20px;
    border: 2px dashed rgba(255, 255, 255, 0.2);
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 0.7; }
    50% { opacity: 1; }
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(8px);
    z-index: 1000;
    animation: modalFadeIn 0.3s ease-out;
}

@keyframes modalFadeIn {
    from {
        opacity: 0;
        backdrop-filter: blur(0px);
    }
    to {
        opacity: 1;
        backdrop-filter: blur(8px);
    }
}

.modal.show {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    border-radius: 24px;
    padding: 32px;
    width: 90%;
    max-width: 600px;
    max-height: 80vh;
    overflow-y: auto;
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-hover);
    animation: modalSlideIn 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
    position: relative;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: scale(0.8) translateY(40px);
    }
    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
    padding-bottom: 16px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.modal-header h3 {
    font-size: 24px;
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.close-btn {
    background: none;
    border: none;
    font-size: 28px;
    cursor: pointer;
    color: var(--text-secondary);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.close-btn:hover {
    background: rgba(245, 87, 108, 0.1);
    color: #f5576c;
    transform: rotate(90deg);
}

.form-group textarea {
    min-height: 140px;
    resize: vertical;
    font-family: inherit;
}

.modal-actions {
    display: flex;
    gap: 12px;
    justify-content: flex-end;
    margin-top: 24px;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: var(--primary-gradient);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--secondary-gradient);
}

/* Loading Animation */
.loading {
    position: relative;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top: 2px solid #fff;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 0 16px;
    }
    
    .header h1 {
        font-size: 24px;
    }
    
    .auth-form {
        padding: 24px;
        margin: 20px auto;
    }
    
    .notes-header {
        flex-direction: column;
        gap: 16px;
        align-items: stretch;
        text-align: center;
    }
    
    .notes-header div {
        justify-content: center;
    }
    
    .note-item {
        flex-direction: column;
        gap: 16px;
    }
    
    .note-actions {
        align-self: flex-end;
        opacity: 1;
    }
    
    .modal-content {
        padding: 20px;
        margin: 20px;
        width: calc(100% - 40px);
    }
    
    .modal-actions {
        flex-direction: column-reverse;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .auth-form {
        margin: 10px auto;
        padding: 20px;
    }
    
    .notes-header {
        padding: 16px;
    }
    
    .note-item {
        padding: 16px;
    }
    
    .modal-content {
        margin: 10px;
        width: calc(100% - 20px);
    }
}

/* Hidden class */
.hidden {
    display: none !important;
}

/* Performance optimizations */
.glass-card, .auth-form, .modal-content, .notes-list {
    will-change: transform;
}

/* Focus states for accessibility */
.btn:focus, input:focus, textarea:focus {
    outline: 2px solid rgba(102, 126, 234, 0.5);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --glass-bg: rgba(255, 255, 255, 0.9);
        --glass-border: rgba(0, 0, 0, 0.3);
        --text-primary: #000;
        --text-secondary: #333;
    }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}