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

:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --primary-light: #818cf8;
    --secondary-color: #6b7280;
    --success-color: #10b981;
    --error-color: #ef4444;
    --border-color: #e5e7eb;
    --background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --surface: #ffffff;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --text-hover: #ffffff;
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.08);
    --shadow-md: 0 8px 16px -4px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background: #f3f4f6;
    min-height: 100vh;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

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

/* View Management */
.view {
    min-height: 100vh;
}

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

#login-view::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: float 20s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) rotate(0deg); }
    33% { transform: translate(30px, -30px) rotate(120deg); }
    66% { transform: translate(-20px, 20px) rotate(240deg); }
}

.login-container {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    padding: 48px;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    width: 100%;
    max-width: 440px;
    margin: 20px;
    border: 1px solid rgba(255, 255, 255, 0.3);
    position: relative;
    z-index: 1;
}

.login-container h1 {
    text-align: center;
    margin-bottom: 30px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 2.5rem;
    font-weight: 700;
}

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

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

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 15px;
    transition: all 0.3s ease;
    font-family: inherit;
    background: white;
}

.form-group 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='%236b7280' d='M10.293 3.293L6 7.586 1.707 3.293A1 1 0 00.293 4.707l5 5a1 1 0 001.414 0l5-5a1 1 0 10-1.414-1.414z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 16px center;
    padding-right: 40px;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.15);
    transform: translateY(-1px);
}

.form-group textarea {
    resize: vertical;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.error-message {
    display: block;
    color: var(--error-color);
    font-size: 12px;
    margin-top: 4px;
    min-height: 18px;
}

/* Buttons */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: var(--radius-md);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    position: relative;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover:not(:disabled) {
    background: linear-gradient(135deg, var(--primary-hover) 0%, var(--primary-color) 100%);
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(99, 102, 241, 0.4);
}

.btn-secondary {
    background: var(--surface);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover:not(:disabled) {
    background: var(--background);
    color : var(--text-hover);
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.form-actions {
    display: flex;
    gap: 12px;
    margin-top: 20px;
}

/* Spinner */
.spinner {
    width: 16px;
    height: 16px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
}

.loading .spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--primary-color);
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Header */
.app-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 24px 0;
    box-shadow: var(--shadow-lg);
}

.app-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.app-header h1 {
    color: white;
    font-size: 2rem;
    font-weight: 700;
    text-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.user-info {
    display: flex;
    align-items: center;
    gap: 20px;
}

.user-greeting {
    color: rgba(255, 255, 255, 0.9);
    font-size: 15px;
}

.user-greeting strong {
    color: white;
    font-weight: 600;
}

/* Main Content */
main {
    padding: 40px 20px;
}

/* Create Section */
.create-section {
    background: var(--surface);
    padding: 36px;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    margin-bottom: 40px;
    margin-top: 40px;
    border: 1px solid rgba(99, 102, 241, 0.1);
    transition: all 0.3s ease;
}

.create-section:hover {
    box-shadow: var(--shadow-xl);
    transform: translateY(-2px);
    color : var(--text-hover);
}

.create-section h2 {
    margin-bottom: 24px;
    color: var(--text-primary);
    font-size: 1.75rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 12px;
}


/* TODOs Section */
.todos-section {
    background: var(--surface);
    padding: 36px;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    border: 1px solid rgba(99, 102, 241, 0.1);
}

.todos-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
    flex-wrap: wrap;
    gap: 16px;
}

.todos-header h2 {
    color: var(--text-primary);
    font-size: 1.5rem;
}

/* Filter Buttons */
.filter-buttons {
    display: flex;
    gap: 8px;
}

.filter-btn {
    padding: 6px 16px;
    border: 1px solid var(--border-color);
    background: var(--surface);
    border-radius: var(--radius-md);
    font-size: 14px;
    cursor: pointer;
    transition: all 0.2s;
    color: var(--text-secondary);
}

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

.filter-btn.active {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: white;
    border-color: transparent;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
    transform: translateY(-1px);
}

/* Loading & Empty States */
.loading,
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.empty-state p {
    font-size: 1.1rem;
}

/* TODO List */
.todos-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

/* TODO Item */
.todo-item {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.9) 0%, rgba(249, 250, 251, 0.9) 100%);
    border: 2px solid transparent;
    border-radius: var(--radius-lg);
    padding: 20px;
    transition: all 0.3s ease;
    animation: slideIn 0.4s ease-out;
    position: relative;
    overflow: hidden;
}

.todo-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.05) 0%, rgba(129, 140, 248, 0.05) 100%);
    opacity: 0;
    transition: opacity 0.3s ease;
    pointer-events: none;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.todo-item:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
    color : var(--text-hover);
    border-color: rgba(99, 102, 241, 0.2);
}

.todo-item:hover::before {
    opacity: 1;
    color : var(--text-hover);
}

.todo-item.completed {
    opacity: 0.65;
    background: linear-gradient(135deg, rgba(249, 250, 251, 0.9) 0%, rgba(243, 244, 246, 0.9) 100%);
}

.todo-item.completed .todo-content .todo-name {
    text-decoration: line-through;
    color: var(--text-secondary);
}

.todo-main {
    display: flex;
    gap: 12px;
}

.todo-checkbox {
    flex-shrink: 0;
    margin-top: 4px;
}

.todo-checkbox input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: var(--primary-color);
}

.todo-content {
    flex: 1;
    min-width: 0;
}

.todo-name {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
    word-wrap: break-word;
}

.todo-description {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 8px;
    white-space: pre-wrap;
    word-wrap: break-word;
}

.todo-subject {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: white;
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    box-shadow: 0 2px 8px rgba(99, 102, 241, 0.25);
    letter-spacing: 0.3px;
}

.todo-actions {
    display: flex;
    gap: 8px;
    margin-top: 12px;
}

.btn-icon {
    padding: 6px 14px;
    font-size: 13px;
}

.btn-edit {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: white;
    box-shadow: 0 2px 8px rgba(99, 102, 241, 0.25);
}

.btn-edit:hover {
    background: linear-gradient(135deg, var(--primary-hover) 0%, var(--primary-color) 100%);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.35);
    transform: translateY(-2px);
    color : var(--text-hover);
}

.btn-delete {
    background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
    color: white;
    box-shadow: 0 2px 8px rgba(239, 68, 68, 0.25);
}

.btn-delete:hover {
    background: linear-gradient(135deg, #dc2626 0%, #b91c1c 100%);
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.35);
    transform: translateY(-2px);
    color : var(--text-hover);
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: 20px;
}

.modal-content {
    background: var(--surface);
    border-radius: var(--radius-xl);
    max-width: 540px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: var(--shadow-xl);
    animation: modalSlideIn 0.3s ease-out;
    border: 1px solid rgba(99, 102, 241, 0.1);
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: scale(0.95) translateY(-20px);
    }
    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px 24px 16px;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h2 {
    font-size: 1.5rem;
    color: var(--text-primary);
}

.close-btn {
    background: none;
    border: none;
    font-size: 28px;
    cursor: pointer;
    color: var(--text-secondary);
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-sm);
    transition: all 0.2s;
}

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

.modal-content form {
    padding: 24px;
}

/* Toast Notification */
.toast {
    position: fixed;
    bottom: 24px;
    right: 24px;
    background: var(--text-primary);
    color: white;
    padding: 16px 24px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    z-index: 2000;
    animation: toastSlideIn 0.3s ease-out;
    max-width: 400px;
}

@keyframes toastSlideIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

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

/* Auth Toggle */
.auth-toggle {
    margin-top: 24px;
    text-align: center;
    color: var(--text-secondary);
    font-size: 14px;
}

.auth-toggle a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    transition: all 0.2s ease;
}

.auth-toggle a:hover {
    opacity: 0.8;
    color : var(--text-hover);
}

/* Responsive Design */
@media (max-width: 768px) {
    .app-header .container {
        flex-direction: column;
        gap: 16px;
        align-items: flex-start;
    }

    .user-info {
        width: 100%;
        justify-content: space-between;
    }

    .form-row {
        grid-template-columns: 1fr;
    }

    .todos-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .filter-buttons {
        width: 100%;
        justify-content: flex-start;
    }

    .create-section,
    .todos-section {
        padding: 20px;
    }

    main {
        padding: 20px 10px;
    }

    .toast {
        left: 20px;
        right: 20px;
        bottom: 20px;
    }

    .todo-actions {
        flex-wrap: wrap;
    }
}

@media (max-width: 480px) {
    .login-container {
        padding: 30px 20px;
    }

    .app-header h1 {
        font-size: 1.5rem;
    }

    .create-section h2,
    .todos-header h2 {
        font-size: 1.25rem;
    }

    .todo-name {
        font-size: 1rem;
    }

    .form-actions {
        flex-direction: column;
    }

    .form-actions .btn {
        width: 100%;
        justify-content: center;
    }

    .user-greeting {
        font-size: 14px;
    }
}