/* Reset và base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f5f5f5;
}

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

/* Header styles */
.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1rem 0;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

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

.logo a {
    color: white;
    text-decoration: none;
    font-size: 1.5rem;
    font-weight: bold;
}

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

.nav-link {
    color: white;
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 5px;
    transition: background-color 0.3s;
}

.nav-link:hover {
    background-color: rgba(255,255,255,0.1);
}

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

.username {
    font-weight: 500;
}

.logout {
    background-color: rgba(255,255,255,0.2);
}

.logout:hover {
    background-color: rgba(255,255,255,0.3);
}

/* Main content */
.main {
    min-height: calc(100vh - 140px);
    padding: 2rem 0;
}

/* Alert messages */
.alert {
    padding: 1rem;
    margin-bottom: 1rem;
    border-radius: 5px;
    border-left: 4px solid;
}

.alert-error {
    background-color: #fee;
    border-color: #f56565;
    color: #c53030;
}

.alert-success {
    background-color: #f0fff4;
    border-color: #48bb78;
    color: #2f855a;
}

/* Login form */
.login-container {
    max-width: 400px;
    margin: 2rem auto;
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

.login-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-weight: 500;
    color: #555;
}

.form-group input,
.form-group textarea {
    padding: 0.75rem;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

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

.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 5px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
    text-align: center;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background-color: #6c757d;
    color: white;
}

.btn-secondary:hover {
    background-color: #5a6268;
}

.btn-danger {
    background-color: #e53e3e;
    color: white;
}

.btn-danger:hover {
    background-color: #c53030;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(229, 62, 62, 0.4);
}

/* Project grid */
.projects-grid {
    position: relative;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.project-card {
    background: white;
    border-radius: 10px;
    padding: 1.5rem;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s, box-shadow 0.3s;
    border: 1px solid #e1e5e9;
    cursor: grab;
    position: relative;
}

.project-card:active {
    cursor: grabbing;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.15);
}

.drag-handle {
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
    color: #a0aec0;
    font-size: 1.2rem;
    cursor: grab;
    user-select: none;
}

.drag-handle:active {
    cursor: grabbing;
}

.project-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: #2d3748;
    margin-bottom: 0.5rem;
    line-height: 1.3;
    padding-right: 2rem;
}

.project-description {
    color: #718096;
    margin-bottom: 1rem;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.project-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid #e2e8f0;
}

.project-date {
    font-size: 0.875rem;
    color: #a0aec0;
}

/* Drop zones */
.drop-zones {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    pointer-events: none;
    z-index: 10;
}

.drop-zone {
    height: 3px;
    background: linear-gradient(90deg, transparent, #667eea, transparent);
    border-radius: 2px;
    opacity: 0.7;
    transition: opacity 0.3s;
}

.drop-zone:hover {
    opacity: 1;
}

/* Project detail view */
.project-detail {
    background: white;
    border-radius: 10px;
    padding: 2rem;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    margin-top: 2rem;
}

.project-detail h1 {
    color: #2d3748;
    margin-bottom: 1rem;
    font-size: 2rem;
}

.project-detail .description {
    background-color: #f7fafc;
    padding: 1.5rem;
    border-radius: 8px;
    border-left: 4px solid #667eea;
    margin: 1rem 0;
    line-height: 1.7;
    white-space: pre-wrap;
}

.project-detail .meta {
    color: #718096;
    font-size: 0.9rem;
    margin-top: 1rem;
}

/* Create project form */
.create-form {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.create-form h1 {
    color: #2d3748;
    margin-bottom: 1.5rem;
    text-align: center;
}

/* Edit form */
.edit-form {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.edit-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.edit-header h1 {
    color: #2d3748;
    margin: 0;
}

/* Delete confirmation */
.delete-confirmation {
    max-width: 600px;
    margin: 0 auto;
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.delete-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.delete-header h1 {
    color: #2d3748;
    margin: 0;
}

.warning-box {
    background-color: #fff5f5;
    border: 1px solid #fed7d7;
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 2rem;
}

.warning-box h2 {
    color: #c53030;
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

.warning-box p {
    color: #2d3748;
    margin-bottom: 0.5rem;
}

.project-preview {
    background-color: #f7fafc;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 2rem;
}

.project-preview h3 {
    color: #2d3748;
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

.preview-item {
    margin-bottom: 1rem;
}

.preview-item label {
    font-weight: 600;
    color: #4a5568;
    display: block;
    margin-bottom: 0.25rem;
}

.preview-item span {
    color: #2d3748;
}

.description-preview {
    background-color: white;
    padding: 0.75rem;
    border-radius: 4px;
    border: 1px solid #e2e8f0;
    color: #4a5568;
    font-style: italic;
}

.confirmation-group {
    margin-bottom: 2rem;
}

.confirmation-group label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    padding: 0.75rem;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.2s;
}

.confirmation-group label:hover {
    background-color: #f7fafc;
}

.confirmation-group input[type="radio"] {
    margin: 0;
}

/* Change password */
.change-password-container {
    max-width: 500px;
    margin: 0 auto;
}

.change-password-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.change-password-header h1 {
    color: #2d3748;
    margin: 0;
}

.change-password-form {
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.form-help {
    color: #718096;
    font-size: 0.875rem;
    margin-top: 0.25rem;
    display: block;
}

.password-strength {
    margin: 1rem 0;
    padding: 1rem;
    background-color: #f7fafc;
    border-radius: 5px;
}

.strength-bar {
    width: 100%;
    height: 8px;
    background-color: #e2e8f0;
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 0.5rem;
}

.strength-fill {
    height: 100%;
    width: 0%;
    transition: width 0.3s ease, background-color 0.3s ease;
}

.strength-text {
    font-size: 0.875rem;
    font-weight: 600;
    text-align: center;
}

.password-tips {
    background-color: #f0fff4;
    border: 1px solid #9ae6b4;
    border-radius: 8px;
    padding: 1.5rem;
}

.password-tips h3 {
    color: #2f855a;
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

.password-tips ul {
    margin: 0;
    padding-left: 1.5rem;
}

.password-tips li {
    color: #2d3748;
    margin-bottom: 0.5rem;
}

/* Form actions */
.form-actions {
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
    margin-top: 2rem;
}

/* Project actions */
.project-actions {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

/* Color picker */
.color-picker {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.color-input {
    width: 50px;
    height: 40px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}

.color-options {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.color-option {
    width: 30px;
    height: 30px;
    border-radius: 50%;
    cursor: pointer;
    border: 2px solid #ddd;
    transition: transform 0.2s, border-color 0.2s;
}

.color-option:hover {
    transform: scale(1.1);
    border-color: #333;
}

#random-color {
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
}

/* Footer */
.footer {
    background-color: #2d3748;
    color: white;
    text-align: center;
    padding: 1rem 0;
    margin-top: 2rem;
}

/* Responsive design */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav {
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .user-menu {
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .project-card {
        margin: 0 1rem;
    }
    
    .container {
        padding: 0 15px;
    }
    
    .create-form,
    .edit-form,
    .project-detail,
    .delete-confirmation,
    .change-password-form {
        margin: 1rem;
        padding: 1.5rem;
    }
    
    .edit-header,
    .delete-header,
    .change-password-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .project-actions {
        width: 100%;
        justify-content: flex-start;
    }
    
    .form-actions {
        flex-direction: column;
    }
    
    .color-picker {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .color-options {
        justify-content: flex-start;
    }
}

@media (max-width: 480px) {
    .nav {
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .project-meta {
        flex-direction: column;
        gap: 0.5rem;
        align-items: flex-start;
    }
}