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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
    color: #333;
}

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

/* Header */
.header {
    text-align: center;
    margin-bottom: 30px;
    color: white;
}

.header h1 {
    font-size: 3rem;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.2);
}

.subtitle {
    font-size: 1.3rem;
    opacity: 0.95;
}

.streak-badge {
    display: inline-block;
    background: #ff6b6b;
    color: white;
    padding: 10px 20px;
    border-radius: 25px;
    font-size: 1.2rem;
    font-weight: bold;
    margin-top: 10px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
}

/* Cards */
.card {
    background: white;
    border-radius: 20px;
    padding: 30px;
    margin-bottom: 25px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

/* Navigation Buttons */
.nav-buttons {
    display: flex;
    gap: 15px;
    margin-bottom: 25px;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    padding: 15px 30px;
    border: none;
    border-radius: 12px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
    text-align: center;
    min-height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: #f0f0f0;
    color: #333;
}

.btn-secondary:hover {
    background: #e0e0e0;
    transform: translateY(-2px);
}

.btn-success {
    background: linear-gradient(135deg, #11998e 0%, #38ef7d 100%);
    color: white;
}

.btn-success:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(17, 153, 142, 0.4);
}

.btn-warning {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
}

.btn-warning:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(245, 87, 108, 0.4);
}

.btn-large {
    padding: 20px 40px;
    font-size: 1.3rem;
    width: 100%;
}

.btn-small {
    padding: 10px 20px;
    font-size: 0.95rem;
    min-height: auto;
}

.btn-disabled {
    background: #cccccc;
    color: #666;
    cursor: not-allowed;
    opacity: 0.6;
}

/* Form Styles */
.name-form {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.name-input {
    padding: 20px;
    font-size: 1.3rem;
    border: 3px solid #e0e0e0;
    border-radius: 12px;
    transition: border-color 0.3s;
}

.name-input:focus {
    outline: none;
    border-color: #667eea;
}

/* Student Buttons */
.existing-students {
    margin-bottom: 20px;
}

.label {
    font-weight: 600;
    margin-bottom: 15px;
    font-size: 1.1rem;
    color: #666;
}

.student-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin-top: 15px;
}

.divider {
    text-align: center;
    margin: 30px 0;
    position: relative;
}

.divider span {
    background: white;
    padding: 0 20px;
    color: #999;
    font-weight: 600;
    position: relative;
    z-index: 1;
}

.divider::before {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    top: 50%;
    height: 2px;
    background: #e0e0e0;
}

/* Tasks Grid */
.tasks-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
    flex-wrap: wrap;
    gap: 15px;
}

.tasks-header h2 {
    color: white;
    font-size: 2rem;
}

.task-header-buttons {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.tasks-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.task-card {
    background: white;
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.15);
    transition: all 0.3s ease;
}

.task-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
}

.task-card h3 {
    font-size: 1.4rem;
    margin-bottom: 12px;
    color: #333;
}

.task-description {
    color: #666;
    margin-bottom: 15px;
    line-height: 1.5;
}

.task-description-active {
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 20px;
    line-height: 1.6;
    font-size: 1.1rem;
}

.task-meta {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.time-badge, .difficulty-badge {
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
}

.time-badge {
    background: #e3f2fd;
    color: #1976d2;
}

.difficulty-badge {
    background: #fff3e0;
    color: #f57c00;
}

/* Active Task */
.active-task-card {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-align: center;
    scroll-margin-top: 20px;
}

.active-task-card h2 {
    font-size: 1.5rem;
    margin-bottom: 15px;
}

.active-task-card .task-title {
    font-size: 2rem;
    margin-bottom: 25px;
}

.task-active {
    border: 4px solid #667eea;
    background: #f0f4ff;
}

.timer {
    font-size: 4rem;
    font-weight: bold;
    margin: 30px 0 10px 0;
    font-family: 'Courier New', monospace;
    transition: color 0.3s ease;
}

.timer.overtime {
    color: #ff6b6b;
    animation: pulse 1s infinite;
}

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

.timer-progress {
    font-size: 1.2rem;
    margin-bottom: 25px;
    color: rgba(255, 255, 255, 0.9);
    font-weight: 600;
}

/* Upload Form */
.upload-form {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.file-input {
    padding: 15px;
    border: 2px dashed #667eea;
    border-radius: 10px;
    background: #f8f9ff;
    cursor: pointer;
}

.small-text {
    font-size: 0.9rem;
    color: #666;
    margin-top: 10px;
}

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

.stat-card {
    background: white;
    border-radius: 15px;
    padding: 25px;
    text-align: center;
    box-shadow: 0 5px 15px rgba(0,0,0,0.15);
}

.stat-number {
    font-size: 3rem;
    font-weight: bold;
    color: #667eea;
    margin-bottom: 10px;
}

.stat-label {
    font-size: 1.1rem;
    color: #666;
    font-weight: 600;
}

/* Completions List */
.completions-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.completion-item {
    border: 2px solid #e0e0e0;
    border-radius: 12px;
    padding: 20px;
    background: #fafafa;
}

.completion-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
    flex-wrap: wrap;
    gap: 10px;
}

.completion-header h3 {
    font-size: 1.3rem;
    color: #333;
}

.completion-date {
    color: #999;
    font-size: 0.9rem;
}

.completion-description {
    color: #666;
    margin-bottom: 15px;
    line-height: 1.5;
    font-style: italic;
}

.completion-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 15px;
}

.completion-stat {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.completion-stat .label {
    color: #666;
    font-weight: 600;
    margin: 0;
}

.completion-stat .value {
    font-weight: bold;
    color: #333;
}

.score-value {
    padding: 4px 12px;
    border-radius: 12px;
    color: white;
}

.score-high {
    background: #4caf50;
}

.score-medium {
    background: #ff9800;
}

.score-low {
    background: #f44336;
}

.achievement-badge {
    margin-top: 15px;
    padding: 8px 16px;
    background: linear-gradient(135deg, #ffd700 0%, #ffed4e 100%);
    color: #333;
    border-radius: 20px;
    display: inline-block;
    font-weight: bold;
    font-size: 0.95rem;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 60px 30px;
}

.empty-state h2 {
    font-size: 2rem;
    margin-bottom: 15px;
    color: #666;
}

.empty-state p {
    font-size: 1.2rem;
    color: #999;
    margin-bottom: 30px;
}

/* Footer */
.footer {
    text-align: center;
    color: white;
    margin-top: 40px;
    font-size: 1.1rem;
    opacity: 0.9;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header h1 {
        font-size: 2rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .tasks-grid {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: 1fr 1fr;
    }
    
    .timer {
        font-size: 3rem;
    }
    
    .btn {
        font-size: 1rem;
        padding: 12px 24px;
    }
}

/* Edit Task Form */
.edit-task-form {
    display: flex;
    flex-direction: column;
    gap: 25px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.form-group label {
    font-weight: 600;
    font-size: 1.1rem;
    color: #333;
}

.form-input,
.form-textarea {
    padding: 15px;
    font-size: 1.1rem;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-family: inherit;
    transition: border-color 0.3s;
}

.form-input:focus,
.form-textarea:focus {
    outline: none;
    border-color: #667eea;
}

.form-textarea {
    resize: vertical;
    min-height: 80px;
}

.button-group {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

/* Task Header with Edit Button */
.task-header-row {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 12px;
}

.btn-icon {
    background: #f0f0f0;
    border: none;
    border-radius: 8px;
    padding: 8px 12px;
    font-size: 1.2rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-icon:hover {
    background: #667eea;
    transform: scale(1.1);
}

.task-header-row h3 {
    margin: 0;
    flex: 1;
}