:root {
    --primary-color: #ef4444;
    --primary-hover: #dc2626;
    --secondary-color: #f97316;
    --success-color: #10b981;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --text-tertiary: #9ca3af;
    --border-color: #e5e7eb;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --transition: all 0.2s ease;
}

* {
    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;
    color: var(--text-primary);
    transition: background 0.5s ease;
}

body.mode-work {
    background: linear-gradient(135deg, #ef4444 0%, #f97316 100%);
}

body.mode-break {
    background: linear-gradient(135deg, #10b981 0%, #06b6d4 100%);
}

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

.header {
    display: flex;
    justify-content: flex-end;
    padding: 1rem 0;
}

.language-selector select {
    padding: 0.5rem 1rem;
    border-radius: var(--radius-md);
    border: 1px solid rgba(255, 255, 255, 0.3);
    background: rgba(255, 255, 255, 0.2);
    color: white;
    font-size: 0.875rem;
    cursor: pointer;
    backdrop-filter: blur(10px);
    transition: var(--transition);
}

.language-selector select:hover {
    background: rgba(255, 255, 255, 0.3);
}

.main-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-top: 1rem;
}

@media (min-width: 1024px) {
    .main-content {
        grid-template-columns: 2fr 1fr;
    }
}

.timer-section {
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    padding: 2rem;
    box-shadow: var(--shadow-xl);
}

.app-title {
    text-align: center;
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

.mode-selector {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 2rem;
}

.mode-btn {
    padding: 0.75rem 1.5rem;
    border: 2px solid var(--border-color);
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
}

.mode-btn:hover {
    background: var(--bg-tertiary);
}

.mode-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.timer-display {
    display: flex;
    justify-content: center;
    margin-bottom: 2rem;
}

.timer-progress {
    position: relative;
    width: 320px;
    height: 320px;
}

.progress-ring {
    transform: rotate(-90deg);
}

.progress-ring-bg {
    fill: none;
    stroke: var(--bg-tertiary);
    stroke-width: 10;
}

.progress-ring-bar {
    fill: none;
    stroke: var(--primary-color);
    stroke-width: 10;
    stroke-linecap: round;
    stroke-dasharray: 942.48;
    stroke-dashoffset: 942.48;
    transition: stroke-dashoffset 1s linear;
}

.timer-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
}

#timerDisplay {
    font-size: 4rem;
    font-weight: 700;
    font-variant-numeric: tabular-nums;
    letter-spacing: -0.05em;
}

.session-info {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-top: 0.5rem;
}

.timer-controls {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 2rem;
}

.control-btn {
    padding: 1rem 2rem;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-md);
}

.control-btn.primary {
    background: var(--primary-color);
    color: white;
}

.control-btn.primary:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.control-btn.secondary {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
}

.control-btn.secondary:hover {
    background: var(--border-color);
}

.settings-section {
    text-align: center;
}

.settings-toggle {
    padding: 0.75rem 1.5rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
}

.settings-toggle:hover {
    background: var(--bg-tertiary);
}

.settings-panel {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: 1.5rem;
    margin-top: 1rem;
    text-align: left;
}

.setting-item {
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.setting-item label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.setting-item input[type="number"] {
    width: 80px;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    text-align: center;
}

.setting-item input[type="checkbox"] {
    width: 1.25rem;
    height: 1.25rem;
    cursor: pointer;
}

.task-section, .history-section {
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    padding: 1.5rem;
    box-shadow: var(--shadow-xl);
}

.task-section h2, .history-section h2 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.task-input-container {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

#taskInput {
    flex: 1;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
}

#taskInput:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.1);
}

.add-task-btn {
    padding: 0.75rem 1.5rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.add-task-btn:hover {
    background: var(--primary-hover);
}

.task-list {
    list-style: none;
    max-height: 300px;
    overflow-y: auto;
}

.task-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    margin-bottom: 0.5rem;
    transition: var(--transition);
}

.task-item:hover {
    background: var(--bg-tertiary);
}

.task-item.completed .task-text {
    text-decoration: line-through;
    color: var(--text-tertiary);
}

.task-item input[type="checkbox"] {
    width: 1.25rem;
    height: 1.25rem;
    cursor: pointer;
    flex-shrink: 0;
}

.task-text {
    flex: 1;
    font-size: 0.875rem;
    color: var(--text-primary);
}

.delete-task {
    width: 1.5rem;
    height: 1.5rem;
    border: none;
    background: transparent;
    color: var(--text-tertiary);
    font-size: 1.25rem;
    cursor: pointer;
    opacity: 0;
    transition: var(--transition);
}

.task-item:hover .delete-task {
    opacity: 1;
}

.delete-task:hover {
    color: var(--primary-color);
}

.task-stats {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
    font-size: 0.875rem;
    color: var(--text-secondary);
    text-align: center;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
    margin-bottom: 1rem;
}

.stat-card {
    background: var(--bg-secondary);
    padding: 1rem;
    border-radius: var(--radius-md);
    text-align: center;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.25rem;
}

.stat-label {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.clear-stats-btn {
    width: 100%;
    padding: 0.75rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
}

.clear-stats-btn:hover {
    background: var(--border-color);
}

@media (max-width: 768px) {
    .timer-progress {
        width: 280px;
        height: 280px;
    }
    
    #timerDisplay {
        font-size: 3rem;
    }
    
    .mode-btn {
        padding: 0.5rem 1rem;
        font-size: 0.75rem;
    }
    
    .control-btn {
        padding: 0.75rem 1.5rem;
        font-size: 0.875rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
}

/* スクロールバーのスタイリング */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
}

::-webkit-scrollbar-thumb {
    background: var(--text-tertiary);
    border-radius: var(--radius-sm);
}

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