:root {
    --bg: #f0f2f5;
    --surface: #ffffff;
    --surface-hover: #f8f9fa;
    --text: #2d3436;
    --text-secondary: #636e72;
    --border: #dfe6e9;
    --primary: #6c5ce7;
    --primary-hover: #5a4bd1;
    --primary-light: rgba(108, 92, 231, 0.1);
    --success: #00b894;
    --danger: #e17055;
    --shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.12);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: 0.2s ease;
}

[data-theme="dark"] {
    --bg: #1a1a2e;
    --surface: #16213e;
    --surface-hover: #1c2a4a;
    --text: #eaeaea;
    --text-secondary: #a0a0b0;
    --border: #2a2a4a;
    --primary-light: rgba(108, 92, 231, 0.2);
    --shadow: 0 2px 12px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.4);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    transition: background var(--transition), color var(--transition);
}

.app {
    max-width: 900px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.header h1 {
    font-size: 1.8rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary), #a29bfe);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.date-display {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.header-right {
    display: flex;
    align-items: center;
    gap: 10px;
}

.btn-primary {
    background: var(--primary);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: background var(--transition), transform var(--transition);
}

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
}

.btn-full {
    width: 100%;
    padding: 14px;
}

.btn-icon {
    background: var(--surface);
    border: 1px solid var(--border);
    width: 40px;
    height: 40px;
    border-radius: var(--radius-sm);
    font-size: 1.2rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background var(--transition);
}

.btn-icon:hover {
    background: var(--surface-hover);
}

.btn-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: background var(--transition);
}

.btn-close:hover {
    background: var(--surface-hover);
}

/* Stats Bar */
.stats-bar {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    margin-bottom: 28px;
}

.stat-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px;
    text-align: center;
    transition: transform var(--transition), box-shadow var(--transition);
}

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

.stat-value {
    display: block;
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--primary);
}

.stat-label {
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-top: 4px;
    display: block;
}

/* Main Layout */
.main {
    display: flex;
    flex-direction: column;
    gap: 28px;
}

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

.section-header h2 {
    font-size: 1.2rem;
    font-weight: 600;
}

.section-subtitle {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Habit Card */
.habits-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.habit-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 20px;
    display: flex;
    align-items: center;
    gap: 14px;
    transition: transform var(--transition), box-shadow var(--transition);
    position: relative;
    overflow: hidden;
    cursor: pointer;
}

.habit-card::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 4px;
    background: var(--habit-color, var(--primary));
}

.habit-card:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

.habit-card.completed {
    background: rgba(0, 184, 148, 0.07);
}

.habit-card.completed .habit-name {
    text-decoration: line-through;
    color: var(--text-secondary);
}

.habit-emoji {
    font-size: 1.8rem;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--primary-light);
    border-radius: var(--radius-sm);
    flex-shrink: 0;
}

.habit-info {
    flex: 1;
    min-width: 0;
}

.habit-name {
    font-weight: 600;
    font-size: 1rem;
    margin-bottom: 4px;
}

.habit-progress-bar {
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    overflow: hidden;
    width: 100%;
}

.habit-progress-fill {
    height: 100%;
    border-radius: 3px;
    transition: width 0.4s ease;
}

.habit-count {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 4px;
}

.habit-actions {
    display: flex;
    align-items: center;
    gap: 8px;
}

.btn-check {
    width: 42px;
    height: 42px;
    border-radius: 50%;
    border: 2px solid var(--border);
    background: transparent;
    font-size: 1.2rem;
    cursor: pointer;
    color: var(--primary);
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition);
}

.btn-check:hover {
    border-color: var(--primary);
    background: var(--primary-light);
}

.btn-check.checked {
    background: var(--success);
    border-color: var(--success);
    color: white;
}

.btn-check:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.btn-check:disabled:hover {
    border-color: var(--border);
    background: transparent;
}

.btn-delete {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 1.1rem;
    cursor: pointer;
    padding: 6px;
    border-radius: 6px;
    transition: color var(--transition), background var(--transition);
    opacity: 0;
}

.habit-card:hover .btn-delete {
    opacity: 1;
}

.btn-delete:hover {
    color: var(--danger);
    background: rgba(225, 112, 85, 0.1);
}

.btn-edit {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 1.05rem;
    cursor: pointer;
    padding: 6px;
    border-radius: 6px;
    transition: color var(--transition), background var(--transition);
    opacity: 0;
}

.habit-card:hover .btn-edit {
    opacity: 1;
}

.btn-edit:hover {
    color: var(--primary);
    background: var(--primary-light);
}

@media (hover: none) {
    .btn-delete,
    .btn-edit {
        opacity: 1;
    }
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 48px 20px;
    color: var(--text-secondary);
}

.empty-icon {
    font-size: 3rem;
    display: block;
    margin-bottom: 12px;
}

/* Plan */
.plan {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.plan-row {
    display: flex;
    align-items: center;
    gap: 10px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 12px 14px;
}

.plan-label {
    width: 150px;
    flex-shrink: 0;
    min-width: 0;
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.plan-name {
    font-weight: 600;
    font-size: 0.85rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.plan-dates {
    font-size: 0.7rem;
    color: var(--text-secondary);
}

.plan-cells {
    display: flex;
    gap: 4px;
    flex: 1;
    overflow-x: auto;
    padding-bottom: 4px;
}

.plan-cells::-webkit-scrollbar {
    height: 6px;
}

.plan-cells::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 3px;
}

.plan-cell {
    min-width: 26px;
    height: 26px;
    flex-shrink: 0;
    border-radius: 6px;
    border: 1px solid var(--border);
    background: var(--bg);
    color: var(--text-secondary);
    font-size: 0.68rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0;
    transition: transform var(--transition);
}

.plan-cell:hover {
    transform: scale(1.15);
}

.plan-cell.done {
    color: #fff;
    border-color: transparent;
    font-weight: 700;
}

.plan-cell.partial {
    color: var(--text);
    border-color: transparent;
}

.plan-cell.today {
    box-shadow: 0 0 0 2px var(--primary);
}

.plan-cell.future {
    border-style: dashed;
}

.plan-cell.week-end {
    margin-right: 8px;
}

/* Modal */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition), visibility var(--transition);
    backdrop-filter: blur(4px);
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 28px;
    width: 90%;
    max-width: 440px;
    box-shadow: var(--shadow-lg);
    transform: translateY(20px);
    transition: transform var(--transition);
}

.modal-overlay.active .modal {
    transform: translateY(0);
}

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

.modal-header h3 {
    font-size: 1.2rem;
    font-weight: 600;
}

.form-group {
    margin-bottom: 18px;
}

.form-group label {
    display: block;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-secondary);
}

.form-group input[type="text"],
.form-group input[type="number"] {
    width: 100%;
    padding: 12px 14px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    background: var(--bg);
    color: var(--text);
    transition: border-color var(--transition);
    outline: none;
}

.form-group input:focus {
    border-color: var(--primary);
}

.emoji-picker {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.emoji-btn {
    width: 40px;
    height: 40px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg);
    font-size: 1.2rem;
    cursor: pointer;
    transition: all var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

.emoji-btn:hover {
    border-color: var(--primary);
    transform: scale(1.1);
}

.emoji-btn.selected {
    border-color: var(--primary);
    background: var(--primary-light);
}

.emoji-input {
    width: 78px;
    height: 40px;
    border: 2px dashed var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg);
    color: var(--text);
    font-size: 1rem;
    text-align: center;
    outline: none;
    transition: border-color var(--transition);
    flex-shrink: 0;
}

.emoji-input:focus {
    border-color: var(--primary);
}

.emoji-input::placeholder {
    font-size: 0.68rem;
    color: var(--text-secondary);
}

.color-picker {
    display: flex;
    gap: 10px;
}

.color-btn {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border: 3px solid transparent;
    cursor: pointer;
    transition: all var(--transition);
}

.color-btn:hover {
    transform: scale(1.15);
}

.color-btn.selected {
    border-color: var(--text);
    box-shadow: 0 0 0 2px var(--surface);
}

.period-picker {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.period-btn {
    border: 2px solid var(--border);
    background: var(--bg);
    border-radius: var(--radius-sm);
    padding: 8px 12px;
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--text);
    cursor: pointer;
    transition: all var(--transition);
}

.period-btn:hover {
    border-color: var(--primary);
}

.period-btn.selected {
    border-color: var(--primary);
    background: var(--primary-light);
    color: var(--primary);
}

/* Responsive */
@media (max-width: 600px) {
    .app {
        padding: 14px;
    }

    .header h1 {
        font-size: 1.3rem;
    }

    .stats-bar {
        grid-template-columns: repeat(2, 1fr);
    }

    .stat-value {
        font-size: 1.3rem;
    }

    .habit-card {
        padding: 14px;
    }

    .habit-emoji {
        font-size: 1.4rem;
        width: 38px;
        height: 38px;
    }

    .plan-label {
        width: 100px;
    }

    .plan-cell {
        min-width: 24px;
        height: 24px;
    }
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.habit-card {
    animation: fadeInUp 0.3s ease forwards;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.2); }
}

.btn-check.checked {
    animation: pulse 0.3s ease;
}

/* Form error */
.form-error {
    color: var(--danger);
    font-size: 0.8rem;
    margin-top: 6px;
}

/* Confirm dialog */
.confirm-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1200;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition), visibility var(--transition);
}

.confirm-overlay.active {
    opacity: 1;
    visibility: visible;
}

.confirm-box {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 24px;
    width: 90%;
    max-width: 340px;
    box-shadow: var(--shadow-lg);
    transform: translateY(20px);
    transition: transform var(--transition);
}

.confirm-overlay.active .confirm-box {
    transform: translateY(0);
}

.confirm-text {
    font-size: 0.95rem;
    line-height: 1.45;
    margin-bottom: 20px;
}

.confirm-actions {
    display: flex;
    gap: 10px;
    justify-content: flex-end;
}

.btn-cancel,
.btn-danger {
    padding: 10px 18px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: background var(--transition);
}

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

.btn-cancel:hover {
    background: var(--surface-hover);
}

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

.btn-danger:hover {
    background: #c95d40;
}

/* Toast */
#toast {
    position: fixed;
    left: 50%;
    bottom: 24px;
    transform: translate(-50%, 20px);
    background: var(--text);
    color: var(--bg);
    padding: 12px 20px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition), transform var(--transition);
    z-index: 1100;
}

#toast.show {
    opacity: 1;
    transform: translate(-50%, 0);
}

/* Focus styles for keyboard users */
.btn-primary:focus-visible,
.btn-icon:focus-visible,
.btn-check:focus-visible,
.btn-edit:focus-visible,
.btn-delete:focus-visible,
.btn-close:focus-visible,
.emoji-btn:focus-visible,
.color-btn:focus-visible,
.period-btn:focus-visible,
.btn-cancel:focus-visible,
.btn-danger:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}