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

:root {
    --bg: #ffffff;
    --bg-secondary: #f5f5f5;
    --text: #1a1a1a;
    --text-muted: #888888;
    --border: #e0e0e0;
    --accent: #2563eb;
    --accent-hover: #1d4ed8;
    --danger: #dc2626;
    --danger-hover: #b91c1c;
    --completed-text: #aaaaaa;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #1a1a1a;
        --bg-secondary: #2a2a2a;
        --text: #e5e5e5;
        --text-muted: #777777;
        --border: #3a3a3a;
        --accent: #3b82f6;
        --accent-hover: #60a5fa;
        --danger: #ef4444;
        --danger-hover: #f87171;
        --completed-text: #555555;
        --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
    }
}

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

/* Login */
.login-container {
    max-width: 360px;
    margin: 20vh auto 0;
    padding: 0 1rem;
    text-align: center;
}

.login-container h1 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
}

.login-container form {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.login-container input {
    padding: 0.75rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--bg-secondary);
    color: var(--text);
    font-size: 1rem;
}

.login-container button {
    padding: 0.75rem;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
}

.login-container button:hover {
    background: var(--accent-hover);
}

.error {
    color: var(--danger);
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

/* Header */
header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 600px;
    margin: 0 auto;
    padding: 1rem;
    border-bottom: 1px solid var(--border);
}

header h1 {
    font-size: 1.25rem;
    font-weight: 700;
}

.header-actions {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

.btn-primary {
    padding: 0.5rem 1rem;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 6px;
    font-size: 0.875rem;
    cursor: pointer;
    font-weight: 500;
}

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

.btn-secondary {
    padding: 0.5rem 1rem;
    background: var(--bg-secondary);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 0.875rem;
    cursor: pointer;
}

.logout-form {
    display: inline;
}

.btn-logout {
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 0.8rem;
    cursor: pointer;
    padding: 0;
}

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

/* Main */
main {
    max-width: 600px;
    margin: 0 auto;
    padding: 0.5rem 1rem 2rem;
}

/* Add form */
.add-form {
    padding: 1rem;
    margin: 0.5rem 0;
    background: var(--bg-secondary);
    border-radius: 8px;
    border: 1px solid var(--border);
}

.add-form input[type="text"] {
    width: 100%;
    padding: 0.625rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--bg);
    color: var(--text);
    font-size: 1rem;
    margin-bottom: 0.75rem;
}

.schedule-options {
    display: flex;
    gap: 1rem;
    margin-bottom: 0.75rem;
    font-size: 0.875rem;
}

.schedule-options label {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    cursor: pointer;
}

.form-buttons {
    display: flex;
    gap: 0.5rem;
}

.hidden {
    display: none !important;
}

/* Quick add */
.quick-add {
    width: 100%;
    padding: 0.625rem 0.75rem;
    margin: 0.75rem 0 0.25rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--bg-secondary);
    color: var(--text);
    font-size: 1rem;
}

.quick-add::placeholder {
    color: var(--text-muted);
}

.quick-add:focus {
    outline: none;
    border-color: var(--accent);
}

/* Task list */
.task-list {
    min-height: 2px;
}

.task-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 0.5rem;
    border-bottom: 1px solid var(--border);
    background: var(--bg);
    transition: opacity 0.2s, background 0.15s;
}

.task-item:last-child {
    border-bottom: none;
}

.task-item.sortable-ghost {
    opacity: 0.4;
    background: var(--bg-secondary);
}

.task-item.sortable-drag {
    box-shadow: var(--shadow);
    border-radius: 6px;
}

.task-checkbox {
    width: 22px;
    height: 22px;
    flex-shrink: 0;
    cursor: pointer;
    accent-color: var(--accent);
}

.task-title {
    flex: 1;
    font-size: 1rem;
    line-height: 1.4;
    min-width: 0;
    word-break: break-word;
}

.task-schedule {
    font-size: 0.7rem;
    color: var(--text-muted);
    flex-shrink: 0;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

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

.task-item.completed .task-schedule {
    color: var(--completed-text);
}

.drag-handle {
    cursor: grab;
    color: var(--text-muted);
    font-size: 1.1rem;
    flex-shrink: 0;
    padding: 0 0.25rem;
    user-select: none;
    -webkit-user-select: none;
}

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

.btn-delete {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    font-size: 1rem;
    padding: 0.25rem;
    flex-shrink: 0;
    line-height: 1;
    border-radius: 4px;
}

.btn-delete:hover {
    color: var(--danger);
    background: var(--bg-secondary);
}

/* Edit mode */
.task-edit-input {
    flex: 1;
    padding: 0.375rem 0.5rem;
    border: 1px solid var(--accent);
    border-radius: 4px;
    background: var(--bg);
    color: var(--text);
    font-size: 1rem;
    outline: none;
}

/* Separator */
.separator {
    text-align: center;
    padding: 0.75rem 0 0.25rem;
    color: var(--text-muted);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.separator span {
    position: relative;
    padding: 0 0.75rem;
    background: var(--bg);
}

.separator::before {
    content: "";
    display: block;
    position: relative;
    top: 0.6em;
    border-top: 1px solid var(--border);
}

/* Empty state */
.empty-state {
    text-align: center;
    color: var(--text-muted);
    padding: 3rem 1rem;
    font-size: 0.95rem;
}

/* Mobile */
@media (max-width: 768px) {
    header {
        padding: 0.75rem 1rem;
    }

    .task-item {
        padding: 1rem 0.5rem;
        gap: 0.625rem;
    }

    .task-checkbox {
        width: 26px;
        height: 26px;
    }

    .drag-handle {
        font-size: 1.3rem;
        padding: 0.5rem 0.25rem;
    }

    .btn-delete {
        font-size: 1.15rem;
        padding: 0.5rem;
    }

    .schedule-options {
        flex-wrap: wrap;
        gap: 0.75rem;
    }
}