:root {
    --bg-body: #f4f8f8;
    --bg-card: #ffffff;
    --pill-bg: #d9ebeb;
    --color-heading: #023a44;
    --color-text: #132e35;
    --color-dim: #49636a;
    --color-done: #92abb1;
    --accent: #023a44;
    --teal: #5bc0be;
    --teal-bg: #e6f4f5;
    --border: #bce0e1;
    --border-dark: #023a44;
    --radius: 4px;
    --radius-sm: 2px;
    --transition: all 0.15s ease-in-out;
    --shadow: 0 2px 8px -2px rgba(2, 58, 68, 0.08), 0 1px 4px -1px rgba(2, 58, 68, 0.04);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", Roboto, sans-serif;
    background: var(--bg-body);
    padding: 0 20px 80px 20px;
    max-width: 720px;
    margin: auto;
    color: var(--color-text);
    -webkit-font-smoothing: antialiased;
}

.sticky-header {
    position: sticky;
    top: 0;
    background: rgba(244, 248, 248, 0.9);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    z-index: 100;
    padding: 24px 0 16px 0;
    margin-bottom: 24px;
    border-bottom: 1px solid transparent;
    transition: border-bottom-color 0.2s ease;
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

h1 {
    margin: 0;
    font-size: 26px;
    font-weight: 700;
    letter-spacing: -0.03em;
    color: var(--color-heading);
}

.action-group {
    display: flex;
    gap: 8px;
}

.utility-btn {
    background: var(--bg-card);
    color: var(--color-dim);
    border: 1px solid var(--border);
    padding: 6px 14px;
    border-radius: var(--radius-sm);
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.02);
}

.utility-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--teal-bg);
}

.utility-btn.primary {
    background: var(--teal);
    color: var(--color-heading);
    border-color: var(--teal);
}

.utility-btn.primary:hover {
    background: #49b2b0;
    border-color: #49b2b0;
    color: var(--color-heading);
}

#file-input-hidden {
    display: none;
}

.controls {
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
    background: var(--pill-bg);
    padding: 4px;
    border-radius: var(--radius);
    width: fit-content;
    border: 1px solid rgba(2, 58, 68, 0.08);
}

.controls label {
    display: inline-flex;
    align-items: center;
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    padding: 6px 14px;
    border-radius: var(--radius-sm);
    color: var(--color-dim);
    transition: var(--transition);
    user-select: none;
}

.controls label:has(input:checked) {
    background: var(--bg-card);
    color: var(--accent);
    box-shadow: 0 1px 3px rgba(2, 58, 68, 0.06);
}

.controls input[type="checkbox"] {
    display: none;
}

.card {
    background: var(--bg-card);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 24px;
    border: 1px solid var(--border);
    overflow: hidden;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
    border-color: var(--teal);
    box-shadow: 0 4px 12px -2px rgba(2, 58, 68, 0.08);
}

.card-header {
    padding: 20px 24px 14px 24px;
    background: var(--teal-bg);
    border-bottom: 1px solid rgba(2, 58, 68, 0.04);
}

h2 {
    font-size: 16px;
    margin: 0;
    color: var(--color-heading);
    font-weight: 700;
    letter-spacing: -0.01em;
}

.sub-group-title {
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin: 24px 24px 8px 24px;
    color: var(--teal);
    font-weight: 700;
}

.item-list {
    display: flex;
    flex-direction: column;
}

.item-wrapper {
    border-bottom: 1px solid rgba(217, 235, 235, 0.6);
    transition: var(--transition);
}

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

.item-wrapper:hover {
    background: rgba(2, 58, 68, 0.01);
}

.item-row {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    padding: 14px 24px;
    gap: 12px;
}

.item-label {
    display: flex;
    align-items: flex-start;
    gap: 14px;
    cursor: pointer;
    flex-grow: 1;
    user-select: none;
}

.custom-checkbox {
    position: relative;
    width: 18px;
    height: 18px;
    border: 1.5px solid var(--border-dark);
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    transition: background 0.1s ease, border-color 0.1s ease, transform 0.05s ease;
    flex-shrink: 0;
    margin-top: 1px;
}

.item-label:active .custom-checkbox {
    transform: scale(0.95);
}

.item-label input[type="checkbox"] {
    display: none;
}

.item-label input[type="checkbox"]:checked + .custom-checkbox {
    background: var(--accent);
    border-color: var(--accent);
}

.item-label input[type="checkbox"]:checked + .custom-checkbox::after {
    content: "";
    position: absolute;
    left: 5px;
    top: 2px;
    width: 4px;
    height: 8px;
    border: solid #ffffff;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

.item-label span {
    font-size: 14px;
    line-height: 1.45;
    color: var(--color-text);
    font-weight: 500;
    transition: var(--transition);
}

.item-label input[type="checkbox"]:checked ~ span {
    text-decoration: line-through;
    color: var(--color-done);
}

.expand-trigger {
    background: none;
    border: none;
    padding: 4px 8px;
    cursor: pointer;
    color: var(--color-done);
    font-size: 12px;
    transition: var(--transition);
    border-radius: var(--radius-sm);
    margin-top: -2px;
}

.expand-trigger:hover {
    background: var(--teal-bg);
    color: var(--accent);
}

.item-wrapper.open .expand-trigger {
    transform: rotate(90deg);
    color: var(--teal);
}

.item-details {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.2s ease-in-out;
    background: rgba(2, 58, 68, 0.005);
}

.item-wrapper.open .item-details {
    max-height: 800px;
}

.item-details-inner {
    padding: 0 24px 16px 56px;
    font-size: 13px;
    line-height: 1.5;
    color: var(--color-dim);
    max-width: 65ch;
}

.link-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.link-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    color: var(--color-dim);
    text-decoration: none;
    font-size: 13px;
    font-weight: 600;
    padding: 14px 24px;
    border-bottom: 1px solid rgba(217, 235, 235, 0.6);
    transition: var(--transition);
}

.link-list li:last-child .link-item {
    border-bottom: none;
}

.link-item:hover {
    color: var(--accent);
    background: var(--teal-bg);
}

.link-text-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

.link-icon {
    font-size: 13px;
    color: var(--color-done);
}

.link-arrow {
    font-size: 12px;
    color: var(--color-done);
    opacity: 0;
    transform: translateX(-4px);
    transition: var(--transition);
}

.link-item:hover .link-arrow {
    opacity: 1;
    transform: translateX(0);
    color: var(--teal);
}

.empty-placeholder {
    padding: 60px 40px;
    text-align: center;
    border: 2px dashed var(--border);
    background: var(--bg-card);
    color: var(--color-dim);
    margin-top: 40px;
    border-radius: var(--radius);
}

.empty-placeholder h3 {
    margin: 0 0 10px 0;
    color: var(--color-heading);
    font-size: 18px;
}

.empty-placeholder p {
    font-size: 14px;
    margin: 0 0 20px 0;
}