/* Minimalist Black and White Theme */
:root {
    /* Light Theme (Default) */
    --bg-color: #ffffff;
    --text-color: #1a1a1a;
    --surface-color: #f5f5f5;
    --border-color: #e0e0e0;
    --accent-color: #000000;
    --nav-bg: rgba(255, 255, 255, 0.9);
    --nav-border: #eeeeee;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

[data-theme="dark"] {
    /* Dark Theme */
    --bg-color: #000000;
    --text-color: #f5f5f5;
    --surface-color: #111111;
    --border-color: #222222;
    --accent-color: #ffffff;
    --nav-bg: rgba(0, 0, 0, 0.9);
    --nav-border: #1a1a1a;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
}

html {
    height: 100%;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-family);
    line-height: 1.5;
    overflow-x: hidden;
    min-height: 100vh;
    min-height: 100dvh;
}

body.theme-transitioning {
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Utilities */
.hidden {
    display: none !important;
}

#app {
    min-height: 100vh;
    min-height: 100dvh;
    padding-bottom: calc(70px + env(safe-area-inset-bottom)); /* Space for bottom nav */
}

/* Headers */
.top-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: calc(1rem + env(safe-area-inset-top, 0px)) 1rem 1rem 1rem;
    position: sticky;
    top: 0;
    background-color: var(--bg-color);
    z-index: 10;
    border-bottom: 1px solid var(--border-color);
}

.top-nav h1 {
    font-size: 1.25rem;
    font-weight: 600;
}

/* Buttons */
.icon-btn {
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    cursor: pointer;
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    user-select: none;
    transition: transform 0.2s, background-color 0.2s;
}
.icon-btn:active {
    transform: scale(0.95);
}

.btn {
    background-color: var(--accent-color);
    color: var(--bg-color);
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 16px;
    font-weight: 600;
    cursor: pointer;
    font-size: 1rem;
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    user-select: none;
    transition: transform 0.2s, background-color 0.2s;
}
.btn:active {
    transform: scale(0.95);
}

/* Onboarding */
#onboarding {
    min-height: 100vh;
    min-height: 100dvh;
    display: flex;
    flex-direction: column;
    padding: calc(2rem + env(safe-area-inset-top, 0px)) 1rem calc(2rem + env(safe-area-inset-bottom, 0px)) 1rem;
}

.onboarding-content {
    max-width: 400px;
    margin: 0 auto;
    width: 100%;
    display: flex;
    flex-direction: column;
    flex: 1;
}

.onboarding-content h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

.onboarding-content p {
    color: #888;
    margin-bottom: 2rem;
}

input[type="text"] {
    width: 100%;
    padding: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 16px;
    background-color: var(--surface-color);
    color: var(--text-color);
    font-size: 1rem;
    margin-bottom: 1rem;
    outline: none;
}

input[type="text"]:focus {
    border-color: var(--accent-color);
}

.group-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    flex: 1;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    padding-bottom: 3rem; /* Additional padding to scroll completely past the edge */
    -webkit-mask-image: linear-gradient(to bottom, black 90%, transparent 100%);
    mask-image: linear-gradient(to bottom, black 90%, transparent 100%);
}

.group-item {
    padding: 1rem;
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    cursor: pointer;
    font-weight: 500;
    transition: transform 0.1s;
    min-height: 48px;
    display: flex;
    align-items: center;
    user-select: none;
}

.group-item:active {
    transform: scale(0.98);
    will-change: transform;
}

/* Diary Container */
.diary-container {
    padding: 1rem;
    max-width: 600px;
    margin: 0 auto;
    contain: content;
}

.diary-day {
    margin-bottom: 2rem;
}

.diary-day h2 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    border-bottom: 2px solid var(--accent-color);
    display: inline-block;
    padding-bottom: 0.2rem;
}

.date-badge {
    color: var(--text-color);
    opacity: 0.6;
    font-weight: 500;
    font-size: 0.85em;
    margin-left: 6px;
}

.is-today h2 {
    color: var(--bg-color);
    background-color: var(--text-color);
    border-bottom: none;
    padding: 0.3rem 0.8rem;
    border-radius: 12px;
}

.today-badge {
    font-size: 0.65rem;
    background: var(--accent-color);
    color: var(--bg-color);
    padding: 2px 6px;
    border-radius: 6px;
    margin-left: 0.5rem;
    vertical-align: text-top;
    font-weight: 800;
}

.diary-item {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 1rem;
    margin-bottom: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    contain: layout style;
}

.diary-item.substitution {
    border-color: #f59e0b; /* Amber/Orange standard color for warnings/changes */
    background: linear-gradient(145deg, rgba(245, 158, 11, 0.05) 0%, transparent 100%);
}

.badge-substitution {
    display: inline-block;
    background-color: #f59e0b;
    color: #fff;
    font-size: 0.7em;
    font-weight: 800;
    padding: 2px 6px;
    border-radius: 6px;
    margin-right: 6px;
    vertical-align: middle;
    text-transform: uppercase;
}

.diary-item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.9rem;
    color: #888;
}

.diary-item-number {
    font-weight: 700;
    color: var(--accent-color);
    background: var(--bg-color);
    padding: 2px 10px;
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.diary-item-time {
    font-size: 0.8rem;
    color: #888;
    background: var(--surface-color);
    padding: 2px 10px;
    border-radius: 12px;
    border: 1px dashed var(--border-color);
}

.diary-item-subject {
    font-size: 1.1rem;
    font-weight: 600;
}

.diary-item-teacher {
    font-size: 0.9rem;
    color: #666;
}

.homework-btn {
    align-self: flex-start;
    background: transparent;
    border: 1px dashed var(--border-color);
    color: var(--text-color);
    padding: 0.5rem 1rem;
    border-radius: 12px;
    font-size: 0.8rem;
    cursor: pointer;
    margin-top: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    min-height: 44px;
    user-select: none;
    transition: transform 0.2s, background-color 0.2s;
}
.homework-btn:active {
    transform: scale(0.95);
}

/* Settings and Homework Empty States */
.settings-container, .homework-container {
    padding: 1rem;
    max-width: 600px;
    margin: 0 auto;
}

.setting-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--border-color);
    min-height: 48px;
}

.empty-state {
    text-align: center;
    color: #888;
    margin-top: 3rem;
}

.empty-state-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 3rem 1rem;
    color: #888;
}

.empty-state-icon {
    opacity: 0.2;
    margin-bottom: 1rem;
    color: var(--text-color);
}

.empty-state-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 0.5rem;
}

.empty-state-desc {
    font-size: 0.9rem;
    max-width: 280px;
    line-height: 1.4;
}

/* Toggle Switch */
.switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 28px;
}
.switch input { 
    opacity: 0;
    width: 0;
    height: 0;
}
.slider {
    position: absolute;
    cursor: pointer;
    top: 0; left: 0; right: 0; bottom: 0;
    background-color: var(--border-color);
    transition: .4s;
    border-radius: 34px;
}
.slider:before {
    position: absolute;
    content: "";
    height: 20px;
    width: 20px;
    left: 4px;
    bottom: 4px;
    background-color: var(--bg-color);
    transition: .4s;
    border-radius: 50%;
}
input:checked + .slider {
    background-color: var(--accent-color);
}
input:checked + .slider:before {
    transform: translateX(22px);
}

/* Bottom Navigation */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: calc(65px + env(safe-area-inset-bottom, 0px));
    padding-bottom: env(safe-area-inset-bottom, 0px);
    background-color: var(--nav-bg);
    backdrop-filter: blur(10px);
    border-top: 1px solid var(--nav-border);
    display: flex;
    justify-content: space-around;
    align-items: center;
    z-index: 100;
    user-select: none;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-decoration: none;
    color: #888;
    gap: 4px;
    width: 30%;
    height: 65px;
    transition: color 0.2s, transform 0.2s;
}

.nav-item:active {
    transform: scale(0.92);
}

.nav-item svg {
    opacity: 0.7;
}

.nav-item span {
    font-size: 0.7rem;
    font-weight: 500;
}

.nav-item.active {
    color: var(--accent-color);
}

.nav-item.active svg {
    opacity: 1;
}

/* Utility to hide scrollbar but keep functionality */
::-webkit-scrollbar {
    width: 0px;
    background: transparent;
}

/* ===== Modal (Bottom Sheet) ===== */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.4);
    z-index: 200;
    display: flex;
    align-items: flex-end;
    justify-content: center;
    animation: fadeIn 0.2s ease;
}

.modal-sheet {
    background-color: var(--bg-color);
    width: 100%;
    max-width: 500px;
    border-radius: 20px 20px 0 0;
    padding: 1rem 1.25rem calc(1.5rem + env(safe-area-inset-bottom, 0px)) 1.25rem;
    animation: slideUp 0.3s ease;
}

.modal-handle {
    width: 40px;
    height: 4px;
    background: var(--border-color);
    border-radius: 2px;
    margin: 0 auto 1rem auto;
}

.modal-sheet h2 {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
}

.modal-subject {
    font-size: 0.85rem;
    color: #888;
    margin-bottom: 1rem;
}

.modal-sheet textarea {
    width: 100%;
    padding: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 16px;
    background-color: var(--surface-color);
    color: var(--text-color);
    font-size: 1rem;
    font-family: inherit;
    outline: none;
    resize: none;
    margin-bottom: 1rem;
    -webkit-overflow-scrolling: touch;
}

.modal-sheet textarea:focus {
    border-color: var(--accent-color);
}

.modal-actions {
    display: flex;
    gap: 0.75rem;
}

.modal-btn-cancel,
.modal-btn-save {
    flex: 1;
    padding: 0.75rem;
    border-radius: 16px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    min-height: 48px;
    border: none;
    user-select: none;
    transition: transform 0.2s;
}

.modal-btn-cancel:active,
.modal-btn-save:active {
    transform: scale(0.95);
}

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

.modal-btn-save {
    background: var(--accent-color);
    color: var(--bg-color);
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideUp {
    from { transform: translateY(100%); }
    to { transform: translateY(0); }
}

/* ===== Saved Homework on Lesson Card ===== */
.hw-saved {
    border-left: 3px solid var(--accent-color);
    padding: 0.4rem 0.75rem;
    margin-top: 0.25rem;
    font-size: 0.85rem;
    line-height: 1.4;
    white-space: pre-wrap;
    word-break: break-word;
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 0.5rem;
}

.hw-saved-header {
    display: none;
}

.hw-delete-btn {
    background: none;
    border: none;
    color: #999;
    cursor: pointer;
    padding: 2px;
    display: flex;
    align-items: center;
    min-height: 28px;
    min-width: 28px;
    justify-content: center;
    flex-shrink: 0;
}

/* ===== Homework Tab Cards ===== */
.hw-card {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 1rem;
    margin-bottom: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.hw-card-subject {
    font-size: 1.05rem;
    font-weight: 600;
}

.hw-card-meta {
    font-size: 0.8rem;
    color: #888;
}

.hw-card-text {
    font-size: 0.95rem;
    line-height: 1.4;
    white-space: pre-wrap;
    word-break: break-word;
    margin-top: 0.25rem;
}

.hw-card-actions {
    display: flex;
    gap: 0.5rem;
    margin-top: 0.5rem;
}

.hw-card-actions button {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 0.4rem 1rem;
    border-radius: 12px;
    font-size: 0.8rem;
    cursor: pointer;
    min-height: 36px;
    display: flex;
    align-items: center;
    gap: 0.35rem;
    user-select: none;
    transition: transform 0.2s;
}

.hw-card-actions button:active {
    transform: scale(0.95);
}

.hw-card-actions .hw-delete {
    color: #cc0000;
    border-color: #cc000040;
}

/* Notification Prompt Banner */
.notif-prompt {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 16px;
    margin: 8px 16px 0;
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 14px;
    gap: 12px;
}
.notif-prompt-text {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.9rem;
    font-weight: 500;
}
.notif-prompt-icon {
    font-size: 1.3rem;
}
.notif-prompt-actions {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-shrink: 0;
}
.notif-prompt-enable {
    background: var(--accent-color);
    color: var(--bg-color);
    border: none;
    padding: 6px 14px;
    border-radius: 10px;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    white-space: nowrap;
}
.notif-prompt-enable:active {
    opacity: 0.7;
}
.notif-prompt-dismiss {
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 1.3rem;
    cursor: pointer;
    padding: 0 4px;
    opacity: 0.4;
}
.notif-prompt-dismiss:active {
    opacity: 0.8;
}