@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;500;600;700;800&family=Space+Grotesk:wght@500;700&display=swap');

:root {
    --bg-base: #090d16;
    --bg-card: #131a26;
    --bg-card-hover: #1b2536;
    --bg-input: #0e1320;
    --color-primary: #0ea5e9;
    --color-primary-rgb: 14, 165, 233;
    --color-primary-hover: #0284c7;
    --color-paid: #10b981;
    --color-paid-rgb: 16, 185, 129;
    --color-unpaid: #f43f5e;
    --color-unpaid-rgb: 244, 63, 94;
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --text-light: #64748b;
    --border-color: #1e293b;
    --border-highlight: #334155;
    --shadow-main: 0 4px 20px rgba(0, 0, 0, 0.25);
    --font-sans: 'Outfit', sans-serif;
    --font-heading: 'Space Grotesk', sans-serif;
}

[data-theme="light"] {
    --bg-base: #f8fafc;
    --bg-card: #ffffff;
    --bg-card-hover: #f1f5f9;
    --bg-input: #f8fafc;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --text-light: #94a3b8;
    --border-color: #e2e8f0;
    --border-highlight: #cbd5e1;
    --shadow-main: 0 4px 15px rgba(0, 0, 0, 0.05);
}

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

body {
    font-family: var(--font-sans);
    background-color: var(--bg-base);
    color: var(--text-main);
    line-height: 1.5;
    transition: background-color 0.3s ease, color 0.3s ease;
    padding-bottom: 80px; /* Space for sticky bar or extra padding */
}

.app-container {
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
    padding: 1rem;
}

/* Header */
.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.25rem;
    padding: 0.5rem 0;
}

.app-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-icon {
    width: 42px;
    height: 42px;
    background: linear-gradient(135deg, var(--color-primary), var(--color-paid));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #ffffff;
    font-weight: 800;
    font-family: var(--font-heading);
    font-size: 1.4rem;
    box-shadow: 0 4px 12px rgba(14, 165, 233, 0.3);
}

.logo-text h1 {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.logo-text p {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 500;
}

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

.icon-btn {
    width: 40px;
    height: 40px;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-card);
    color: var(--text-main);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 1.1rem;
    transition: all 0.2s ease;
}

.icon-btn:hover {
    background-color: var(--bg-card-hover);
    border-color: var(--border-highlight);
}

.icon-btn:active {
    transform: scale(0.95);
}

/* Stats Dashboard */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.75rem;
    margin-bottom: 1.25rem;
}

.stat-card-full {
    grid-column: span 2;
    background: linear-gradient(135deg, rgba(14, 165, 233, 0.1), rgba(16, 185, 129, 0.05));
    border: 1px solid rgba(14, 165, 233, 0.2);
}

.stat-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1rem;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    box-shadow: var(--shadow-main);
}

.stat-label {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.02em;
    margin-bottom: 0.25rem;
}

.stat-value {
    font-family: var(--font-heading);
    font-size: 1.4rem;
    font-weight: 700;
}

.stat-sub {
    font-size: 0.75rem;
    color: var(--text-light);
    margin-top: 0.25rem;
    display: flex;
    justify-content: space-between;
}

/* Month Selector */
.month-selector-wrapper {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 14px;
    padding: 0.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.25rem;
    box-shadow: var(--shadow-main);
}

.month-display {
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 0.95rem;
    color: var(--color-primary);
}

/* Grade Tab Selectors */
.grade-tabs {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.tab-btn {
    padding: 0.75rem 0.5rem;
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 0.9rem;
    border: 1px solid var(--border-color);
    background-color: var(--bg-card);
    color: var(--text-muted);
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
}

.tab-btn.active {
    background: linear-gradient(135deg, var(--color-primary), #0284c7);
    color: #ffffff;
    border-color: transparent;
    box-shadow: 0 4px 12px rgba(14, 165, 233, 0.25);
}

.tab-btn:active {
    transform: scale(0.96);
}

/* Search and Filters */
.search-filter-wrapper {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.search-input-container {
    position: relative;
    flex-grow: 1;
}

.search-input {
    width: 100%;
    height: 44px;
    padding: 0 1rem 0 2.5rem;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-input);
    color: var(--text-main);
    font-family: inherit;
    font-size: 0.9rem;
    outline: none;
    transition: border-color 0.2s ease;
}

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

.search-icon {
    position: absolute;
    left: 0.9rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    pointer-events: none;
}

/* Class filter tags */
.class-tags-scroll {
    display: flex;
    gap: 0.5rem;
    overflow-x: auto;
    padding-bottom: 0.5rem;
    margin-bottom: 1rem;
    scrollbar-width: none; /* Firefox */
}

.class-tags-scroll::-webkit-scrollbar {
    display: none; /* Safari/Chrome */
}

.class-tag {
    flex-shrink: 0;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    cursor: pointer;
    transition: all 0.2s ease;
}

.class-tag.active {
    background-color: rgba(14, 165, 233, 0.15);
    border-color: var(--color-primary);
    color: var(--color-primary);
}

/* Student List Grid */
.student-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.student-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 0.85rem 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow-main);
    transition: transform 0.2s ease, border-color 0.2s ease;
}

.student-card:hover {
    border-color: var(--border-highlight);
}

.student-info {
    flex-grow: 1;
    padding-right: 1rem;
}

.student-name-row {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.15rem;
}

.student-name {
    font-size: 0.95rem;
    font-weight: 700;
}

.student-class-badge {
    font-size: 0.7rem;
    background-color: var(--bg-input);
    border: 1px solid var(--border-color);
    color: var(--text-muted);
    padding: 0.1rem 0.4rem;
    border-radius: 6px;
    font-weight: 600;
}

.student-fee {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 500;
}

/* Big Status Button */
.status-toggle-btn {
    min-width: 105px;
    height: 44px;
    border-radius: 10px;
    border: none;
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 0.8rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.35rem;
    transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    color: #ffffff;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.status-toggle-btn.unpaid {
    background-color: var(--color-unpaid);
    box-shadow: 0 4px 10px rgba(244, 63, 94, 0.25);
}

.status-toggle-btn.paid {
    background-color: var(--color-paid);
    box-shadow: 0 4px 10px rgba(16, 185, 129, 0.25);
}

.status-toggle-btn:active {
    transform: scale(0.92);
}

/* Section Title & Options bar */
.section-title-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
    margin-top: 0.5rem;
}

.section-title {
    font-family: var(--font-heading);
    font-size: 1rem;
    font-weight: 700;
}

.section-actions {
    display: flex;
    gap: 0.5rem;
}

/* Button UI Components */
.btn-action {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 0.85rem;
    border-radius: 10px;
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    font-size: 0.8rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn-action:hover {
    background-color: var(--bg-card-hover);
    border-color: var(--border-highlight);
}

.btn-action.active {
    background-color: rgba(244, 63, 94, 0.15);
    border-color: var(--color-unpaid);
    color: var(--color-unpaid);
}

.btn-action:active {
    transform: scale(0.96);
}

/* Modal UI / Admin panel overlay */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(9, 13, 22, 0.8);
    backdrop-filter: blur(8px);
    z-index: 1000;
    display: flex;
    justify-content: center;
    align-items: flex-end; /* Slide up from bottom on mobile */
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
}

.modal-overlay.active {
    opacity: 1;
    pointer-events: auto;
}

.modal-content {
    width: 100%;
    max-width: 500px;
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-top-left-radius: 24px;
    border-top-right-radius: 24px;
    padding: 1.5rem;
    box-shadow: 0 -10px 25px rgba(0,0,0,0.5);
    transform: translateY(100%);
    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    max-height: 90vh;
    display: flex;
    flex-direction: column;
}

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

@media (min-width: 600px) {
    .modal-overlay {
        align-items: center; /* Center on desktop */
    }
    .modal-content {
        border-radius: 20px;
        max-height: 80vh;
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.25rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

.modal-title {
    font-family: var(--font-heading);
    font-size: 1.15rem;
    font-weight: 700;
}

.modal-body {
    overflow-y: auto;
    flex-grow: 1;
    padding-bottom: 1rem;
}

/* Form controls */
.form-group {
    margin-bottom: 1rem;
}

.form-label {
    display: block;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    margin-bottom: 0.4rem;
}

.form-control {
    width: 100%;
    height: 44px;
    padding: 0 1rem;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-input);
    color: var(--text-main);
    font-family: inherit;
    font-size: 0.9rem;
    outline: none;
    transition: border-color 0.2s ease;
}

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

.form-row-2 {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.75rem;
}

.btn-submit {
    width: 100%;
    height: 48px;
    background: linear-gradient(135deg, var(--color-primary), var(--color-primary-hover));
    color: #ffffff;
    border: none;
    border-radius: 12px;
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 0.95rem;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(14, 165, 233, 0.3);
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.btn-submit:active {
    transform: scale(0.96);
}

/* Toast Notifications */
.toast-container {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background-color: #1e293b;
    border: 1px solid var(--border-highlight);
    color: #ffffff;
    padding: 0.75rem 1.5rem;
    border-radius: 30px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.3);
    font-size: 0.85rem;
    font-weight: 600;
    z-index: 2000;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    pointer-events: none;
    opacity: 0;
    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.3s ease;
}

.toast-container.active {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

/* Student Admin List inside Settings */
.admin-student-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-top: 1rem;
    max-height: 250px;
    overflow-y: auto;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 0.5rem;
    background-color: var(--bg-input);
}

.admin-student-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}

.admin-student-row:last-child {
    border-bottom: none;
}

.admin-student-info {
    font-size: 0.8rem;
}

.admin-student-actions {
    display: flex;
    gap: 0.25rem;
}

.icon-action-btn {
    width: 28px;
    height: 28px;
    border-radius: 6px;
    border: none;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 0.8rem;
    color: #ffffff;
}

.icon-action-btn.edit {
    background-color: var(--color-primary);
}

.icon-action-btn.delete {
    background-color: var(--color-unpaid);
}

.icon-action-btn:active {
    transform: scale(0.9);
}

.empty-list {
    text-align: center;
    padding: 2.5rem 1rem;
    color: var(--text-muted);
    font-size: 0.85rem;
}

.empty-list svg {
    margin-bottom: 0.5rem;
    color: var(--text-light);
}

/* Responsive tweaks */
@media (max-width: 360px) {
    .stats-grid {
        grid-template-columns: 1fr;
    }
    .stat-card-full {
        grid-column: span 1;
    }
}

/* Chế độ chỉnh sửa (Lock/Unlock) */
#lockToggleBtn.locked {
    border-color: rgba(244, 63, 94, 0.35) !important;
    background-color: rgba(244, 63, 94, 0.08) !important;
    color: var(--color-unpaid) !important;
    box-shadow: 0 0 10px rgba(244, 63, 94, 0.15);
}

#lockToggleBtn.unlocked {
    border-color: rgba(16, 185, 129, 0.35) !important;
    background-color: rgba(16, 185, 129, 0.08) !important;
    color: var(--color-paid) !important;
    box-shadow: 0 0 10px rgba(16, 185, 129, 0.15);
}

[data-locked="true"] .status-toggle-btn {
    cursor: not-allowed !important;
    opacity: 0.85;
}

[data-locked="true"] #openSettingsBtn {
    cursor: not-allowed !important;
    opacity: 0.5;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    20%, 60% { transform: translateX(-6px); }
    40%, 80% { transform: translateX(6px); }
}

.shake-error {
    animation: shake 0.4s ease-in-out;
    border-color: var(--color-unpaid) !important;
    box-shadow: 0 0 10px rgba(244, 63, 94, 0.2) !important;
}

/* Thống kê doanh thu chi tiết */
.revenue-split-row {
    display: flex;
    justify-content: space-between;
    margin-top: 0.5rem;
    gap: 0.75rem;
}

.rev-item {
    display: flex;
    flex-direction: column;
    flex: 1;
}

.rev-label {
    font-size: 0.65rem;
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
    margin-bottom: 0.15rem;
    letter-spacing: 0.02em;
}

.rev-value {
    font-family: var(--font-heading);
    font-size: 1.15rem;
    font-weight: 700;
}

.color-paid {
    color: var(--color-paid);
}

.color-unpaid {
    color: var(--color-unpaid);
}