:root {
    /* Color Palette - Premium Dark Mode */
    --bg-dark: #0f172a;
    --bg-panel: #1e293b;
    --bg-panel-hover: #334155;
    
    --primary: #3b82f6; /* Blue */
    --primary-glow: rgba(59, 130, 246, 0.5);
    
    --accent-tarih: #ef4444; /* Red */
    --accent-cografya: #10b981; /* Green */
    --accent-vatandaslik: #8b5cf6; /* Purple */
    --accent-turkce: #f59e0b; /* Orange */
    --accent-matematik: #06b6d4; /* Cyan */
    
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    
    --border-color: rgba(255, 255, 255, 0.1);
    --border-radius: 16px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* Glassmorphism Defaults */
    --glass-bg: rgba(30, 41, 59, 0.7);
    --glass-blur: blur(12px);
}

/* Ocean Theme */
body[data-theme="ocean"] {
    --bg-dark: #083344;
    --bg-panel: rgba(22, 78, 99, 0.6);
    --bg-panel-hover: rgba(22, 78, 99, 0.9);
    --glass-bg: rgba(22, 78, 99, 0.5);
    --border-color: rgba(165, 243, 252, 0.2);
}

/* Cyber Theme */
body[data-theme="cyber"] {
    --bg-dark: #2e0219;
    --bg-panel: rgba(80, 7, 36, 0.6);
    --bg-panel-hover: rgba(159, 18, 57, 0.8);
    --glass-bg: rgba(80, 7, 36, 0.5);
    --border-color: rgba(244, 63, 94, 0.2);
    --primary: #f43f5e;
    --primary-glow: rgba(244, 63, 94, 0.6);
    --accent-cografya: #06b6d4;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-main);
    display: flex;
    height: 100vh;
    overflow: hidden;
}

h1, h2, h3 {
    font-family: 'Outfit', sans-serif;
}

/* Scrollbar styling */
::-webkit-scrollbar {
    width: 8px;
}
::-webkit-scrollbar-track {
    background: var(--bg-dark);
}
::-webkit-scrollbar-thumb {
    background: var(--bg-panel-hover);
    border-radius: 4px;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background-color: var(--bg-panel);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    padding: 20px 0;
    z-index: 10;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 0 24px 30px;
    font-size: 24px;
    font-weight: 800;
    color: var(--primary);
    font-family: 'Outfit', sans-serif;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 20px;
}

.logo i {
    font-size: 28px;
    filter: drop-shadow(0 0 8px var(--primary-glow));
}

.nav-links {
    list-style: none;
    flex: 1;
}

.nav-links li {
    padding: 16px 24px;
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--text-muted);
    cursor: pointer;
    transition: var(--transition);
    font-size: 15px;
    font-weight: 500;
    border-left: 3px solid transparent;
}

.nav-links li:hover {
    background-color: var(--bg-panel-hover);
    color: var(--text-main);
}

.nav-links li.active {
    background-color: rgba(59, 130, 246, 0.1);
    color: var(--primary);
    border-left-color: var(--primary);
}

.nav-links li i {
    width: 20px;
    text-align: center;
}

.exam-countdown {
    margin: 20px 24px;
    padding: 16px;
    background: linear-gradient(135deg, rgba(239, 68, 68, 0.1), rgba(239, 68, 68, 0.05));
    border: 1px solid rgba(239, 68, 68, 0.2);
    border-radius: var(--border-radius);
    text-align: center;
}

.countdown-label {
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
    margin-bottom: 5px;
}

.countdown-value {
    font-size: 24px;
    font-weight: 700;
    color: var(--accent-tarih);
    font-family: 'Outfit', sans-serif;
}

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.topbar {
    height: 80px;
    padding: 0 40px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid var(--border-color);
    background-color: rgba(30, 41, 59, 0.8);
    backdrop-filter: blur(10px);
    z-index: 5;
}

#page-title {
    font-size: 22px;
    font-weight: 600;
}

.user-stats {
    display: flex;
    align-items: center;
    gap: 20px;
}

.stat-badge {
    background-color: var(--bg-panel);
    padding: 8px 16px;
    border-radius: 20px;
    display: flex;
    align-items: center;
    gap: 8px;
    border: 1px solid var(--border-color);
    font-weight: 600;
}

.stat-badge i {
    color: var(--primary);
}

.btn-primary {
    background-color: var(--primary);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 8px;
    box-shadow: 0 4px 12px var(--primary-glow);
}

.btn-primary:hover {
    background-color: #2563eb;
    transform: translateY(-2px);
}

/* View Container */
#view-container {
    flex: 1;
    overflow-y: auto;
    padding: 40px;
}

/* Dashboard View */
.view-section {
    display: none;
    animation: fadeIn 0.4s ease-out;
}

.view-section.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Days Grid */
.days-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 24px;
}

.day-card {
    background-color: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    border-radius: var(--border-radius);
    padding: 24px;
    border: 1px solid var(--border-color);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

.day-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px rgba(0,0,0,0.2);
    border-color: var(--primary);
}

.day-card.completed {
    border-color: var(--accent-cografya);
}

.day-card.completed::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background-color: var(--accent-cografya);
}

.day-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--border-color);
}

.day-title {
    font-size: 18px;
    font-weight: 700;
}

.day-progress {
    font-size: 14px;
    color: var(--text-muted);
    font-weight: 600;
}

.task-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.task-item {
    display: flex;
    align-items: flex-start;
    gap: 12px;
}

.task-checkbox {
    appearance: none;
    width: 22px;
    height: 22px;
    border: 2px solid var(--text-muted);
    border-radius: 6px;
    cursor: pointer;
    position: relative;
    transition: var(--transition);
    flex-shrink: 0;
    margin-top: 2px;
}

.task-checkbox:checked {
    background-color: var(--primary);
    border-color: var(--primary);
}

.task-checkbox:checked::after {
    content: '\f00c';
    font-family: 'Font Awesome 6 Free';
    font-weight: 900;
    color: white;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 12px;
}

.task-content {
    flex: 1;
}

.task-subject {
    font-size: 12px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 4px;
}

.task-subject.tarih { color: var(--accent-tarih); }
.task-subject.cografya { color: var(--accent-cografya); }
.task-subject.vatandaslik { color: var(--accent-vatandaslik); }
.task-subject.turkce { color: var(--accent-turkce); }
.task-subject.matematik { color: var(--accent-matematik); }

.task-title {
    font-size: 14px;
    line-height: 1.4;
    transition: var(--transition);
}

.task-checkbox:checked + .task-content .task-title {
    text-decoration: line-through;
    color: var(--text-muted);
}

.task-actions {
    display: flex;
    gap: 8px;
    margin-top: 8px;
}

.action-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-muted);
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 12px;
    cursor: pointer;
    transition: var(--transition);
}

.action-btn:hover {
    color: var(--text-main);
    border-color: var(--text-main);
}

.action-btn.cornell-btn:hover {
    color: var(--accent-vatandaslik);
    border-color: var(--accent-vatandaslik);
}

.action-btn.mistake-btn:hover {
    color: var(--accent-tarih);
    border-color: var(--accent-tarih);
}

/* Modals */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background-color: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(5px);
    z-index: 100;
    display: flex;
    justify-content: center;
    align-items: center;
}

.modal-content {
    background-color: var(--bg-panel);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    width: 90%;
    max-width: 800px;
    max-height: 90vh;
    display: flex;
    flex-direction: column;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    animation: modalSlideIn 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes modalSlideIn {
    from { opacity: 0; transform: scale(0.95) translateY(20px); }
    to { opacity: 1; transform: scale(1) translateY(0); }
}

.modal-header {
    padding: 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.close-modal {
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 20px;
    cursor: pointer;
    transition: var(--transition);
}

.close-modal:hover {
    color: var(--accent-tarih);
    transform: rotate(90deg);
}

/* Cornell Grid */
.cornell-grid {
    padding: 24px;
    display: grid;
    grid-template-columns: 250px 1fr;
    grid-template-rows: 1fr auto;
    gap: 20px;
    flex: 1;
    min-height: 500px;
}

.cornell-cues {
    grid-column: 1 / 2;
    grid-row: 1 / 2;
}

.cornell-notes {
    grid-column: 2 / 3;
    grid-row: 1 / 2;
}

.cornell-summary {
    grid-column: 1 / 3;
    grid-row: 2 / 3;
}

.cornell-grid h3 {
    font-size: 14px;
    color: var(--text-muted);
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.cornell-grid textarea {
    width: 100%;
    height: calc(100% - 25px);
    background-color: rgba(15, 23, 42, 0.5);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 16px;
    color: var(--text-main);
    font-family: inherit;
    resize: none;
    transition: var(--transition);
}

.cornell-grid textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 2px rgba(59, 130, 246, 0.2);
}

.cornell-summary textarea {
    height: 120px;
}

.modal-footer {
    padding: 20px 24px;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
}

/* Filters & Controls */
.controls-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
}

.filter-group {
    display: flex;
    gap: 10px;
}

.filter-btn {
    background-color: var(--bg-panel);
    border: 1px solid var(--border-color);
    color: var(--text-muted);
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.filter-btn.active, .filter-btn:hover {
    background-color: var(--primary);
    color: white;
    border-color: var(--primary);
}

/* Feature specific styling to be injected via JS */
.pomodoro-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    text-align: center;
}

.timer-display {
    font-size: 120px;
    font-family: 'Outfit', sans-serif;
    font-weight: 800;
    color: var(--primary);
    text-shadow: 0 0 40px var(--primary-glow);
    margin: 40px 0;
    line-height: 1;
}

.timer-controls {
    display: flex;
    gap: 20px;
}

.btn-large {
    padding: 16px 40px;
    font-size: 18px;
    border-radius: 30px;
}

/* Utility */
.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 60px 20px;
    text-align: center;
    color: var(--text-muted);
}

.empty-state i {
    font-size: 64px;
    margin-bottom: 20px;
    opacity: 0.5;
}

/* Gamification & Focus Styles */
body.zen-mode-active .sidebar {
    display: none !important;
}
body.zen-mode-active .topbar {
    display: none !important;
}
body.zen-mode-active .main-content {
    margin-left: 0;
    padding-top: 20px;
}
body.zen-mode-active .day-card {
    max-width: 800px;
    margin: 0 auto 30px auto;
    transform: scale(1.05);
    transition: 0.5s;
    box-shadow: 0 20px 40px rgba(0,0,0,0.5);
}

.lofi-btn:hover {
    filter: brightness(1.2);
}

.confetti-piece {
    position: fixed;
    width: 10px;
    height: 30px;
    background: #f00;
    top: -20px;
    z-index: 9999;
    animation: makeItRain 3s forwards;
}
@keyframes makeItRain {
    0% { transform: translateY(0) rotate(0deg); opacity: 1; }
    100% { transform: translateY(100vh) rotate(720deg); opacity: 0; }
}

/* Calendar Grid Styles */
.calendar-container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 20px;
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
}
.calendar-grid {
    display: grid;
    grid-template-columns: repeat(10, 1fr);
    gap: 12px;
    margin-top: 20px;
}
.cal-day {
    aspect-ratio: 1;
    border-radius: 8px;
    background: rgba(255,255,255,0.05);
    border: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: 0.3s;
    position: relative;
}
.cal-day:hover {
    transform: scale(1.1);
    z-index: 2;
    box-shadow: 0 0 15px rgba(255,255,255,0.1);
}
.cal-day.completed {
    background: var(--accent-cografya);
    color: #fff;
    border-color: var(--accent-cografya);
    box-shadow: 0 0 10px rgba(16, 185, 129, 0.4);
}
.cal-day.pending {
    background: var(--accent-turkce);
    color: #fff;
    border-color: var(--accent-turkce);
}
.cal-day.mock {
    border-radius: 50%;
    border: 2px dashed var(--accent-tarih);
}

/* Pomodoro Pet */
.pomodoro-pet {
    font-size: 64px;
    text-align: center;
    margin: 20px 0;
    filter: drop-shadow(0 0 10px rgba(255,255,255,0.2));
    transition: 0.5s;
}
.pomodoro-pet.sleeping {
    opacity: 0.5;
    animation: breathe 3s infinite ease-in-out;
}
@keyframes breathe {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
}