:root {
    /* White Mode Variables */
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-muted: #6c757d;
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --secondary-color: #e9ecef;
    --secondary-hover: #dee2e6;
    --accent-color: #007bff;
    --danger-color: #dc3545;
    --shadow: 0 4px 12px rgba(0,0,0,0.08);
    --border-color: #e9ecef;
    --glow: none;
    --gradient: linear-gradient(135deg, #007bff, #00bfff);
}

body.dark-mode {
    /* Dark Mode Variables */
    --bg-color: #0d0d12;
    --card-bg: #1a1a24;
    --text-color: #f8f9fa;
    --text-muted: #adb5bd;
    --primary-color: #7b2cbf;
    --primary-hover: #9d4edd;
    --secondary-color: #2a2a35;
    --secondary-hover: #3a3a45;
    --accent-color: #e0aaff;
    --danger-color: #ff4d4d;
    --shadow: 0 8px 32px rgba(0,0,0,0.5);
    --border-color: #3a3a45;
    --glow: 0 0 15px var(--accent-color), 0 0 30px var(--primary-color);
    --gradient: linear-gradient(135deg, #7b2cbf, #ff006e, #ffbe0b);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.4s ease, color 0.4s ease;
    line-height: 1.6;
    min-height: 100vh;
}

/* Typography & Utils */
h1, h2, h3, h4 {
    margin-bottom: 0.5rem;
    font-weight: 600;
}
.mt-1 { margin-top: 1rem; }
.mt-2 { margin-top: 2rem; }
.mb-2 { margin-bottom: 2rem; }
.text-center { text-align: center; }
.hidden { display: none !important; }
.accent-text { color: var(--accent-color); }
body.dark-mode .accent-text { text-shadow: var(--glow); }

/* Header & Nav */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    background-color: var(--card-bg);
    box-shadow: var(--shadow);
    transition: background-color 0.4s ease, box-shadow 0.4s ease;
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: body.dark-mode ? var(--glow) : none;
}

body.dark-mode .logo {
    filter: drop-shadow(0 0 8px var(--primary-color));
}

nav {
    display: flex;
    gap: 1rem;
}

.nav-btn {
    background: none;
    border: none;
    font-size: 1rem;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    transition: all 0.3s ease;
}

.nav-btn:hover {
    background-color: var(--secondary-color);
    color: var(--text-color);
}

.nav-btn.active {
    color: var(--bg-color);
    background: var(--gradient);
    box-shadow: var(--glow);
    font-weight: bold;
}

.icon-btn {
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 50%;
    transition: background-color 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.icon-btn:hover {
    background-color: var(--secondary-color);
}

/* Main Content */
main {
    max-width: 800px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.page-section {
    display: none;
    animation: fadeIn 0.4s ease;
}

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

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

/* Cards */
.card {
    background-color: var(--card-bg);
    border-radius: 16px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    transition: all 0.4s ease;
}

body.dark-mode .card {
    border: 1px solid rgba(255,255,255,0.1);
}

body.dark-mode .card:hover {
    box-shadow: var(--glow);
    border-color: var(--accent-color);
}

/* Dashboard Cards */
.next-exercise-card {
    text-align: center;
}

.next-exercise-preview {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
}

.next-exercise-preview img {
    width: 80px;
    height: 80px;
    border-radius: 8px;
    background-color: white;
    object-fit: contain;
    box-shadow: var(--shadow);
}

body.dark-mode .next-exercise-preview img {
    box-shadow: var(--glow);
}

.preview-info {
    text-align: left;
}

.streak-card {
    text-align: center;
}

.main-streak {
    margin-bottom: 2rem;
    padding: 3rem 1.5rem;
}

.streak-circle {
    width: 150px;
    height: 150px;
    border-radius: 50%;
    background: var(--card-bg);
    border: 8px solid var(--primary-color);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    margin: 1.5rem auto;
    box-shadow: var(--glow);
    transition: all 0.4s ease;
}

.streak-value {
    font-size: 3rem;
    font-weight: bold;
    color: var(--text-color);
    line-height: 1;
}

.streak-label {
    font-size: 1rem;
    color: var(--text-muted);
}

.mini-streaks-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 1rem;
}

.mini-streak h3 {
    font-size: 1rem;
    color: var(--text-muted);
}

.streak-value-small {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--accent-color);
    text-shadow: body.dark-mode ? var(--glow) : none;
}

/* Progress Bar */
.progress-bar-container {
    height: 12px;
    background-color: var(--secondary-color);
    border-radius: 6px;
    overflow: hidden;
    margin-top: 1rem;
}

.progress-bar {
    height: 100%;
    background: var(--gradient);
    box-shadow: var(--glow);
    transition: width 0.5s ease;
}

/* Exercise Section */
.exercise-card {
    text-align: center;
    max-width: 500px;
    margin: 0 auto;
}

.exercise-image-container img {
    width: 100%;
    max-width: 250px;
    border-radius: 12px;
    margin: 1.5rem 0;
    box-shadow: var(--shadow);
    background-color: white; /* Da Bilder White bg haben */
    padding: 1rem;
}

body.dark-mode .exercise-image-container img {
    box-shadow: var(--glow);
}

/* Timer */
.timer-display {
    position: relative;
    width: 160px;
    height: 160px;
    margin: 2rem auto;
}

.timer-ring {
    transform: rotate(-90deg);
}

.timer-ring-bg {
    fill: none;
    stroke: var(--secondary-color);
    stroke-width: 8;
}

.timer-ring-progress {
    fill: none;
    stroke: var(--primary-color);
    stroke-width: 8;
    stroke-linecap: round;
    stroke-dasharray: 439.8; /* 2 * pi * 70 */
    stroke-dashoffset: 0;
    transition: stroke-dashoffset 1s linear;
}

body.dark-mode .timer-ring-progress {
    filter: drop-shadow(0 0 10px var(--accent-color));
}

.timer-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 2rem;
    font-weight: bold;
    color: var(--text-color);
}

.duration-selectors {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

.duration-btn {
    padding: 0.5rem 1.5rem;
    border: 2px solid var(--border-color);
    background: transparent;
    color: var(--text-color);
    border-radius: 20px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.3s ease;
}

.duration-btn.active {
    border-color: var(--primary-color);
    color: var(--primary-color);
    background-color: var(--primary-color);
    color: #fff;
    box-shadow: var(--glow);
}

body.dark-mode .duration-btn.active {
    color: #fff;
    background: var(--gradient);
    border-color: transparent;
}

/* Buttons */
.primary-btn, .secondary-btn {
    padding: 0.8rem 2rem;
    border: none;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
}

.primary-btn {
    background: var(--gradient);
    color: white;
    box-shadow: var(--shadow);
}

body.dark-mode .primary-btn {
    box-shadow: var(--glow);
}

.primary-btn:hover {
    opacity: 0.9;
    transform: translateY(-2px);
}

.secondary-btn {
    background-color: var(--secondary-color);
    color: var(--text-color);
}

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

.secondary-btn.danger {
    color: white;
    background-color: var(--danger-color);
}

/* Reference List */
.category {
    margin-bottom: 2rem;
}

.exercise-list {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
    margin-top: 1rem;
}

.reference-card {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    padding: 1rem;
}

.reference-card img, .placeholder-img {
    width: 80px;
    height: 80px;
    border-radius: 8px;
    object-fit: contain;
    background-color: white;
}

.placeholder-img {
    background-color: var(--secondary-color);
    display: flex;
    align-items: center;
    justify-content: center;
}

.ref-info h4 {
    margin-bottom: 0.25rem;
    color: var(--accent-color);
}

/* Settings */
.setting-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

select, .text-input {
    padding: 0.8rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-color);
    color: var(--text-color);
    font-size: 1rem;
}

select {
    cursor: pointer;
}

select:focus, .text-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.status-text {
    font-size: 0.9rem;
    color: var(--text-muted);
}