:root {
    --bg-color: #000000;
    --text-color: #f5f5f7;
    --card-bg: #1c1c1e;
    --primary-color: #ff453a;
    /* System Red (Dark Mode) */
    --short-break-color: #30d158;
    /* System Green (Dark Mode) */
    --long-break-color: #0a84ff;
    /* System Blue (Dark Mode) */
    --button-text: #ffffff;
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.6);
    --transition: 0.3s cubic-bezier(0.25, 0.1, 0.25, 1);
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: 'Inter', sans-serif;
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.container {
    width: 90%;
    max-width: 480px;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

h1 {
    font-size: 1.5rem;
    margin: 0;
}

.timer-card {
    background-color: var(--card-bg);
    border-radius: 20px;
    padding: 2rem;
    text-align: center;
    box-shadow: var(--shadow);
    transition: background-color var(--transition);
}

.modes {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.mode-btn {
    background: transparent;
    border: none;
    color: var(--text-color);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.9rem;
    opacity: 0.6;
    transition: all 0.2s;
}

.mode-btn.active {
    background-color: rgba(255, 255, 255, 0.1);
    font-weight: bold;
    opacity: 1;
}

.timer-display {
    font-size: 6rem;
    font-weight: 700;
    margin: 1rem 0;
    font-variant-numeric: tabular-nums;
    line-height: 1;
}

.controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

button {
    cursor: pointer;
    font-family: inherit;
}

.primary-btn {
    background-color: var(--primary-color);
    color: var(--button-text);
    border: none;
    padding: 1rem 2.5rem;
    font-size: 1.2rem;
    border-radius: 8px;
    text-transform: uppercase;
    font-weight: bold;
    letter-spacing: 1px;
    transition: transform 0.1s, background-color 0.2s;
    /* Box shadow for "pressable" feel */
    box-shadow: 0 4px 0 rgba(0, 0, 0, 0.15);
}

.primary-btn:active {
    transform: translateY(4px);
    box-shadow: none;
}

.primary-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.icon-btn {
    background: none;
    border: none;
    color: var(--text-color);
    padding: 0.5rem;
    border-radius: 50%;
    transition: background-color 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.icon-btn:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

.status-panel {
    text-align: center;
    font-size: 0.9rem;
    opacity: 0.8;
}

.settings-section {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.secondary-btn {
    background: none;
    border: 1px solid var(--text-color);
    color: var(--text-color);
    padding: 0.5rem 1rem;
    border-radius: 8px;
    opacity: 0.5;
    transition: opacity 0.2s;
}

.secondary-btn:hover {
    opacity: 1;
}

.settings-panel {
    background-color: var(--card-bg);
    padding: 1.5rem;
    border-radius: 12px;
    margin-top: 1rem;
    width: 100%;
    box-sizing: border-box;
    box-shadow: var(--shadow);
}

.settings-panel.hidden {
    display: none;
}

.setting-group {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.setting-toggle-group {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    padding-top: 0.5rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

input[type="number"] {
    width: 60px;
    padding: 0.3rem;
    border-radius: 4px;
    border: 1px solid #ccc;
    background: var(--bg-color);
    color: var(--text-color);
}

.settings-actions {
    margin-top: 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.primary-btn.small {
    padding: 0.5rem 1rem;
    font-size: 1rem;
}

.text-btn {
    background: none;
    border: none;
    color: var(--text-color);
    text-decoration: underline;
    font-size: 0.8rem;
    opacity: 0.6;
}

/* Dynamic Theme Colors based on Mode */
body[data-mode="shortBreak"] {
    --primary-color: var(--short-break-color);
}

body[data-mode="longBreak"] {
    --primary-color: var(--long-break-color);
}